Дисертації з теми "Foot muscle"

One major way that running style varies between individuals is how their foot strikes the ground (forefoot strike or rearfoot strike). Running generates a torque about the ankle that depends on the individual’s foot strike pattern, length of their plantar flexor moment arm, and force generated from the plantar flexor muscles. The foot strike pattern during running, gastrocnemii muscle thickness, and heel length (used as an approximation for plantar flexor moment arm) were determined in 41 runners. Forefoot and rearfoot strike runners had the same thickness of the gastrocnemii muscles. However, in comparison with sedentary walkers, the runners had thicker calf muscles. These results imply a “peak” muscle thickness seems to be attained by running. Runners with longer heels were more likely to use a forefoot strike running style, possibly due to a mechanical advantage in the generation of torque.

Background: Maximal muscle strength and body proportions are some of the key attributes to be a fast swimmer. Even though dolphin kick (DK) has become essential to be a fast swimmer little is known of its associations to muscle strength and body proportions. Moreover, the effect of feet size has been stated to be a primary contributor to dolphin kick thrust production, but scientific evidence is still scarce. Aim: The aim of this study was to examine the correlation between lower extremity muscle strength, abdominal strength and feet length with dolphin kick performance over 15 meters in active competitive swimmers 15-20 years old Method: Twelve Test subjects (six male and six female) participated. Test subjects performed four 15 meters dolphin kick trials. Lower extremity muscle strength was tested with a three repetition maximum strength test and abdominal strength with brutal bench test. The muscles tested were rectus femoris, biceps femoris and rectus abdominis. Feet length was measured with a measuring tape. The correlations between lower extremity strength, abdominal strength and feet length with dolphin kick performance were calculated with spearman’s correlation. Results: Twelve test subjects between ages 15-20 years old participated. Spearman correlation test showed that lower extremity strength (rectus femoris: rs=-0.57 and biceps femoris: rs=-0.66) had a large association with dolphin kick performance. Abdominal strength (rs=-0.46) and feet length (rs=-0.35) had a moderate association with dolphin kick performance. Conclusion: The present study conclude that lower extremity strength is important for DK performance over 15 meters and that abdominal strength and feet length also is important but is less associated to it. The finding from this study can be used for making training programs for improving DK performance and for scouting swimmers with beneficial traits for specific swimming technique.

Thesis (M.A.)--University of North Carolina at Chapel Hill, 2006.
Title from electronic title page (viewed Oct. 10, 2007). "... in partial fulfillment of the requirements for the degree of Master of Arts in the Department of Exercise and Sport Science (Athletic Training)." Discipline: Exercise and Sports Science; Department/School: Exercise and Sport Science.

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Background: Botulinum toxin type A (BTX-A), one of the most potent biological toxins, acts by blocking neuromuscular transmission via inhibiting acetylcholine release and is a well-known treatment for poststroke spasticity, despite some variations among dose protocols. Spasticity is one of the factors that affect the functional rehabilitation process in stroke. Spasticity arises from the loss of myotatic reflex inhibition, resulting from upper motor neuron lesion. Equinus foot is common in lower limb spasticity after stroke worsening gait pattern and functional independence. The objective of this study is to evaluate the effects of BTX-A different doses on spastic foot in stroke patients in rehabilitation programme and on gait velocity and functional independence of these patients. Methods: This study was a randomized, prospective and double blind trial. Patients were recruited if they had diagnosis of stroke (ischemic or hemorrhagic) with a poststroke period of at least six months and hemiparesis with spastic equinus foot (Ashworth score 3 or 4 in a range from 0 to 5). Twenty-one hemiparetic stroke patients enrolled in a rehabilitation programme were divided into two groups. The first group (n=11) received BTX-A 300UI in spastic foot and the second group (n=10) received BTX-A 100UI. All patients were assessed at baseline and 2, 4, 8 and 12 weeks after injection for passive range of motion for ankle joint, Modified Ashworth Score, time walking 10 meters, clonus score and motor score of Functional Independence Measure (mFIM). Results: Higher dose group had significant improvement in range of motion on week 12 (p=0,021) and in Ashworth score on weeks 8 (p=0,012) and 12 (p < 0,0001) compared with lower dose group. There was slight improvement in clonus score in higher dose group on week 12 without statistical significance. Both groups had improvement in time walking 10 meters and mFIM without significant difference between them in the analyzed sample. There was no significant adverse effect. Conclusions: BTX-A is an important tool in poststroke rehabilitation for spasticity parameters improvement, but there was no significant difference between high and low doses of BTX-A for gait velocity neither for functional independence in the analyzed sample. Future studies with larger number of patients and evaluation of response to BTX-A reapplications are necessary to confirm these findings.
IntroduÃÃo: A toxina botulÃnica tipo A (TbA), uma das mais potentes toxinas biolÃgicas, age atravÃs do bloqueio da transmissÃo neuromuscular via inibiÃÃo da liberaÃÃo de acetilcolina e à um tratamento bem-estabelecido para espasticidade pÃs-AVE, apesar de variaÃÃes entre os protocolos de doses em diferentes centros. Espasticidade à um dos fatores que interferem no processo de reabilitaÃÃo funcional apÃs acidente vascular encefÃlico (AVE). Ela surge por causa da perda da inibiÃÃo do reflexo miotÃtico, resultante de lesÃo do neurÃnio motor superior. O pà equino à comum na espasticidade de membro inferior depois do AVE e sua instalaÃÃo piora o padrÃo de marcha e a independÃncia funcional. O objetivo desse estudo à avaliar os efeitos da TbA em diferentes doses sobre o pà espÃstico de pacientes com sequela de AVE inseridos em programa de reabilitaÃÃo e sobre a velocidade de marcha e independÃncia funcional desses pacientes. Metodologia: Este estudo foi realizado atravÃs de ensaio randomizado, prospectivo e duplo cego. Foram recrutados pacientes com diagnÃstico de AVE (isquÃmico ou hemorrÃgico) com perÃodo pÃs-AVE de pelo menos seis meses e hemiparesia com pà equino espÃstico (escore Ashworth 3 ou 4 em uma escala de 0 a 5). Vinte e um pacientes hemiparÃticos pÃs-AVE inseridos em programa de reabilitaÃÃo foram divididos em dois grupos. O primeiro grupo (n=11) recebeu aplicaÃÃo de 300UI de TbA no pà espÃstico e o segundo grupo (n=10) recebeu 100UI de TbA. Todos os pacientes foram avaliados no tempo zero e 2, 4, 8 e 12 semanas apÃs a injeÃÃo quanto aos seguintes parÃmetros: amplitude de movimento passivo da articulaÃÃo do tornozelo, escala de Ashworth modificada, tempo para andar 10 metros, escore clÃnus de aquileu e escore motor da Medida de IndependÃncia Funcional (MIFm). Resultados: O grupo 300UI TbA teve melhora significativa da amplitude de movimento na 12 semana (p=0,021) e da escala de Ashworth nas 8 (p=0,012) e 12 (p < 0,0001) semanas em comparaÃÃo ao grupo 100UI TbA. Houve tendÃncia à melhora do escore clÃnus na 12 semana no grupo 300UI TbA. Ambos os grupos apresentaram melhora durante o estudo no tempo para andar 10 metros e da MIFm sem diferenÃa significativa entre eles. NÃo foram observados efeitos adversos significativos no decorrer do estudo. ConclusÃes: TbA à uma importante ferramenta na reabilitaÃÃo pÃs-AVE para melhora dos parÃmetros de espasticidade, mas nÃo houve diferenÃa significativa entre dose alta e baixa de TbA para parÃmetros funcionais (velocidade de marcha e independÃncia funcional), na amostra analisada. Estudos futuros com um nÃmero maior de pacientes e avaliaÃÃo de resposta a reaplicaÃÃes de TbA sÃo necessÃrios para confirmaÃÃo desses achados.

Idiopathic clubfoot causes severe deformity of the foot and lower leg. Due to the complex anatomy and small size of the foot, the condition is difficult to define and describe. This study focused on 3D modeling of different foot positions associated with clubfoot relapse, and investigation of muscle parameters. The 3D modeling was performed in the AnyBody Modeling System to retrieve information about muscle length. Musculoskeletal modeling could provide further understanding of the condition and contribute to assessment and treatment evaluation. Five children that received clubfoot treatment as infants, and five typically developing children, serving as a control group, participated in the study. Despite treatment with the Ponseti method, Achilles tenotomy and use of an abduction orthosis, all participants of the clubfoot group showed signs of relapse. In total, seven affected legs were studied. Data from gait analyses of all participants were compiled and interpreted in the AnyBody Modeling System. The Plug-in-Gait Model for lower extremities and the Oxford Foot Model were used as marker protocol for the study. Studied lower leg muscles were Gastrocnemius Lateralis, Gastrocnemius Medialis, Soleus Lateralis and Soleus Medialis. Muscle length, defined as length of contractile element, for each leg and participant were evaluated using the AnyBody model template LowerExtremity. Compared to the control group, the models of the clubfoot group presented shorter mean muscle lengths of all investigated muscles.
Idiopatisk klumpfot orsakar allvarlig deformation av fot och underben. På grund av fotens anatomi och ringa storlek kan tillståndet vara svårt att beskriva och definiera. Denna studie innefattade 3Dmodellering av olika fotpositioner orakade av recidivklumpfot, för att undersöka muskelegenskaper. AnyBody Modeling System användes för att generera 3D-modeller och ta fram information om muskellängd. Muskuloskeletal modellering skulle kunna öka förståelsen för sjukdomen och bidra till förbättringar av initial bedömning och utvärdering av behandling. Fem barn som behandlades för klumpfot efter födseln deltog i studien. Även fem typiskt utvecklade barn medverkade och fungerade som en kontrollgrupp. Trots behandling med Ponseti-metoden, hälseneförlängning och användning av abduktionsortos, uppvisade samtliga barn i klumpfotsgruppen tecken på återfall. Totalt studerades sju ben med recidivklumpfot. Data från gånganalyser av deltagarna sammanställdes och analyserades i AnyBody Modeling System. Plug-in-Gait Model för nedre extremiteter och Oxford Foot Model användes som markörprotokoll. Under studien analyserades underbensmusklerna Gastrocnemius Lateralis, Gastrocnemius Medialis, Soleus Lateralis och Soleus Medialis. Muskellängd (längd av kontraktilelement) för varje patient och ben beräknades med hjälp av modellmallen LowerExtremity i AnyBody Modeling System. Jämfört med kontrollgruppen visade klumpfotsgruppen kortare medelmuskellängder för samtliga av de analyserade musklerna.

Context: There has been recent speculation that the intrinsic muscles of the foot may play a larger role in lower extremity control and injury than previously believed. Multiple studies have shown that certain intrinsic muscles increase in size and strength after transitioning to minimalist shoe running, theoretically decreasing injury risk. There are currently no studies that examine the effect that training barefoot has in other athletic populations. Objective: Our purpose was to compare the intrinsic and extrinsic foot muscle size and strength in gymnasts (who predominantly train barefoot) and cheerleaders (who predominantly train shod). Another purpose was to measure time to stability for both groups shod and unshod. Design: Observational study. Setting: Human Performance Laboratory. Participants: 16 collegiate gymnasts (height = 159.3 ± 4.9cm, weight = 56.7 ± 4.3kg) and 16 collegiate cheerleaders (height = 161.9 ± 5.4cm, weight = 58.7 ± 7.1kg) volunteered for this study. Main Outcome Measure(s): The muscle size of 6 intrinsic and extrinsic muscles of the foot were measured using ultrasound, toe flexor strength, as assessed using a custom-made dynamometer, and time to stability following a drop landing, as assessed using ground reaction force data collected with force plates. Results: There were no significant group differences in great toe flexor strength (p = 0.274), lateral toe flexor strength (p = 0.824), or any of the time to stability conditions (p = 0.086 – 0.90). Only one muscle, fibularis longus, was significantly bigger in gymnasts than cheerleaders (p = 0.017) Conclusions: Our findings suggest that the barefoot training of gymnasts may not have as large of an impact on the foot musculature and strength as running barefoot or in minimalist shoes has on these factors.

The human foot contributes significantly to the function of the whole lower extremity during standing and locomotion. Nevertheless, the foot and ankle often suffer injuries and are affected by many musculoskeletal and neurological pathologies. The overall aim of this thesis was to evaluate gait parameters and muscle function change due to foot and ankle injury, malalignment and co-contraction. Using 3D gait analysis, analytical analyses and computational simulations, biomechanical consequences of gait impairment at the ankle and foot were explored in ablebodied persons and in patient groups with disorders affecting walking. We have characterized gait patterns of subjects with ankle fractures with a modified multi-segment foot model. The inter-segmental foot kinematics were determined during gait in 18 subjects one year after surgically-treated ankle fractures. Gait data were compared to an age- and gender-matched control group and the correlations between functional ankle score and gait parameters were determined. It was observed that even with fairly good clinical results, restricted range of motion and malalignment at and around the injured area were found in the injured limb. Moment-angle relationship (dynamic joint stiffness) - the relationship between changes in joint moment and changes in joint angle - is useful for demonstrating interaction of kinematics and kinetics during gait. Ankle dynamic joint stiffness during the stance phase of gait was analyzed and decomposed into three components in thirty able-bodied children, eight children with juvenile idiopathic arthritis and eight children with idiopathic toe-walking. Compared to controls, the component associated with changes of ground reaction moment was the source of highest deviation in both pathological groups. Specifically, ankle dynamic joint stiffness differences can be further identified via two subcomponents of this component which are based on magnitudes and rates of change of the ground reaction force and of its moment arm. And differences between the two patient groups and controls were most evident and interpretable here. Computational simulations using 3D musculoskeltal models can be powerful in investigating movement mechanisms, which are not otherwise possible or ethical to measure experimentally. We have quantified the effect of subtalar malalignment on the potential dynamic function of the main ankle dorsiflexors and plantarflexors: the gastrocnemius, soleus and tibialis anterior. Induced acceleration analysis was used to compute muscle-induced joint angular and body center of mass accelerations. A three-dimensional subject-specific linkage model was configured by gait data and driven by 1 Newton of individual muscle force. The excessive subtalar inversion or eversion was modified by offsetting up to ±20˚ from the normal subtalar angle while other configurations remain unaltered. We confirmed that in normal gait, muscles generally acted as their anatomical definitions, and that muscles can create motion in many joints, even those not spanned by the muscles. Excessive subtalar eversion was found to enlarge the plantarflexors’ and tibialis anterior’s function. In order to ascertain the reliability of muscle function computed from simulations, we have also performed a parametric study on eight healthy adults to evaluate how sensitive the muscle-induced joints’ accelerations are to the parameters of rigid foot-ground contact model. We quantified accelerations induced by the gastrocnemius, soleus and tibialis anterior on the lower limb joints. Two types of models, a ‘fixed joint’ model with three fixed joints under the foot and a ‘moving joint’ model with one joint located along the moving center of pressure were evaluated. The influences of different foot-ground contact joint constraints and locations of center of pressure were also investigated. Our findings indicate that both joint locations and prescribed degrees-of-freedom of models affect the predicted potential muscle function, wherein the joint locations are most influential. The pronounced influences can be observed in the non-sagittal plane. Excessive muscle co-contraction is a cause of inefficient or abnormal movement in some neuromuscular pathologies. We have identified the necessary compensation strategies to overcome excessive antagonistic muscle cocontraction at the ankle joint and retain a normal walking pattern. Muscle-actuated simulation of normal walking and induced acceleration analysis were performed to quantify compensatory mechanisms of the primary ankle and knee muscles in the presence of normal, medium and high levels of co-contraction of two antagonistic pairs (gastrocnemiustibialis anterior and soleus-tibialis anterior). The study showed that if the co-contraction level increases, the nearby synergistic muscles can contribute most to compensation in the gastrocnemius-tibialis anterior pair. In contrast, with the soleus-tibialis anterior co-contraction, the sartorius and hamstrings can provide important compensatory roles in knee accelerations. This dissertation documented a broad range of gait mechanisms and muscle functions in the foot and ankle area employing both experiments and computational simulations. The strategies and mechanisms in which altered gait and muscles activation are used to compensate for impairment can be regarded as references for evaluation of future patients and for dynamic muscle functions during gait.
QC 20120514

Abstract Introduction: The prevalence of anterior cruciate ligament tear is around 7000 every year within the swedish population and 95% of reconstructive surgery was with a hamstring tendon graft. Six months post surgery a 13% decrease in knee flexion strength compared to non injured side. The need for a study that determine the role of gastrocnemius and foot position in knee flexion is lacking in the litterature and could benefit Physiotheraphy ACL rehabilitation. Purpose: of his study was to investigate M gastrocnemius medialis (MGM) activation in the ipsilateral knee after removal of hamstring tendon for ACLR, and se if ankle position alter knee flexion outcomes. Method: 3 women, mean age 24 years who underwent ACL reconstruction with hamstring graft on one leg was tested. The time since injury was 3, 6 and 7 years respectively with an mean ,5 years wait until surgery. Isokinetic knee flexion and extension testing was done in the Biodex system 3 pro. EMG electrodes measured medial gastrocnemius activation with and without ankle in dorsiflexion. Results: Knee flexion peak strength was higher by a mean of 3 Nm (3,5%) with dorsiflexed foot. Mean (MGM) activation remained the same with or without dorsiflexion. Overall knee flexion strength was higher by a mean of 5 Nm compared to the injured side. Conclusion: Knee flexion in the biodex with foot in dorsiflexion could allow for isometric plantarflexion and increas power output. Certain changes in inclusion criteria and methodology as well more studies is needed to come to a given conclusion.
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Tyrimo pagrindimas: sportininkų judėjimo gebėjimai vyksta dalyvaujant paskutiniai grandžiai pėdos lenkiamiesiems ir tiesiamiesiems raumenims (Нечаев, 2011). Didelio meistriškumo graikų-romėnų imtynininkų raumenų kraujotakos mobilizacijos ir atsigavimo ypatybės yra artimesnės ištvermės sporto šakų atstovams nei sprinto grupės sportininkų ypatybėms. (Ežerskis, 2009). Tikslas- išanalizuoti skirtingos adaptacijos fiziniams krūviams vyrų ir merginų pėdų lenkiamųjų raumenų funkcinius ypatumus. Hipotezė: pėdos lenkiamųjų raumenų ištvermė priklauso nuo maksimalios valingos jėgos dydžių, kuo didesnė jėga, tuo mažesnė ištvermė. Metodai: dinamometrija, literatūros šaltinių studija, statistinė analizė. Aptarimas ir Išvados: dvikovos sportininkių, ištvermės ir greitumo jėgos atstovų tarpusavyje kairės ir dešinės kojos jėga nesiskyrė yra proporcingų dydžių. Ištvermės sportininkų vyrų pėdos lenkiamųjų raumenų kojų jėga buvo ženkliai didesnė už dvikovos, sporto šakų, tačiau mažesnė nei greitumo jėgos atstovų. Dvikovos sporto šakų sportininkių ir ištvermės atstovų bei greitumo jėgos sportininkų MRI rodikliai skyrėsi neženkliai, tačiau jėga buvo mažesnė Nuo jėgos dydžio priklauso ištvermės trukmė. Esant didesnei jėgai ištvermės trukmė mažėja. Pagal santykio MVJ/MRI reikšmes visos priklauso stajerio tipui. Tyrimo uždaviniai: 1. Nustatyti dvikovos sporto šakų moterų ir vyrų, pėdos lenkiamųjų raumenų maksimalios valingos jėgos dydžius. 2. Nustatyti dvikovos sporto šakų moterų ir vyrų, pėdos... [toliau žr. visą tekstą]
Introduction: Atlete's movement depends on the activity of the foot flexor muscle strength and endurance. High craftsmanship Greco- Roman wrestlers muscle blood mobilization and recovery features are closer to endurance sports disciplines than sprint atlete properties. Aim: Analysis the different physical exertion adaptation of men and a girl's foot muscle flexion functional features. Hypothesis: foot flexor muscle endurance duel sport athletes are the same length as the representatives of the endurance strength but size was lager. Methods: dynamometry, literature study, a statistical analysis. Discussion and Conclusion: The duel athletes, endurance and speed power representatives each other left and right leg power is proportional not different sizes. Endurance representatives of men's foot flexor muscles leg strength was significantly higher than the duel sports, but less than the speed force representatives. Duel sport athletes and endurance representatives maximal muscle endurance characteristics differed slightly, but the force was smaller size of the force depends on endurance time. At higher power of endurance time decreases. According to the ratio of maximal voluntary contruction / maximal muscle endurance values all belong stajer type. Exploratory tasks : 1)set duel sports for men and women, foot flexion maximum voluntary muscle force figures. 2)Set duel sports for men and women, foot flexor muscle endurance for maximum muscle size. 3)Identify and analyze the duel... [to full text]

Background:People who have survived a stroke often have post-stroke complications. One common complication is muscle weakness in the lower extremities. To treat this, patients can use an ankle-foot orthosis (AFO). The purpose of this study was to investigate muscle morphology in the quadriceps when walking with an AFO. Method:This feasibility cross over study was made on 7 healthy adults. To measure the morphology, an SMG device was used. The device measured muscle area change, EMG -and MMG activation, knee angle and plantar forces. Statistical analyzes was made for all measured data except knee angle.  Result:The area of the quadriceps was significantly smaller when walking with the AFO in mid-swing phase than without (p=0,035). A significant reduction in force could also be found under the MTP1 (p=0,016) and under the calcaneus (p=0,042) in toe off (60%). The result did not show any significant differences in initial contact (p=0,617), mid stance (p=0,287), toe off (p=0,527) or terminal swing (p=0,712) for muscle area change of quadriceps, or plantar force at MTP5 in toe off (p=0,704). Conclusion:The results suggest that the subjects needed to work more with the quadriceps muscles when walking with the AFO. More studies are needed to reach clinical relevance.
Bakgrund:Personer som har genomgått en stroke lider ofta av diverse komplikationer. En vanlig komplikation är muskelsvaghet i den nedre extremiteten. Ett vanligt hjälpmedel för personer med dessa problem är en ankel-fot-ortos (AFO). Denna studies syfte var att undersöka muskelmorfologi (areaförändringar) i quadriceps muskeln när man går med en AFO jämfört med att gå utan.  Metod:Denna förstudie är en korsstudie som utfördes på 7 friska unga vuxna. Ett SMG-system användes på quadriceps för att mäta muskelarean. Enheten mätte muskelarea förändringar, EMG –och MMG aktivering, knävinkel samt plantara krafter. Statistiska analyser genomfördes på all insamlade data förutom knävinkeln.  Resultat:Arean för quadriceps var signifikant mindre när deltagarna gick med AFO i mid swing jämfört med utan (p=0,035). En signifikant skillnad visade sig i den plantara kraften under MTP1 (p=0,016) och under hälen (p=0,042) i toe off (60%).  Resultatet visade inga signifikanta skillnader i initial contact (p=0,617), mid stance (p=0,287), toe off (p=0,527) eller i terminal swing (p=0,712) för quadriceps, eller plantara krafter på MTP5 under toe off (p=0,704). Slutsats:Resultaten pekar på att deltagarna behöver använda sin quadriceps mer i mid swing när de går med en AFO. Fler studier på området behöver göras för att uppnå klinisk relevans.

Ankle-foot orthoses are commonly prescribed amongst subjects with diplegic cerebral palsy as a conservative orthotic intervention. Multi-articular and bi-articular muscles are more severely involved in subjects with diplegic cerebral palsy. Appropriate clinical assessment including assessment of these muscles enables optimum ankle-foot orthosis footwear combination (AFO-FC) prescription and any required adjunct therapy. The overarching aim of this thesis was to investigate the effect of optimisation of the temporal midstance shank kinematics with the use of an AFO- FC on several variables including shank kinematics, thigh kinematics, vertical component of ground reaction force (FZ2) and ground reaction force (GRF) alignment in relation to hip and knee joint in temporal midstance to late stance. The understanding of the implication of, and the tools used to conduct assessment procedures and measurement processes were tested in the assessment of bi-articular muscles (specifically rectus femoris), to ascertain if results were predictive of presenting gait deviations and hence provide information to optimise treatment. The results of initial study suggested that a positive influence on the shank kinematics, thigh kinematics, FZ2 and GRF alignment in relation to hip and knee joint in temporal midstance to late stance was observed with the use of an AFO-FC. The results of a further study illustrated that a dominance relationship of the catch angle/length of rectus femoris (RF) measured using the Duncan-Ely with the knee or the hip joints varies at different gait points/periods. Additionally, the effect of dynamic shortness of4the RF differed on gait from the effect of true shortness. The results of series of studies testing the feasibility of using a 2-dimensional analysis system (PnO Clinical Movement Data) for hip, knee and ankle sagittal plane passive joint range of motion measurement during physical assessment confirmed the reliability and accuracy of this system.

La pronation et les pieds plats ont longtemps été considérés conjointement, notamment dans leur relation avec la blessure. Or, cette relation, au regard des résultats divergents de la littérature, a été remise en question. Récemment, la dissociation entre la typologie et la fonctionnalité du pied a permis de mettre en évidence une possible association entre la pronation et la lombalgie. L’étude de la locomotion de sujets pronateurs identifiés par des tests fonctionnels pourrait exposer les facteurs de risques biomécaniques associés à la lombalgie. L’objectif général était d’identifier et d’étudier l’impact cinématique et baropodométrique de la pronation à la marche. Puis d’évaluer l’effet de traitements préventifs visant à limiter la biomécanique à risque dans un but de prévention primaire. Trois études ont été menées. Une étude de concordance entre différents tests d’identification de la pronation a été réalisée, dans des conditions différentes, afin de sélectionner un test approprié à l’étude de la marche. La cinématique et la baropodométrie de la marche de 159 sapeurs-pompiers professionnels, pronateurs vs non-pronateurs, ont été comparées. Deux protocoles d’un mois visant à réduire la pronation (renforcement musculaire du pied ou port de semelles) ont été proposés chez les sujets pronateurs. La concordance des différents tests de fonctionnalité a été jugée faible. Une combinaison de tests fonctionnels a été utilisée pour affiner le diagnostic de pronation. Les sujets pronateurs ont exposé des différences baropodométriques et cinématiques de l’avant et de l’arrière-pied, du genou et du bassin à la marche. Cette cinématique pourrait constituer un facteur de risque de lombalgie. La pronation a été réduite par les deux protocoles préventifs et accompagnée de modifications cinématiques du pied et de la hanche. Bien que nos protocoles préventifs ne témoignent pas d’une incidence sur le bassin, ils exposent une modification cinématique du membre inférieur, qui pourrait modifier la biomécanique du bassin et constituer un moyen de prévention des lombalgies
Pronation and flat feet have, for a long time, been associated, particularly in their relationship to injury. However, this relationship has been questioned in view of the divergent results in writings. Recently, the dissociation between foot-type and foot-function has highlighted a possible link between pronation and low back pain. The study of pronator subjects' way of moving, identified by foot function tests, could highlight the biomechanical risk factors associated with low back pain. The general objective was to identify and study the kinematic and plantar pressure impact of pronation while walking. Then to evaluate the effect of preventive treatments aimed aimed to limit the biomechanics at risk while keeping primary prevention in mind. Three studies were conducted. A concordance study between different pronation identification tests, under different conditions, was carried out in order to select an appropriate test for the study of gait. Gait kinematic and baropodometric analyses of 159 pronator vs non-pronator professional firefighters were then compared. Then, the effects of two one-month protocols aimed at reducing pronation (foot muscle strengthening or wearing insoles) were suggested to pronator subjects. Agreement between the different tests of foot-function identification was found to be low. A combination of functional tests was used to refine the identification of pronation. Pronator subjects showed plantar pressure and kinematic differences in the forefoot, hindfoot, knee and pelvis. These kinematic effects may reflect a risk factor for low back pain. Pronation was reduced by both preventive protocols wich were accompanied by kinematic changes in the foot and hip. Although our preventive protocols do not show an impact on the pelvis, they do show a kinematic change in the lower limb that could modify the biomechanics of the pelvis and provide a mean of preventing low back pain

In children, joint hypermobility (typified by structural instability of joints) manifests clinically as neuro-muscular and musculo-skeletal conditions and conditions associated with development and organization of control of posture and gait (Finkelstein, 1916; Jahss, 1919; Sobel, 1926; Larsson, Mudholkar, Baum and Srivastava, 1995; Murray and Woo, 2001; Hakim and Grahame, 2003; Adib, Davies, Grahame, Woo and Murray, 2005:). The process of control of the relative proportions of joint mobility and stability, whilst maintaining equilibrium in standing posture and gait, is dependent upon the complex interrelationship between skeletal, muscular and neurological function (Massion, 1998; Gurfinkel, Ivanenko, Levik and Babakova, 1995; Shumway-Cook and Woollacott, 1995). The efficiency of this relies upon the integrity of neuro-muscular and musculo-skeletal components (ligaments, muscles, nerves), and the Central Nervous System’s capacity to interpret, process and integrate sensory information from visual, vestibular and proprioceptive sources (Crotts, Thompson, Nahom, Ryan and Newton, 1996; Riemann, Guskiewicz and Shields, 1999; Schmitz and Arnold, 1998) and development and incorporation of this into a representational scheme (postural reference frame) of body orientation with respect to internal and external environments (Gurfinkel et al., 1995; Roll and Roll, 1988). Sensory information from the base of support (feet) makes significant contribution to the development of reference frameworks (Kavounoudias, Roll and Roll, 1998). Problems with the structure and/ or function of any one, or combination of these components or systems, may result in partial loss of equilibrium and, therefore ineffectiveness or significant reduction in the capacity to interact with the environment, which may result in disability and/ or injury (Crotts et al., 1996; Rozzi, Lephart, Sterner and Kuligowski, 1999b). Whilst literature focusing upon clinical associations between joint hypermobility and conditions requiring therapeutic intervention has been abundant (Crego and Ford, 1952; Powell and Cantab, 1983; Dockery, in Jay, 1999; Grahame, 1971; Childs, 1986; Barton, Bird, Lindsay, Newton and Wright, 1995a; Rozzi, et al., 1999b; Kerr, Macmillan, Uttley and Luqmani, 2000; Grahame, 2001), there has been a deficit in controlled studies in which the neuro-muscular and musculo-skeletal characteristics of children with joint hypermobility have been quantified and considered within the context of organization of postural control in standing balance and gait. This was the aim of this project, undertaken as three studies. The major study (Study One) compared the fundamental neuro-muscular and musculo-skeletal characteristics of 15 children with joint hypermobility, and 15 age (8 and 9 years), gender, height and weight matched non-hypermobile controls. Significant differences were identified between previously undiagnosed hypermobile (n=15) and non-hypermobile children (n=15) in passive joint ranges of motion of the lower limbs and lumbar spine, muscle tone of the lower leg and foot, barefoot CoP displacement and in parameters of barefoot gait. Clinically relevant differences were also noted in barefoot single leg balance time. There were no differences between groups in isometric muscle strength in ankle dorsiflexion, knee flexion or extension. The second comparative study investigated foot morphology in non-weight bearing and weight bearing load conditions of the same children with and without joint hypermobility using three dimensional images (plaster casts) of their feet. The preliminary phase of this study evaluated the casting technique against direct measures of foot length, forefoot width, RCSP and forefoot to rearfoot angle. Results indicated accurate representation of elementary foot morphology within the plaster images. The comparative study examined the between and within group differences in measures of foot length and width, and in measures above the support surface (heel inclination angle, forefoot to rearfoot angle, normalized arch height, height of the widest point of the heel) in the two load conditions. Results of measures from plaster images identified that hypermobile children have different barefoot weight bearing foot morphology above the support surface than non-hypermobile children, despite no differences in measures of foot length or width. Based upon the differences in components of control of posture and gait in the hypermobile group, identified in Study One and Study Two, the final study (Study Three), using the same subjects, tested the immediate effect of specifically designed custom-made foot orthoses upon balance and gait of hypermobile children. The design of the orthoses was evaluated against the direct measures and the measures from plaster images of the feet. This ascertained the differences in morphology of the modified casts used to mould the orthoses and the original image of the foot. The orthoses were fitted into standardized running shoes. The effect of the shoe alone was tested upon the non-hypermobile children as the non-therapeutic equivalent condition. Immediate improvement in balance was noted in single leg stance and CoP displacement in the hypermobile group together with significant immediate improvement in the percentage of gait phases and in the percentage of the gait cycle at which maximum plantar flexion of the ankle occurred in gait. The neuro-muscular and musculo-skeletal characteristics of children with joint hypermobility are different from those of non-hypermobile children. The Beighton, Solomon and Soskolne (1973) screening criteria successfully classified joint hypermobility in children. As a result of this study joint hypermobility has been identified as a variable which must be controlled in studies of foot morphology and function in children. The outcomes of this study provide a basis upon which to further explore the association between joint hypermobility and neuro-muscular and musculo-skeletal conditions, and, have relevance for the physical education of children with joint hypermobility, for footwear and orthotic design processes, and, in particular, for clinical identification and treatment of children with joint hypermobility.

In children, joint hypermobility (typified by structural instability of joints) manifests clinically as neuro-muscular and musculo-skeletal conditions and conditions associated with development and organization of control of posture and gait (Finkelstein, 1916; Jahss, 1919; Sobel, 1926; Larsson, Mudholkar, Baum and Srivastava, 1995; Murray and Woo, 2001; Hakim and Grahame, 2003; Adib, Davies, Grahame, Woo and Murray, 2005:). The process of control of the relative proportions of joint mobility and stability, whilst maintaining equilibrium in standing posture and gait, is dependent upon the complex interrelationship between skeletal, muscular and neurological function (Massion, 1998; Gurfinkel, Ivanenko, Levik and Babakova, 1995; Shumway-Cook and Woollacott, 1995). The efficiency of this relies upon the integrity of neuro-muscular and musculo-skeletal components (ligaments, muscles, nerves), and the Central Nervous System’s capacity to interpret, process and integrate sensory information from visual, vestibular and proprioceptive sources (Crotts, Thompson, Nahom, Ryan and Newton, 1996; Riemann, Guskiewicz and Shields, 1999; Schmitz and Arnold, 1998) and development and incorporation of this into a representational scheme (postural reference frame) of body orientation with respect to internal and external environments (Gurfinkel et al., 1995; Roll and Roll, 1988). Sensory information from the base of support (feet) makes significant contribution to the development of reference frameworks (Kavounoudias, Roll and Roll, 1998). Problems with the structure and/ or function of any one, or combination of these components or systems, may result in partial loss of equilibrium and, therefore ineffectiveness or significant reduction in the capacity to interact with the environment, which may result in disability and/ or injury (Crotts et al., 1996; Rozzi, Lephart, Sterner and Kuligowski, 1999b). Whilst literature focusing upon clinical associations between joint hypermobility and conditions requiring therapeutic intervention has been abundant (Crego and Ford, 1952; Powell and Cantab, 1983; Dockery, in Jay, 1999; Grahame, 1971; Childs, 1986; Barton, Bird, Lindsay, Newton and Wright, 1995a; Rozzi, et al., 1999b; Kerr, Macmillan, Uttley and Luqmani, 2000; Grahame, 2001), there has been a deficit in controlled studies in which the neuro-muscular and musculo-skeletal characteristics of children with joint hypermobility have been quantified and considered within the context of organization of postural control in standing balance and gait. This was the aim of this project, undertaken as three studies. The major study (Study One) compared the fundamental neuro-muscular and musculo-skeletal characteristics of 15 children with joint hypermobility, and 15 age (8 and 9 years), gender, height and weight matched non-hypermobile controls. Significant differences were identified between previously undiagnosed hypermobile (n=15) and non-hypermobile children (n=15) in passive joint ranges of motion of the lower limbs and lumbar spine, muscle tone of the lower leg and foot, barefoot CoP displacement and in parameters of barefoot gait. Clinically relevant differences were also noted in barefoot single leg balance time. There were no differences between groups in isometric muscle strength in ankle dorsiflexion, knee flexion or extension. The second comparative study investigated foot morphology in non-weight bearing and weight bearing load conditions of the same children with and without joint hypermobility using three dimensional images (plaster casts) of their feet. The preliminary phase of this study evaluated the casting technique against direct measures of foot length, forefoot width, RCSP and forefoot to rearfoot angle. Results indicated accurate representation of elementary foot morphology within the plaster images. The comparative study examined the between and within group differences in measures of foot length and width, and in measures above the support surface (heel inclination angle, forefoot to rearfoot angle, normalized arch height, height of the widest point of the heel) in the two load conditions. Results of measures from plaster images identified that hypermobile children have different barefoot weight bearing foot morphology above the support surface than non-hypermobile children, despite no differences in measures of foot length or width. Based upon the differences in components of control of posture and gait in the hypermobile group, identified in Study One and Study Two, the final study (Study Three), using the same subjects, tested the immediate effect of specifically designed custom-made foot orthoses upon balance and gait of hypermobile children. The design of the orthoses was evaluated against the direct measures and the measures from plaster images of the feet. This ascertained the differences in morphology of the modified casts used to mould the orthoses and the original image of the foot. The orthoses were fitted into standardized running shoes. The effect of the shoe alone was tested upon the non-hypermobile children as the non-therapeutic equivalent condition. Immediate improvement in balance was noted in single leg stance and CoP displacement in the hypermobile group together with significant immediate improvement in the percentage of gait phases and in the percentage of the gait cycle at which maximum plantar flexion of the ankle occurred in gait. The neuro-muscular and musculo-skeletal characteristics of children with joint hypermobility are different from those of non-hypermobile children. The Beighton, Solomon and Soskolne (1973) screening criteria successfully classified joint hypermobility in children. As a result of this study joint hypermobility has been identified as a variable which must be controlled in studies of foot morphology and function in children. The outcomes of this study provide a basis upon which to further explore the association between joint hypermobility and neuro-muscular and musculo-skeletal conditions, and, have relevance for the physical education of children with joint hypermobility, for footwear and orthotic design processes, and, in particular, for clinical identification and treatment of children with joint hypermobility.

The current study aimed to investigate influences of rigid Ankle Foot Orthoses (AFOs) on gait in children with Cerebral Palsy (CP), immediate effects of tuning of AFO-FC (AFO-Footwear Combination) on gait of children with CP, short-term effects of tuning of AFO-FC on gait, muscle and joint characteristics and quality of life in children with CP, and the feasibility of conducting a larger trial. The study included 11 healthy children and 8 children with CP. Outcome measurements included sagittal plane kinematics and kinetics derived using 3D motion analysis, Gait Deviation Index (GDI), physical examination, and quality of life using the PedsQL™ questionnaire. Data from healthy children demonstrated influences of shoes on gait parameters and the role of the ankle joint in adapting to various wedges and rockers during gait. When studying children with CP, beneficial effects of rigid AFO-FC on gait parameters were evident; these were thought to relate to the appropriateness of the AFO-FC and familiarisation with the prescription. Immediate effects of tuning varied according to gait patterns previously demonstrated with non-tuned AFO-FC; benefits to knee kinematics and kinetics were largely seen in legs with extended knee gait, followed by jump knee gait, and with poorest responses in legs with crouch knee gait. Short-term effects of tuning were evident when comparing measurements taken before and after two-to-four months of wearing the tuned AFO-FC. Barefoot walking demonstrated significantly improved walking speed. Stride-length improved when comparing tuned AFO-FC at baseline with the tuned AFO-FC following the intervention period. No short-term changes were seen in PedsQL™ scores, muscle and joint characteristics, and GDI. Feasibility issues were also identified. It was concluded from this exploratory trial that tuning of AFO-FC improved gait for children with CP, although initial gait pattern affected the amount of benefit. This was evident immediately after tuning and some parameters improved further after short-term intervention. A randomised controlled trial is required; power analysis indicates the need for a larger sample of 18 in each group to detect change in GDI with a medium effect size and at a power of 0.8 and p <0.05.

Bakgrund: De intrinsica fotmusklerna (IFM) har potential att påverka idrottslig prestation som hopp, sprint samt balans direkt genom påverkan av muskelstyrkan eller indirekt genom påverkan på det mediala-longitudinella fotvalvet. Ett växande antalet studier visar samband mellan träning av IFM och idrottslig prestation, dock råder ingen konsensus och motstridiga resultat finns. Syfte: Syftet med studien var att kritiskt granska litteratur och undersöka det aktuella vetenskapliga kunskapsläget för sambandet mellan muskelstyrka i IFM och friska individers sprint- och hopprestanda samt balans. Metod: En litteratursökning med noga valda sökord genomfördes i fyra databaser. Efter genomgång av in- och exkluderingskriterier inkluderades 10 studier vilka kvalitetsmässigt bedömdes med Joanna Briggs Institute granskningsmall för tvärsnittsstudier. En narrativ syntetiserande analys genomfördes. Resultat: Kvalitén i inkluderade studier bedömdes i genomsnitt vara medelgod. Det som främst drog ner betyget var hanteringen av confounders och användandet av ej valida mätinstrument. Generellt visade inkluderade studier på ett samband mellan tåflexor styrka/storlek och hopp- och sprintprestanda samt balans. Svårigheten att isolerat mäta IFM försvårar möjligheten att utreda IFMs betydelse för inkluderade studiers utfallsmått. Slutsats: Genomförd litteraturstudie visar möjliga samband mellan styrka/tåflexorstorlek och prestation i hopp och sprint såväl som balans. För att nå en ökad förståelse för hur IFM påverkar idrottslig prestation och balans behövs en större kunskap om hur IFM styrka direkt eller indirekt kan mätas isolerat och hur muskelstorlek kan översättas till styrka. Genomförd litteraturgranskning stödjer ett redan identifierat behov av valida mätinstrument för att nå en ökad förståelse av IFMs betydelse för idrottslig prestation och balans.
Background: The intrinsic foot muscles (IFM) have the potential to improve sprint, jump and balance performance by direct muscle power or indirectly by supporting the medial longitudinal arch. A growing number of studies show the association between exercising the IFM and athletic performance. However, there is no consensus if athletes can benefit from IFM training and inconsistent results are published. Aim: The aim of this study was to conduct a critical systematic review to evaluate the current knowledge of the association between IFM strength and performance in jump sprint and balance in healthy individual’s. Methods: Four data bases were searched for eligible studies. After screening for exclusion and inclusion criteria ten studies were included. The scientific quality was analyzed using the Joanna Briggs Institute ”Critical Appraisal tools” for Cross Sectional Studies, and a narrative synthesis was conducted. Results: The average quality score for the included studies was “moderately good”. The main reason for the low scores was insufficient attention to confounders and the use of non-valid instruments. An association was found in most of the studies between toe flexor strength/size and jump, sprint and balance performance. Difficulties in selectively measuring the IFM activity complicated the possibility to evaluate the impact of IFM on studied outcome measures. Conclusion: The presented study shows an association between toe flexor strength/size and athletic performance. However, to understand how IFM strength training affects athletic performance, both directly and indirectly, more studies focused on how to measure the IFM using valid methods for isolated IFM measures of strength and size is needed.

Les orthèses de propulsion mandibulaire sont fréquemment utilisées en orthopédie-dento-faciale pour stimuler le développement de ce maxillaire. Le déplacement antérieur de son centre de gravité et les tensions musculaires et viscérales (appareil aéro-digestif) qui apparaissent alors sont susceptibles d’influer sur la posture du sujet debout. Pour le déterminer, une étude stabilométrique a été menée. Elle permet de mettre en évidence les variations de position de la projection au sol du centre de gravité du corps (PGv). Les effets du port de trois orthèses imposant une quantité de propulsion différente ont été analysés, comparés entre eux et à la situation sans orthèse portée. Ces résultats ont été complétés par ceux issus d’une étude électromyographique, menée pour détecter les muscles mis en jeu dans le contrôle de l'équilibre. L’ensemble de ces expérimentations montre principalement une perte du contrôle postural (augmentation des oscillations de PGv) et un repositionnement plus postérieur du centre de gravité corporel lors d’avancement mandibulaire important, et ce d’autant plus que l’orthèse portée provoque peu de désocclusion inter-maxillaire. Une activité accrue des muscles fléchisseurs dorsaux du pied, de la hanche, du cou et extenseurs du rachis lombaire accompagne ces variations de position de PGv. Une hypothèse d'adaptation posturale en réaction à l'avancement de la mandibule est formulée ainsi qu’une critique et une évolution du protocole d’étude
Mandibular propulsion splints are frequently used in dento-facial orthopedics so as to stimulate the development of this maxilla. Consequently, we can notice that its centre of gravity moves forward but also that visceral (the aerodigestive apparatus) and muscle tensions appear. These elements are likely to have an influence on the position of a person standing. A stabilometric study was carried out to highlight the changes in the projection onto the ground of the body centre of gravity (PGv). We analysed and compared the effects of the wearing of three different splints (each of which required a different level of propulsion). But a comparison between these results and the normal situation (no splint worn) was also drawn. Moreover, an electromyographic study was carried out to find out which muscles were stimulated in the balance control. Its results were then added to those of the stabilometric study. These experiments mainly show that we lose control of the postural equilibrium (increase of the PGv oscillations). It also shows that when the mandible is significantly moved forward, the body center of gravity goes back into a more posterior position. This is all the more true as the splint worn does not cause much inter-maxillar disocclusion. The back flexor muscle of the foot, of the hip, of the neck and the extensor muscle of the lumbar rachis are greatly stimulated in the variations of the PGv. A postural adaptation to the mandibular advancement is hypothetically expressed, together with a criticism and an evolution of the study procedure

Limited knowledge of the neuromechanical response to use of an ankle foot orthosis-footwear combination (AFO-FC) has created a lack of consensus in understanding orthotic motion control as a therapeutic treatment. Lack of consensus may hinder the clinician’s ability to target the motion control needs of persons with movement impairment (e.g., peripheral nerve injury, stroke, etc.). Some evidence suggests a proportional relationship between joint motion and neuromuscular activity based on the notion that use of lower limb orthoses that constrain joint motion may invoke motor slacking and decreasing levels of muscle activity. Use of AFO-FCs likely alters the biomechanical and neuromuscular output as the central control system gradually forms new movement patterns. If there is proportional relationship between muscle activation and joint motion, then it could be examined by quantifying joint motion and subsequent neuromuscular output. Considering principles of neuromechanical adjustment, my general hypothesis examines whether orthotic control of lower limb motion alters neuromuscular output in proportion to the biomechanical output as a representation of the limb’s dynamics are updated by the neural control system. The rationale for this approach is that reference knowledge of the neuromechanical response is needed to inform clinicians about how a person responds to walking with motion controlling devices such as ankle foot orthoses combined with footwear. In the first line of research, I hypothesize that a newly developed AFO which maximizes leverage and stiffness will constrain the talocrural joint and alter joint kinematics and ground reaction force patterns. To answer the hypothesis, I sampled kinematics and kinetics of healthy subjects’ treadmill walking using an AFO-FC in a STOP condition and confirmed that the AFO substantially limited the range of talocrural plantarflexion and dorsiflexion motion to 3.7° and in a FREE condition maintained talocrural motion to 24.2° compared to 27.7° in a CONTROL (no AFO) condition. A follow up controlled static loading study sampled kinematics of matched healthy subjects limbs and cadaveric limbs in the AFO STOP and FREE conditions. Findings revealed healthy and cadaveric limbs in the AFO STOP condition substantially limited their limb segment motion similar to matched healthy subjects walking in the STOP condition and in the AFO FREE condition healthy and cadaveric limbs maintained similar limb segment motion to matched healthy subjects walking in the FREE condition. In a second line of research, I hypothesize that flexibility of a newly developed footwear system will allow normal walking kinetics due to the shape and flexibility of the footwear. To answer the hypothesis, I utilized a curved-flexible footwear system integrated with an AFO in a STOP condition and sampled kinematics and kinetics of healthy subjects during treadmill walking. Results revealed subjects elicited similar cadence, stance and swing duration and effective leg-ankle-foot roll over radius compared to walking in the curved-flexible footwear integrated with the AFO in a FREE condition and a CONTROL (no AFO) condition. To validate rollover dynamics of the curved-flexible footwear system, a follow up study of healthy subjects’ treadmill walking in newly developed flat-rigid footwear system integrated with the AFO in a STOP condition revealed interrupted leg-ankle-foot rollover compared to walking in curved-flexible footwear in STOP, FREE and CONTROL conditions. In a third line of research, I hypothesize that use of an AFO that limits talocrural motion in a STOP condition will proportionally reduce activation of Tibialis Anterior, Soleus, Medial and Lateral Gastrocnemii muscles compared to a FREE and CONTROL condition due to alterations in length dependent representation of the limb’s dynamics undergoing updates to the central control system that modify the pattern of motor output. To answer the question, the same subjects and AFO-footwear presented in the first two lines of research were used in a treadmill walking protocol in STOP, FREE, and CONTROL conditions. Findings revealed the same subjects and ipsilateral AFO-footwear system presented in Aim 1 exhibited an immediate yet moderate 30% decline in EMG activity of ipsilateral Soleus (SOL), Medial Gastrocnemius (MG) and Lateral Gastrocnemius (LG) muscles in the STOP condition compared to the CONTROL condition. The reduction in EMG activity in ipsilateral SOL, MG and LG muscles continued to gradually decline during 15 minutes of treadmill walking. On the contralateral leg, there was an immediate yet small increase of 1% to 14% in EMG activity in SOL, MG, LG muscles above baseline. After 10 minutes of walking, the EMG activity in contralateral SOL, MG and LG declined to a baseline level similar to the EMG activity in the contralateral CONTROL condition. These collective findings provide compelling evidence that the moderate 30% reduction in muscle activation exhibited by subjects as they experience substantial (85%) constraint of total talocrural motion in the AFO STOP condition is not proportionally equivalent. Further, the immediate decrease in muscle activation may be due to a reactive feedback mechanism whereas the continued decline may in part be explained by a feedforward mechanism. The clinical relevance of these findings suggests that short term use of orthotic constraint of talocrural motion in healthy subjects does not substantially reduce muscle activation. These preliminary findings could be used to inform the development of orthoses and footwear as therapeutic motion control treatments in the development of motor rehabilitation protocols.

An inherited muscle hypertrophy in sheep is caused by the callipyge gene (CLPG) located on ovine chromosome 18. It has been suggested that this gene is a single autosomal dominant gene. Animals expressing the callipyge gene show increased muscling in the pelvic and torso regions of the body and, thus, have been given the phenotype- descriptive name callipyge (from Greek calli-beautiful; pyge-buttocks). In this study 21 wether lambs, the offspring of callipyge rams (genotype CLPG /clpg) and normal Rambouillet ewes (genotype clpg/clpg), were used to determine the difference s in muscle fiber type percentages, composition, and tenderness between normal and callipyge lambs . Eleven of these lambs showed muscle hypertrophy typical of the callipyge phenotype; 10 were classified as normal . Several histochemical, biochemical , and physical measures were examined in order to study changes in the physiology and biochemistry of some economically important muscles. When compared to normal lambs, the callipyge lambs have a larger (P < .05) average percentage of fast-twitch glycolytic (FG) muscle fibers and smaller average percentages of fast-twitch oxidative and glycolytic (FOG) and slow-twitch oxidative (SO) muscle fibers in both the longissimus and gluteus medius muscles. The diameter of the fast-twitch muscle fibers was larger in the callipyge group, but slow-twitch fibers were smaller than those of normal lambs. No differences were observed in the supraspinatus muscle of the normal and callipyge groups. Thus there is an indication of a differential effect of the callipyge gene among muscles of the callipyge lambs. The semitendinosis muscles of both the callipyge and normal groups were dissected from the carcasses. This muscle was larger (P < .01) and contained more protein in the callipyge lambs than in the normal lambs. However, the callipyge semitendinosis muscle did not have a significantly higher content of DNA than the normal lamb semitendinosis, suggesting that the muscle hypertrophy is not associated with an increase in muscle nuclei. The protein-to-DNA ratio was larger (P < .05) in the semitendinosis muscle of callipyge lambs than in the normal lambs. Protein-to-RNA and RNA-to-DNA ratios were similar; this suggests that the semitendinosis muscle was enlarged without increased translational or transcriptional activity. Samples from the callipyge longissimus and gluteus medius muscles had RNA, DNA, and protein ratios similar to those of the semitendinosis muscle, suggesting a similar mode of action for muscle enlargement in other muscles affected by this gene. Loin chops from the callipyge lambs had lower tenderness scores (P < .01) as measured by the Wamer-Bratzler shear force and myofibril fragmentation index (MFI). However, aging increased MFI scores and decreased shear scores (P < .0 l) of the callipyge lamb chops . The normal lamb chops also had decreased shear and increased MFI scores following the aging period. The loin chops from the callipyge lambs also tended to be less red (P < .1) than chops from normal animals as measured by Hunter 'L,' 'a,' and 'b' colorimeter scores.

Bien qu’il soit recommandé de pratiquer tout au long de sa vie une activité physique régulière pour se maintenir en bonne santé, peu d’études portent sur les modifications des patrons locomoteurs lors de la répétition de séances à 2 ou 3 jours d’intervalle. Lorsqu’elles sont intenses ou inhabituelles, les formes naturelles de locomotion pédestre – dites de type cycle étirement-détente (CED) – se caractérisent par des perturbations structuro-fonctionnelles et proprioceptives qui peuvent perdurer plusieurs jours. Ces déficiences sont autant de sources de risques accrus de blessures lors de la répétition d’une pratique sportive. Ce travail doctoral a pour objectif (i) d’examiner les effets immédiats et retardés d’exercices épuisants de type CED sur les paramètres neuromécaniques de la locomotion humaine en conditions de marche, de course et de sauts et (ii) d’étudier l’influence combinée d’une pratique pieds nus vs. pieds chaussés. Nos résultats ne révèlent pas de modification significative des patrons locomoteurs en phase de récupération immédiate (post-exercice) mais démontrent l’intervention de stratégies compensatrices et/ou protectrices en phase de récupération retardée (2ème jour posteffort). Ces stratégies diffèrent entre les conditions de marche et de course. Nos travaux soulignent également l’importance de discriminer les stratégies adoptées dès la première minute de l’exercice des ajustements ultérieurs apparaissant pendant la phase dite d’optimisation du CED. Par contre, les différences observées entre les conditions de course pieds nus vs. pieds chaussés restent étonnamment similaires avec la fatigue. Le port de chaussures se traduit par une réduction des chocs d’impact mais également par une restriction des mouvements naturels du pied et par une éversion accrue dont il conviendrait d’étudier les conséquences lors de la répétition en état de fatigue d’exercices de plus longue durée
Although lifelong practice of moderate amounts of regular physical activity is recommended to ensure a healthy living state, little is know about the modifications of the locomotion patterns when repeating exercises every 2 to 3 days. Intense or unaccustomed stretch-shortening cycle (SSC) forms of ground locomotion are characterized, however, by structuro-functional and proprioceptive impairments that may last for a few days. These impairments may then be expected to increase the risk of injury. The present work aimed (i) to examine the acute and delayed SSC fatigue effects on the neuro-mechanical gait characteristics in walking, running and jumping conditions and (ii) to study the combined influence of a barefoot vs. shod gait condition. Our results did not reveal any modification of the locomotion patterns in the acute recovery phase (post-exercise), but demonstrated compensatory and/or protective strategies in the delayed phase (2 days post-exercise). The observed strategies differed significantly in walking and running. Our results emphasized also the need to differentiate the strategies occurring within the first minute of exercise from the subsequent adjustments related to the progressive SSC pattern optimization. Surprisingly, the observed differences between the barefoot and shod running conditions remained quite independent of the fatigue state. The shod running condition was thus found to attenuate ground impact transmission, but it resulted also in restricted natural foot motions and increased eversion that should be worth re-examining when repeating exercises of longer duration

[Truncated abstract] It is well established that fish, amphibians and reptiles recovering from physical activity of near maximal intensity can replenish completely their muscle glycogen stores in the absence of food. In contrast, the extent to which these stores are replenished under these conditions in humans has been reported in all but one study to be partial. This implies that a few consecutive bouts of intense exercise might eventually lead to the sustained depletion of the muscle glycogen stores in humans if food is unavailable, thus limiting their capacity to engage in fight or flight behaviors unless mechanisms exist to protect muscle glycogen against sustained depletion. The objective of Study 1 was to test this prediction. Eight participants performed three intense exercise bouts each separated by a recovery period of 75 minutes. Although only 53% of muscle glycogen was replenished after the first exercise bout (postexercise and post-recovery glycogen levels of 246 ± 25 and 320 ± 36 mmol.kg-1 dry mass, respectively), all the glycogen mobilised during the second and third bouts was completely replenished during the respective recovery periods, with glycogen reaching levels of 319 ± 29 mmol.kg-1 dry mass after recovery from the third bout. These findings show that humans are not different from other vertebrate species in that there are conditions where humans have the ability to completely replenish without food intake the muscle glycogen mobilised during exercise. The results of our first study raise the intriguing possibility that humans have pre-set muscle glycogen levels that are protected against sustained depletion, with the extent to which muscle glycogen stores are replenished after exercise being dependent on the amount of glycogen required to attain those protected levels. ... During recovery, glycogen levels in the NORM group increased by more than ~50% and reached levels close to those alleged to be protected (189 ± 21 mmol.kg-1 dry mass), whereas no glycogen was deposited in the HCHO group. The sustained post-exercise activation of glycogen synthase, the transient fall in whole body carbohydrate oxidation rate, the increased mobilisation of body proteins, and the prolonged elevation in NEFA levels most probably played important roles in enabling glycogen synthesis in the NORM group. In conclusion, this thesis shows for the first time that there are some conditions (e.g. low pre-exercise muscle glycogen levels) where humans recovering from intense exercise have the capacity, like other species, to replenish completely their muscle glycogen stores from endogenous carbon sources. This study also suggests that humans protect preset levels of muscle glycogen against sustained depletion and at levels high enough to support at least one maximal sprint effort to exhaustion. Evidence is also provided for the existence of a feedback mechanism whereby glycogen below their protected levels mediate the activation of glycogen synthase to restore the depleted muscle glycogen stores back to their protected levels. Our findings, however, leave us with a number of novel unanswered questions which clearly show that the regulation of glycogen metabolism is far from the simple process generally depicted in most textbooks of biochemistry.

Authenticity issues and fraudulent practices regarding animal products are affecting consumer confidence. Verifying the description, composition, processing or origin of foods can be challenging. To explore British and Kurdish consumers’ perceptions of kebab meat products, focus groups and questionnaire surveys were applied. About 40% of participants in the UK tend to purchase fewer processed meats after the European horsemeat scandal. Issues raised by participants indicated their concerns about the declaration of species, meat content, and other ingredients incorporated in kebab and other meat products. Lack of consumer trust has been linked to authenticity issues. Reactions towards the addition of fat-replacing inulin were positive by more than half of respondents. A further study aimed to investigate the effect of commercial inulin (CI) and Jerusalem artichoke (JA) tubers as fat replacers on the eating quality and overall acceptability of kebabs. Inulin flour prepared from JA by a simple protocol presented advantages with about 10% higher cooking yield and overall acceptability when compared with CI. Levels of inulin as low as 0.5% were detected in meat products using enzymatic assay, which could be relevant to detect additives and enforce labelling requirements. The authenticity (origin and species) was investigated in fish samples from commercial markets in Erbil, Kurdistan Region of Iraq (KRI). The declared fish species was checked using DNA barcoding with Cytochrome b region. A 10 % rate of mislabelling occurred only for wild common carp (Cyprinus carpio), with 9 out of 12 discovered to be the related species goldfish (Carassius auratus), which was deemed to be accidental rather than deliberate fraud. Such occurrences were from street markets and fishmongers, while none were from supermarkets. Wild and farmed common carp samples were not discriminated by DNA barcoding. Further fingerprinting using compositional profile and nearinfrared spectroscopy (NIRS) together with chemometric analysis aimed to predict composition and discriminate between wild and farmed common carp and species identity. NIRS-predictions of composition and some macrominerals of fish have a strong correlation with the references. NIRS with chemometric analysis is promising, but were not satisfactorily accurate for micro-minerals. Even with no clear solution from principal component analysis (PCA), NIRS-PCA may contribute to discriminating sample groups, but not for authentication when used alone. Having reliable techniques for authentication of food of animal origin may discourage deliberate replacement in retail, wholesale and international trade, and may contribute to reductions in food mislabelling, therefore protecting consumers from fraudulent practices.

Muscle foods/meat enhances bioavailability of non-heme iron form the diet. This effect is generally thought to be due to production of peptides, by gastro-intestinal digestion, which reduces/chelate the iron in upper intestine. Dialyzable iron is widely used as an in-vitro indicator of iron bioavailability, and with few exceptions, correlates well with human studies. Human studies have used cooked meat to test the effect on iron, but little attention has been given to the effects of cooking. We studied the effect of heating chicken muscle on the production of dialyzable iron. Chicken breast muscle was homogenized and heated to the temperatures in the range of 130-195oF. The concentration of amino acid binding residues was determined in the heated samples. The samples were then mixed with ferric iron and digested with pepsin and pancreatin. Heating chicken muscle caused a large drop in sulfhydryl (-SH) content and a lesser but significant loss in histidine content, both of which increased progressively with temperature. At 165oF, considered a safe cooking temperature, the loss in –SH and histidine was 75% and 37%, respectively. Changes in dialyzable iron and dialyzable ferrous iron (often considered the best indicator of bioavailability) paralleled the drop in amino acid. Raw uncooked chicken muscle produced about 11 times as much dialyzable iron and 17 times as much dialyzable iron as the control but heating to 165oF reduced the values by 47% and 74% respectively. Heating to 195oF reduced caused a further drop in dialyzable iron values. Our result showed that cooking chicken muscle caused a large decrease in the production of dialyzable iron forms-especially in the ferrous form- and this is correlated with the loss in critical iron binding amino acids.

Visible and near infrared (NIR) reflectance and transmission spectra (400 - 2500 nm) of various flesh foods in various presentations were examined for qualitative and quantitative analysis. Discriminant functions for muscle types and animal species were included. Lamb muscles (n: 306), chicken breast and thigh muscles (n: 48), bull and steer muscles (n: 103), raw fish (n: 80), fish meal (n: 700) and fish oil (n: 160) samples were examined in the experiments. INTACT and MINCED presentation to the instrument were compared, as well as type of muscle (longissimus dorsi, infra spinatus, supra spinatus, semimembranosus, semitendinosus, rectus femoris), effect of sex and both longitudinal (LS) and transverse section (TS) of the muscle on the optical properties and Partial Least Squares (PLS) calibrations for gross composition. MINCED presentation to the instrument gave the best results for the NIRS calibrations in all the muscle tissues utilized, while, INTACT presentation showed poorer calibrations. Muscle type and sex affect the calibrations. Raw fish and fish by-products, both fish meal and oil had good NIRS calibrations for the twelve parameters analyzed. The results show that NIRS is acceptable as a method for determining gross composition in a wide variety of flesh foods in MINCED presentation. Principal component analyses (PCA) and Soft Independent Modelling of Class Analogy (SIMCA) were used for the authentication and classification between muscles and among animal species. The conclusions of this work are that NIRS can successfully predict chemical composition in different muscles in MINCED rather than INTACT presentation. Classifications using PCA and SIMCA were excellent tools to authenticate flesh foods.

Thesis (MSc Food Sc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: The microbial growth, colour stability and pH changes for black wildebeest (Connochaetes gnou) meat under chilled (4.2±0.8°C) vacuum storage were investigated. The investigation centred on the role of ultimate muscle pH on shelf life of the meat. Although bacterial growth was observed over time for both DFD (pH >6) and Normal (pH <6) meat, DFD meat exhibited higher growth rates for lactic acid bacteria (LAB), total viable counts (TVC) and total coliforms. This was attributed to the combination of high pH and possibly the depletion of glucose in the DFD muscles. On the other hand, the growth rate of total coliforms was less than what was observed for the other microorganisms tested. It was assumed that chilled vacuum storage in combination with the high levels of LAB inhibited the growth of total coliforms. Salmonella was not detected in any of the samples analysed. There were no changes in pH during the 12 days storage period for DFD meat whereas pH for Normal meat decreased towards the end of storage possibly due to lactic acid production by LAB. The colour changes were more noticeable in Normal meat (more browning) than in DFD meat after blooming for 30 min. The conclusion for this study was that DFD meat spoiled faster than Normal meat. The meat was further subjected to preservation by oregano essential oil (1% v·v-1). In this case, there was an initial inhibition of TVC, LAB and total coliforms. Furthermore, the growth rates for TVC and LAB were lower (p<0.05) in the oregano oil treatment group than in the control. For total coliforms however, there was only an initial inhibition observed and no effect on the growth rate. Addition of oregano essential oil also resulted in a significant lowering of meat pH. This may have added to the microbial inhibition observed. Based on TVC values, addition of oregano essential oil extended the shelf-life of black wildebeest meat by 3 days. At the beginning of the study, the lipid oxidation (TBARS) values were above the threshold for detection. Also, the percentage of metmyoglobin had exceeded the levels at which browning becomes visible. Therefore, conclusions on the effects of oregano essential oil on the colour and lipid oxidations were not made in this study. However, oregano essential oil inhibited microbial growth and stabilised TBARS throughout the 9 day storage period. Therefore there is potential to use oregano essential oil as a preservative for black wildebeest meat, although more research is needed.
AFRIKAANSE OPSOMMING: In hierdie studie word die mikrobiese groei, stabiliteit en pH kleur verandering ondersoek vir swartwildebeestevleis onder verkoelde (4.2 ± 0.8 ° C) vakuum berging. Die ondersoek is spesifiek gefokus op die rol van die eind-spier pH op die raklewe van die vleis. Alhoewel mikrobiese groei vir beide DFD (pH >6) en Normal (pH <6) vleis waarneembaar was met verloop van tyd, het die DFD vleis hoër groeitempo vir melksuurbakterieë (MSB) en totale lewensvatbare tellings (LVT) getoon. Dit was as gevolg van die kombinasie van hoë pH en die moontlikheid van die vermindering van die glukose in die DFD spiere. Aan die ander kant was dit waargeneem dat die groeikoers van die totale kolivormig bakterieë minder was, teenoor die ander mikro-organismes wat getoets was. Dit was aangeneem dat die verkoelde vakuum stoor die groei van die totale kolivormig bakterieë geïnhibeer het. Salmonella was nie opgespoor in enige van die geanaliseerde monsters nie. Daar was geen verandering in pH tydens die stoor tydperk vir DFD vleis nie, maar die pH vir normale vleis het tydens die einde van die stoor tydperk afgeneem. Die kleur verandering onder vakuum stoor was meer waarneembaar in die normale vleis as wat dit was in die DFD vleis. Die gevolgtrekking van hierdie studie was dat DFD vleis baie vinniger bederf teenoor normale vleis. Maar daar was variasie op die gewig van die oorspronklike mikrobiese lading en dit kon die bakteriese groeitempo van die normale vleis beïnvloed. Die vleis is verder behandel met oregano essensiële olie ( 1 % v·v-1) vir preservering . In hierdie geval, was daar 'n aanvanklike inhibisie van LVT, MSB en totale kolivormig bakterieë. Verder was die groeitempo vir LVT en MSB aansienlik laer (p<0.05 ) in die behandelings groep teenoor die in die kontrole . Vir die totale kolivormig bakterieë was daar egter net 'n aanvanklike inhibisie waargeneem en geen effek op die groeikoers nie. Die byvoeging van oregano essensiële olie het ook gelei tot 'n beduidende verlaging van die pH. Dit kon gelei het tot die mikrobiese inhibisie wat waar geneem was. Gebaseerd op die LVT, het die byvoeging van oregano essensiële olie gelei tot die verlenging van die swartwildebeeste vleis se raklewe met 3 dae. Aan die begin van hierdie studie was die lipied oksidasie (TBARS) waardes bo die drumpel van opsporing. Ook, die persentasie van metmyoglobin het die vlakke waarop verbruining sigbaar word, oorskry. Daar is potensiaal vir die gebruik van oregano essensiële olie as n middel vir die verlenging van swartwildebees vleis, maar nog navorsing is nodig.

Color and color components are important quality attributes for fresh channel catfish muscle. The objective of the present research was to obtain inside understanding regarding color distribution, color component stability and the pre-slaughter conditions influence on color and color components and other quality attributes. Catfish fillets were rendered to be paler and redder on iced storage; and paler, less red and less yellow by ice-water chilling process. Visual classified reddish catfish fillets had higher heme-protein content than white fillets and these pigments were derived mainly from hemoglobin. Pre-slaughter live fish chilling in ice water and bleeding at slaughter also slightly affected muscle color and total heme-protein content, but they were not the main factors for the reddish color on catfish muscle. Catfish hemoglobin autoxidation rate was similar at room and at refrigeration temperature. Myoglobin gene and hemoglobin beta gene were cloned and expressed in Eschericia coli cells in insoluble form. The myoglobin gene had an open reading frame of 444 nucleotides and translated into 147 amino acids with molecular weight of 16,909 and pI of 9.43. The myoglobin gene in vivo expression in white muscle was not affected by pre-slaughter chilling. Pre-slaughter chilling is a stressor to channel catfish and shortens the pre-rigor time postmortem; thus, it is not recommended in catfish processing.

Thesis (Ph. D.)--West Virginia University, 2001.
Title from document title page. Document formatted into pages; contains x, 152 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 173-178).

Liver off-flavor is a sporadic problem that limits the consumer acceptance of several beef chuck muscles, including the infraspinatus (flat iron steak). Residual blood hemoglobin is known to contribute to liver off-flavor development. This study was conducted to evaluate factors affecting development of liver off-flavor after cooking of beef chuck (shoulder) muscles. The study was conducted in three parts. The objective of part 1 was to determine effects of muscle (infraspinatus, longissimus dorsi, serratus ventralis, supraspinatus, teres major) and processing (with or w/o carcass electrical stimulation) on residual blood hemoglobin content and total pigment content of raw muscle and sensory characteristics after cooking to 71 or 82?C. The objective of part 2 was to evaluate the effect of antioxidant treatment and anaerobic packaging to possibly reduce the incidence of liver and other off-flavors of beef infraspinatus (IF) steaks. The objective of part 3 was to determine the effect of animal age (commercial grade; >42 months, compared to select grade; <30>months), antioxidant treatment, and anaerobic packaging on sensory characteristics of beef IF steaks. Among beef chuck muscles, the infraspinatus had highest mean liver flavor score of 2.08±1.00 where 2=slightly intense liver flavor. Other muscles (longissimus dorsi, serratus ventralis, supraspinatus, teres major) had mean liver flavor scores less than 2. Liver flavor score, myoglobin, hemoglobin, and total pigment content were higher (p<0.05) for infraspinatus muscle from older animals. Among select grade muscles, carcass electrical stimulation had no significant effect on liver flavor score. Rancid flavor scores were significantly increased from 1.34±0.65 to 1.58±0.84 as internal cook temperature increased from 71 to 82°C but mean TBA values as a measure of rancidity (0.25±0.15 and 0.29±0.13, respectively) were not affected by cook temperature. Antioxidant treatment significantly reduced TBA values, rancid, and liver flavor scores for aerobically packaged steaks (PVC or 80% O2-MAP) but had little effect on scores of steaks in anaerobic packaging (0.4% CO-MAP). Results of this study indicate that infraspinatus steaks from older animals are most likely to have objectionable liver, sour/grassy, or rancid flavors. Objectionable flavor scores were lower in steaks receiving antioxidant injection or packaged anaerobically in 0.4% CO-MAP.

Dietary restriction (DR) is the only known nutritional manipulation that can increase both lifespan and healthspan in a variety of species. Underlying these increases are improvements in metabolic health and reductions in cancer incidence. Despite these physiological improvements, the regulation of skeletal muscle mass is extremely sensitive to alterations in nutrients [reviewed in (Sharples et al., 2015)] and as such has been reported to reduce regenerative potential and increase atrophy in skeletal muscle cells and myotubes. Interestingly, the activation of Sirtuin1 (SIRT1) has been reported during DR and its reduction abrogates lifespan extension. Importantly, SIRT1 activation via resveratrol treatment has been indicated to be important in the presence of inflammatory stress (TNF-α) (Saini et al., 2012). Resveratrol supplementation has also improved survival and regeneration of skeletal muscle cells as well in muscle cell remodelling following oxidative stress (Bosutti and Degens, 2015). We therefore sought to create an in-vitro physiological model of DR by mimicking levels of glucose in the circulation and interstitium in-vivo in response to DR (Chapter 3) as well as optimising the activation and inhibition of SIRT1 using resveratrol and SIRT1 inhibitor, EX-527 respectively (Chapter 4). With our ultimate aim to investigate the potential role and mechanisms of the activation/inhibition of SIRT1 in ameliorating the degenerative/atrophic effect of DR in both differentiating myoblasts (Chapter 5) and mature myotubes (Chapter 6). Indeed, in Chapter 3 we present two models of reduced glucose; one reduced (medium/ MED) and the other blocked (LOW) differentiation and myotube hypertrophy. The former represented circulatory glucose blood levels (MED 1.13 g/L or 6.25 mM) and the latter interstitial represented glucose levels (LOW 0.56 g/L or 3.12 mM) of rodents under DR. In Chapter 4 we also suggest that within the in vitro muscle cell model, activation/inhibition of SIRT1 phosphorylation (western blot analysis) was thought to be most effective at 10 μM of resveratrol and 100 nM of EX-527 respectively. In chapter 5, we observed that resveratrol treatment did not improve fusion when administered to differentiating myoblasts. Resveratrol did however evoke increases in myotube hypertrophy under normal glucose conditions. Importantly resveratrol enabled improved myotube hypertrophy over an acute 24 h period when administered to existing mature myotubes in low glucose environments. If this finding translates to whole organisms and human populations it could provide healthspan improvements via reductions in fragility associated with loss of muscle mass in individuals undergoing dietary restriction. After this 24 h period resveratrol was unable to reduce myotube atrophy and the myotubes continued to atrophy, suggestive of a need for repeated resveratrol treatment to enable continued protection against muscle atrophy under low glucose conditions. SIRT1 activation increased Myogenic regulatory factor 4 (MRF4) gene expression under LOW glucose conditions which was associated with the observed improvements in myotube size at 24 h. Whereas, SIRT1 activation via resveratrol treatment in normal glucose conditions modulated increased gene expression of Myosin heavy chain 7 (MYHC7) coding for the slow isoform while inhibition of SIRT1 (EX-527) lead to reductions in gene expression of MYHC 1, 2 and 4, coding for faster IIx, IIa, IIb isoforms respectively. Perhaps suggesting that elevated SIRT1 was important in the activation of genes coding for slower myosin heavy chain isoforms. Furthermore, while SIRT activation via resveratrol did modulate increases in IGF-I gene expression, it did not appear to modulate energy sensing AMP activated protein kinase (AMPK) vs. growth related Protein 70 S6 Kinase (p70S6K) signalling pathways. However, SIRT1 inhibition increased AMPK activity in both low and normal glucose with corresponding mean reductions in p70S6K in normal glucose conditions. This indicates that perhaps normal SIRT1 activity was required for appropriate AMPK activation, which may therefore prevent the suppression of p70S6K and the corresponding reductions in myotube size observed in SIRT1 inhibitor conditions. Furthermore, during low glucose induced myotube atrophy resveratrol reduced gene expression of the negative regulator of muscle mass, myostatin and protein degradative ubiquitin ligase enzyme, MUSA1. Overall, SIRT1 activation via a single dose of resveratrol appears to have a role in acutely negating the effect of low glucose induced myotube atrophy and promoting myotube hypertrophy when glucose is readily available.

Although Nephrops norvegicus is the basis for a major European fishery, in comparison to other fisheries surprisingly few measures have been taken so far to assure a maximum postharvest quality and to gain a high quality product. Knowledge of early and late postmortem biochemical changes is poor and it is not known how ante- and peri-harvest stressors affect the postharvest product quality in N. norvegicus. Several quality parameters, such as rigor mortis, kvalue, trimethylamine (TMA), ammonia, oxidized lipids, the bacteria load and the pH are generally known to reflect quality. However, none of these parameters is established for N. norvegicus and research is needed to elucidate their importance in this species. The aims of this study were to expand the knowledge of postmortem biochemical changes and postcapture bacterial spoilage in N. norvegicus. Modified atmosphere packing was also applied in order to prolong and extend the shelf life of the product and quality was measured using the previously established parameters.

Doutoramento em Biologia - Biologia Marinha
European fisheries represent one of the leading economic activities in the world. Marine parasites with public health and industrial concern have become a key issue in major European markets, due to three main reasons: (1) the presence of a reported increasing number of allergic and gastrointestinal disorders caused by fish-borne parasitic infections, (2) the commercial impact and high economic losses due to fish rejections, and (3) the applicability of Regulation EC 178/2002, which states that “fish with visible parasites is unfit for human consumption”. Over the last few years, since the entry into force of European and Member States regulations on food and specifically fishery products, co-responsibility for food quality and safety has lain with food industry, which has introduced Hazard Analysis and Critical Control Points (HACCP) programs in all its actions concerning the food chain. Consequently, significant progresses have been achieved regarding the prevention of parasites in seafood products. However, there is a lack of consensus and standardization for parasite inspection at fishing companies, and no efficient and accurate modus operandi exists to be implemented and accepted by the industry as a routine technique. The EU legal framework defined by zoosanitary regulations, scientific opinions from the European Food Safety Authority (EFSA), as well as the European Hygiene Package among others, has provided a basis on which the fishing sector has focussed its activity. Accordingly, this dissertation has been driven by these considerations during the course of its execution. This context led us to carry out a meticulous horizon scanning under a multidisciplinary approach, as an overview tool in proactive risk management. This fundamental practice takes due account of the stringent requirements that new markets are demanding to fishing industry, and the lacks and needs of the fishing sector with regard to the impact of the most relevant parasites with public health and industrial concern. A comprehensive technical evaluation and laboratory testing of the official parasite detection methods evidenced low reliability within the two most commonly used qualitative inspection procedures in fish processing (i.e. candling, gross visual inspection). Consistent parallel research carried out, has given as a result innovative scientific developments for diagnostic purposes and for the optimization of the current detection procedures. These technological improvements have been presented in more accessible and manageable formats for their incorporation into self-control programs at the fishing industry. Furthermore, the huge amount of inspection work carried out in the most relevant fish species, has allowed reaching a deeper knowledge concerning three very important parasite groups that are impacting on fishing industry; microsporidians, anisakids and copepods. Finally, the design and application of two innovating tools for parasite management (a scoring system for predictive assessment of fish lots, and a transfer of knowledge model presented in web format), helpful for seafood producers, policy makers and general public, are good examples of how to contribute stimulating the exchanging of ideas among stakeholders and improving the inspection scheme. They are also the best approach for helping to convert scientific findings and technological advances into industrial and commercial success. Scientific excellence requires investment in R&D&I with regard to acquire and expand a sound scientific basis for policy and regulation on food safety, and also for helping fishing industry to achieve a preventing plan which provides added value products. The high national and international exporting activity carried out daily from the most important fishing ports of Portugal and from the fishing Port of Vigo, requires that strict control measures based on groundbreaking scientific advances, have to be incorporated into proactive selfinspections made by seafood companies. These measures must include effective preventing and corrective actions in the edible part of heavily infected fish species, thus guaranteeing products of the highest safety and quality to final consumers.
A indústria pesqueira Europeia é uma das principais atividades económicas do mundo. Os parasitas marinhos com relevância em termos de saúde pública e ao nível da indústria constituem uma questão crucial nos principais mercados Europeus, devido a três razões principais (1) a presença de um número crescente de perturbações alérgicas e gastrointestinais causadas por infecções parasitárias de origem alimentar, (2) o impacto comercial e as perdas económicas resultantes do elevado volume de rejeições, e (3) a aplicação do Regulamento (CE) 178/2002, segundo a qual “o pescado com parasitas visíveis é impróprio para consumo humano”. Durante os últimos anos, com a entrada em vigor dos regulamentos Europeus e dos Estados Membros sobre alimentos, e especificamente sobre os produtos da pesca, e uma vez que a corresponsabilidade da qualidade e da segurança dos alimentos compete à indústria, a indústria pesqueira incorporou os programas de Análise do Risco e Pontos de Controlo Críticos (HACCP) nas suas competências em relação à cadeia alimentar. Consequentemente, tudo isto permitiu alcançar progressos significativos relativos à prevenção dos parasitas nos produtos da pesca. No entanto, há uma falta de consenso e de normalização sobre o tipo de inspeção de parasitas nas companhias pesqueiras, e não existe um modus operandi preciso e eficiente que seja aceite e implementado como técnica de rotina pela indústria. O atual quadro jurídico da UE definido pelos regulamentos zoo sanitários, o parecer do painel científico da Autoridade Europeia para a Segurança dos Alimentos (AESA), bem como o pacote da Higiene Alimentar entre outros, proporcionaram uma base sobre a qual o sector das pescas centra a sua actividade. Por conseguinte, a presente dissertação foi direccionada por todas estas considerações no decurso da sua execução. Este contexto conduziu-nos a realizar uma prospecção meticulosa, inovadora e multidisciplinar, como ferramenta fundamental para uma abordagem integrativa e pró-activa de gestão de riscos, entrando em linha de conta com as principais exigências dos novos mercados em relação à indústria pesqueira, e com as carências e necessidades do sector da pesca em relação ao impacto dos parasitas mais relevantes aos níveis comercial e de saúde pública. A avaliação técnica e numerosos testes de laboratório exaustivos dos métodos qualitativos oficiais de detecção de parasitas mais utilizados no processamento do pescado (transiluminação, inspeção visual), demonstraram baixos níveis de fiabilidade. Trabalhos de investigação desenvolvidos em paralelo permitiram desenvolvimentos científicos inovadores, melhorias tecnológicas para fins de diagnóstico e a otimização dos procedimentos de detecção vigentes. Estas melhorias foram apresentadas num formato mais acessível, de mais fácil compreensão e manuseio para a sua inclusão nos programas de autocontrolo na indústria pesqueira. Por outro lado, o amplo trabalho de inspecção realizado nas espécies de peixe comerciais mais importantes permitiu chegar a um conhecimento mais aprofundado de três grupos importantíssimos de parasitas que estão a ter um impacto considerável sobre o sector das pescas; microsporídeos, anisaquídeos e copépodes. Finalmente, o desenvolvimento e aplicação prática de duas ferramentas inovadoras para a gestão de parasitoses (um sistema de avaliação preditiva em lotes de peixe, e um modelo de transmissão de conhecimento em formato web), úteis para as empresas pesqueiras, autoridades sanitárias e público em geral, revelaram-se bons exemplos de como se pode contribuir para estimular o intercâmbio de ideias entre as partes interessadas, como melhorar a eficácia dos sistemas de inspeção, e especialmente de como converter as descobertas científicas e os avanços tecnológicos em êxitos industriais e comerciais. A excelência científica requer investimentos em PD&I, a fim de adquirir e expandir uma base científica sólida para a política, vigilância e regulamentação da segurança dos alimentos, e também para ajudar as indústrias a alcançar um plano de prevenção de modo a que possam oferecer produtos de maior valor acrescentado. A intensa atividade diária de exportação nacional e internacional realizada nos mais importantes portos pesqueiros de Portugal e no porto de pesca de Vigo (Galiza), requer que medidas de controlo estritas, baseadas nos avanços tecnológicos e científicos mais recentes, sejam integradas nos programas pró-activos de auto-controlo das companhias pesqueiras. Ainda assim, estas medidas devem incluir ações corretivas eficazes e ações de prevenção, perante a detecção de infecções graves nas partes comestíveis dos peixes, garantindo assim aos consumidores finais produtos com o mais alto nível de qualidade e segurança.
La industria pesquera en Europa constituye una de las principales actividades económicas del mundo. Las parasitosis de origen marino con repercusiones comerciales e implicaciones en la salud pública se han convertido en un problema clave en los mercados europeos debido a tres motivos principales: (1) al incremento en el número de notificaciones de alergias y desórdenes gastrointestinales causados por infecciones parasitarias transmitidas tras el consumo de pescado, (2) al impacto comercial y las elevadas pérdidas económicas debidas a los rechazos por la presencia de parásitos visibles (y/o sus lesiones asociadas), y (3) a la aplicación del Reglamento CE 178/2002, el cual establece que “todo pescado visiblemente parasitado es considerado no apto para el consumo humano”. En los últimos años, a partir de la entrada en vigor de reglamentos específicos sobre los productos de la pesca (tanto a nivel europeo como a nivel de los Estados miembros), la corresponsabilidad de la calidad y seguridad alimentaria ha recaído sobre la industria alimentaria, que consecuentemente ha incorporado programas de Análisis de Peligros y Puntos Críticos de Control (APPCC) a todas sus actuaciones entorno a la cadena alimentaria. En consecuencia, todo ello ha comportado el logro de considerables avances concernientes a la prevención de los parásitos en productos marinos. Sin embargo, la ausencia de un modus operandi lo suficientemente eficiente y fiable en la inspección parasitaria como para ser implementado y aceptado por el sector pesquero como técnica de rutina, es fiel reflejo de la falta de consenso y estandarización existente entre las compañías pesqueras. El marco legal de la UE definido por los reglamentos zoosanitarios, las opiniones científicas de la Agencia Europea de Seguridad Alimentaria (AESA), y por el Paquete de Higiene Alimentaria entre otros, ha sentado las bases sobre las que el sector pesquero ha fundamentado su actividad, y en consecuencia, sobre las que el desarrollo de la presente tesis doctoral ha focalizado su atención. Este mismo contexto es el que nos ha llevado a realizar un meticuloso “horizon scanning” bajo un enfoque multidisciplinario y a modo de herramienta “radar”. Este instrumento resulta fundamental para la gestión proactiva de riesgos, y debe tener en cuenta las principales exigencias de los nuevos mercados de la industria pesquera, así como las carencias y necesidades del sector en relación al impacto de los parásitos con mayores implicaciones sanitarias y comerciales. La evaluación técnica y las exhaustivas pruebas de laboratorio realizadas en este trabajo para valorar la fiabilidad de los dos métodos cualitativos de detección oficiales más utilizados durante el procesado de pescado (candling e inspección visual) evidenciaron que estos procedimientos presentan un bajo nivel de fiabilidad. Las investigaciones ejecutadas en paralelo permitieron optimizar los métodos de detección de parásitos en productos de la pesca vigentes, así como desarrollar innovaciones tecnológicas con fines diagnósticos. Algunas de éstas han sido presentadas en un formato más accesible y manejable para facilitar su incorporación en los programas de autocontrol de las industrias pesqueras. Por otra parte, el amplio trabajo de inspección realizado con las especies de pescado de mayor interés comercial, permitió llegar a un conocimiento mucho más detallado de tres importantísimos grupos de parásitos que actualmente tienen un alto impacto sobre el sector; microsporidios, anisákidos y copépodos. Finalmente, el diseño, la creación y la aplicación práctica de dos herramientas innovadoras para la gestión de parasitosis (un sistema de evaluación predictiva en lotes de pescado, y un modelo de transferencia de conocimiento en formato web) útiles para las empresas pesqueras, las autoridades sanitarias, y los consumidores, han demostrado ser buenos ejemplos de cómo contribuir a estimular el intercambio de ideas entre las partes interesadas, a mejorar la eficacia del esquema de inspección, y sobre todo a convertir los hallazgos científicos y los avances tecnológicos en éxito industrial y comercial. La excelencia científica requiere inversión en I+D+i a fin de adquirir y expandir una base científica sólida para la normalización y vigilancia de la seguridad alimentaria, además de para ayudar a la industria pesquera a conseguir un plan de prevención que permita ofrecer productos de alto valor añadido. La intensa actividad diaria de exportación nacional e internacional que tiene lugar en el puerto pesquero de Vigo y en los puertos pesqueros más importantes de Portugal, requiere que las estrictas medidas de control basadas en los avances tecnológicos y científicos más recientes sean integradas en los programas proactivos de autocontrol de las empresas pesqueras. Asimismo, estas medidas deben incluir acciones preventivas y correctivas efectivas sobre la parte comestible de los peces gravemente parasitados, garantizando así, productos con e más alto nivel de calidad y seguridad para el consumidor final.

The muscle hypertrophy of lambs expressing the Callipyge phenotype is possibly linked to characteristics of their muscle satellite cells. Therefore, characteristics (proliferation, fusion %, and protein accretion) of cultured satellite cells isolated from the longissimus muscle of Callipyge (n = 3) and normal (n = 3) lambs were compared in this study. In the first experiment, we tested whether or not the lll proliferation rates differ for satellite cells isolated from Callipyge or normal sheep when cultured in the presence of different serum types (horse, normal lamb, or Callipyge lamb). The average population doubling time (PDT, h) during log phase growth was calculated for cells from each animal grown in each serum type. Population doubling time was not affected (P > .1) by the interaction of satellite cell type with serum type, or by satellite cell type. Unexpectedly, PDT was longer (P < .05) for satellite cells grown in Callipyge serum (22 h) than for cells grown in normal sheep serum (20 h) or horse serum (18 h). These results suggest that muscle hypertrophy of Callipyge lambs is not linked to intrinsic differences in satellite cell proliferation, although hypertrophy may be associated with a decreased proliferation induced by a factor in Callipyge serum. In the second experiment, we tested whether cell fusion, or protein accretion differ for cultured satellite cells isolated from Callipyge or normal sheep. DNA and protein were determined at 24, 48, 72, and 96 h after satellite cell cultures were induced to differentiate. Fusion percentage was determined in a Giemsa stained plate after 72 h in differentiation medium (Dulbecco's Modified Eagle Medium containing 1.5% of horse serum). Callipyge cultures tended (P = .14) to have higher fusion% than normal cultures exhibited, suggesting that muscle hypertrophy of Callipyge lambs may be linked to an increased tendency of satellite cells to fuse. Protein content (μg/well) and protein:DNA ratio (ng of protein/ng of DNA) were not affected by satellite cell type (P = .80 and P = .79, respectively). Thus, there was no evidence for a link between increased protein accretion and Callipyge hypertrophy.

Superchilling is a method that can be used to prolong the shelf life of foods by partial freezing. Knowledge of the effects of this method on both the shelf life and quality of foods is important in order to find optimal processing and storage conditions and is of great importance both for the industry and for the consumers. Different raw materials of muscle foods were studied with the purpose of creating a basis for further improvements of both the process and the storage conditions. Products from the commercially important species pork (both roasts and rib steaks), Atlantic salmon (both vacuum packed and wrapped fillets) and Atlantic cod (vacuum packed fillets) were chosen to represent different muscle foods.

Based on both sensory and microbial evaluations, the superchilled storage improved shelf life of pork roasts from 2 to 16 weeks, and shelf life might even be further prolonged if temperature is kept more constant. The H2S-producing bacteria in superchilled cod fillets did not exceed the limit of consumption during the whole storage period of six weeks, while the microbial shelf life of the ice chilled fillets was estimated to be 8 days after processing.

Quality changes have been studied with focus on biochemical and physiochemical properties. One of the major goals in meat and fish processing is the ability to retain water and it was observed that drip loss was lower in superchilled samples compared to traditionally chilled samples in all species studied. However, the subsequent liquid loss was higher both in pork roasts and in cod fillets.

The extractability of protein was used as a tool to monitor protein denaturation. It was found that myofibrillar proteins denatured more easily during superchilled than during traditionally chilled storage both in salmon and in cod fillets. This was confirmed by electrophoresis in salmon. The amount of free amino acids were higher in cod than in salmon and increased more during superchilled storage than during ice chilled storage indicating exoproteolytic activity during storage. Activities of cathepsins B and B + L in salmon fillets were relatively stable during the storage period in all storage groups, demonstrating that these enzymes are not deactivated at the selected storage temperatures and may therefore lead to softening during subsequent chilled storage.

In superchilled samples of all species studied, white spots emerged on the product surface. However, the appearance of spots did not correspond either to higher drip loss or to higher microbial growth on surface of these samples. On the contrary, the total plate counts of superchilled samples were lower than of the other storage groups. This observation also applied to iron agar counts on cod fillets. These findings are interpreted as a strong indication of that the spots most likely were not of microbial origin.

The optimal superchilling process and storage conditions remains to be found for the products studied. From the present results it is reasonable to suggest that optimal storage temperature for the vacuum packed salmon fillets is found between the superchilled temperatures in the present experiments. The quality both of the pork roasts and the cod fillets would probably benefit from a storage temperature slightly closer to 0 °C than those studied. It can also be assumed that the control of the superchilling process is more essential to cod than to salmon and pork. In addition, the properties of the raw material are crucial in order to obtain high quality of products after processing and storage.

Paper I-III are reprinted with kind permission from Elsevier, sciencedirect.com

Thesis (MSc)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: The objective of this study was to investigate the impact of season on the composition and quality of male and female blesbok (Damaliscus pygargus phillipsi) muscles (Longissimus dorsi, Biceps femoris, Semimembranosus, Semitendinosus, Infraspinatus and Supraspinatus). The latter was quantified on the chemical composition (moisture, protein, fat and ash contents), fatty acid profile, mineral composition and physical attributes (pH, colour, drip and cooking loss, water holding capacity and tenderness) of the selected muscles. All of the blesbok muscles had higher (p<0.01) mean protein contents (20.6 g.100 g-1 to 23.1 g.100 g-1) when the plane of nutrition was believed to be higher (spring of 2009). A strong negative correlation (r = – 0.82; p<0.01) existed between the moisture and protein contents of the blesbok muscles. The Longissimus dorsi muscle had the highest (p<0.01) mean intramuscular fat content (3.4 g.100 g-1) when the plane of nutrition was higher. The chemical composition of the Longissimus dorsi, Biceps femoris, Semitendinosus and forequarter muscles (Infraspinatus and Supraspinatus) was affected least by the seasonal differences in the plane of nutrition and activity levels of the blesbok at the study area. However, season had a larger impact on the chemical composition of the Semimembranosus muscle. Season did not have a significant impact on the fatty acid profile of blesbok muscles, but the difference in the fatty acid profiles between male and female muscles was significant. A Principal Component Analysis (PCA) bi-plot indicated that female blesbok muscles were associated with a higher saturated fatty acid (SFA) and mono-unsaturated fatty acid (MUFA) content. Male blesbok muscles had higher (p<0.01) proportions of total polyunsaturated fatty acids (PUFA) (40.15 ± 5.39) and polyunsaturated to saturated fatty acid ratios (P:S) (0.85 ± 0.18), in comparison to female muscles (27.18 ± 8.04 and 0.54 ± 0.20, respectively). Differences in the anatomical locations of the selected blesbok muscles furthermore influenced the fatty acid profiles. The less active Longissimus dorsi muscle had higher (p<0.05) total PUFA (38.34 ± 8.62), total omega-6 (ω6) PUFA (34.46 ± 7.83), total ω3 PUFA (3.44 ± 0.84) and P:S (0.85 ± 0.24) contents, in comparison to the Infraspinatus muscle (28.96 ± 8.65, 26.23 ± 7.86, 2.31 ± 0.70 and 0.56 ± 0.19, respectively) and Supraspinatus muscle (28.85 ± 9.23, 26.05 ± 8.24, 2.28 ± 0.76 and 0.55 ± 0.21, respectively). The hindquarter muscles (Biceps femoris, Semimembranosus and Semitendinosus) had intermediate fatty acid content. Season had an impact on the calcium and zinc contents of blesbok muscles. The calcium content was higher (p<0.05) in the muscles of the animals harvested in spring (6.92 ± 1.94) compared to winter (5.61 ± 1.79). The zinc content was higher (p<0.05) in the muscles of male blesbok harvested in winter (4.04 ± 1.70) compared to spring (3.41 ± 1.67). The mineral composition was furthermore significantly different between the selected blesbok muscles. The Biceps femoris muscle had the highest (p<0.05) potassium (183.25 ± 12.79), phosphorus (180.21 ± 10.36) and magnesium (32.18 ± 1.72) content, while the sodium and calcium content was highest in the forequarter muscles. The Longissimus dorsi muscle had the highest (p<0.05) iron (3.67 ± 0.51), but significantly lower zinc content (1.63 ± 0.28), in comparison to the forequarter muscles. The pH value ≈24 h post mortem was higher (p<0.05) in the Longissimus dorsi muscle of the animals harvested in spring (5.60) compared to winter (5.54). The CIE a* (14.63 ± 0.86) and chroma (17.09 ± 0.63) values were higher (p<0.05) for winter than for male blesbok meat in spring (13.62 ± 1.08 and 16.10 ± 1.03, respectively). The latter values were also higher (p<0.05) for male compared to female (13.49 ± 0.88 and 16.22 ± 0.98) blesbok meat, at the end of the mating season (winter). The forequarter muscles had higher chroma values in comparison with the hindquarter muscles, which had higher (p<0.01) hue-angle values. Season had no influence (p<0.05) on the drip loss percentages and tenderness of blesbok muscles. The drip loss percentages were lowest (p<0.05) in the Biceps femoris and Semimembranosus muscles. The Infraspinatus and Supraspinatus muscles had the lowest (p<0.01) Warner Bratzler shear force values (20.89 ± 3.23 and 24.90 ± 5.35 N, respectively). Seasonal differences in the chemical composition of blesbok muscles were statistically significant. However, these differences were numerically small and it is therefore debatable whether they are of any biological relevance relating to human nutrition. The differences in the fatty acid profile and mineral composition as well as the physical meat quality attributes of blesbok muscles were more attributed to differences in the anatomical locations of the selected muscles, as opposed to the impact of season or gender.
AFRIKAANSE OPSOMMING: Die doel van die studie was om die impak van seisoen op die samestelling en kwaliteit van blesbok (Damaliscus pygargus phillipsi) spiere (Longissimus dorsi, Biceps femoris, Semimembranosus, Semitendinosus, Infraspinatus en Supraspinatus) te bepaal. Die seisoenale impak was gekwantifiseer op die chemiese samestelling (vog-, proteïen-, vet- en asinhoud), vetsuurprofiel, mineraal samestelling en fisiese eienskappe (pH, kleur, drup- en kookverlies, water houvermoë en taaiheid) van die geselekteerde spiere. Met ʼn hoër voedingspeil (lente 2009) het elkeen van die spiere gemiddeld ʼn hoër (p<0.01) proteïeninhoud (20.6 g.100 g-1 tot 23.1 g.100 g-1) gehad. ‘n Sterk negatiewe korrelasie (r = – 0.82; p<0.01) het bestaan tussen die vog- en proteïeninhoud van die blesbokspiere. Met ʼn hoër voedingspeil het die Longissimus dorsi spier die hoogste (p<0.01) gemiddelde intramuskulêre vetinhoud (3.4 g.100 g-1) gehad. Seisoenale verskille in die voedingspeil en aktiwiteitsvlakke van dié blesbokke het minimale verskille in die chemiese samestelling van die Longissimus dorsi, Biceps femoris, Semitendinosus en voorkwartspiere (Infraspinatus en Supraspinatus) tot gevolg gehad. Daar was wel seisoenale verskille in die chemiese samestelling van die Semimembranosus spier. Seisoen het nie ʼn beduidende invloed op die vetsuurprofiel van die blesbokspiere gehad nie, maar daar was wel beduidende (p<0.05) verskille tussen geslagte. Soos aangedui deur ʼn hoofkomponent-analise (PCA) bi-plot, was die spiere van die vroulike blesbokke meer geassosieer met hoër versadigde en mono-onversadigde vetsuursamestellings. Die spiere van die manlike diere het hoër (p<0.01) proporsies poli-onversadigde vetsure (PUFA) (40.15 ± 5.39) asook hoër poli-onversadigde tot versadigde vetsuur verhoudings (P:S) gehad (0.85 ± 0.18) in vergelyking met die spiere van die vroulike diere (onderskeidelik 27.18 ± 8.04 en 0.54 ± 0.20). Die vetsuurprofiel van blesbokspiere was ook beïnvloed deur die anatomiese ligging van die spiere. Die minder aktiewe Longissimus dorsi spier het ʼn hoër (p<0.05) totale PUFA (38.34 ± 8.62), totale omega-6 (ω6) PUFA (34.46 ± 7.83), totale ω3 PUFA (3.44 ± 0.84) en P:S (0.85 ± 0.24) inhoud gehad in vergelyking met die Infraspinatus spier (onderskeidelik 28.96 ± 8.65, 26.23 ± 7.86, 2.31 ± 0.70 en 0.56 ± 0.19) en Supraspinatus spier (onderskeidelik 28.85 ± 9.23, 26.05 ± 8.24, 2.28 ± 0.76 en 0.55 ± 0.21). Die agterkwartspiere (Biceps femoris, Semimembranosus en Semitendinosus) het intermediêre vetsuursamestellings gehad. Seisoen het ʼn invloed op die kalsium- en sinkinhoud van die blesbokspiere gehad. In die lente het die spiere gemiddeld ʼn hoër (p<0.05) kalsiuminhoud gehad (6.92 ± 1.94), in vergelyking met dié van winter (5.61 ± 1.79). Die manlike spiere van die blesbokke wat in winter geoes is, het weer ʼn hoër (p<0.05) sinkinhoud (4.04 ± 1.70) in vergelyking met dié van die lente (3.41 ± 1.67) gehad. Verder het die mineraalinhoud van die geselekteerde blesbokspiere betekenisvol van mekaar verskil. Die Biceps femoris spier het die hoogste (p<0.05) kalium- (183.25 ± 12.79), fosfor- (180.21 ± 10.36) en magnesiuminhoud (32.18 ± 1.72) gehad. Die natrium- en kalsiuminhoud was hoër in die voorkwartspiere. Die Longissimus dorsi spier het die hoogste (p<0.05) ysterinhoud (3.67 ± 0.51) gehad. Laasgenoemde het ʼn beduidend laer sinkinhoud (1.63 ± 0.28) in vergelyking met die voorkwartspiere gehad. Die Longissimus dorsi spiere van die blesbokke wat in die lente geoes is, het gemiddeld hoër pH-waardes by ≈24 uur post mortem gehad (5.60) in vergelyking met die pH-waardes van dié spiere in winter (5.54). Die CIE a*- (14.63 ± 0.86) en chroma-waardes (17.09 ± 0.63) van die manlike blesbokspiere was hoër (p<0.05) in die winter as in die lente (onderskeidelik 13.62 ± 1.08 en 16.10 ± 1.03). Aan die einde van die paartyd (winter) het die manlike blesbokke se spiere ook hoër (p<0.05) CIE a*- en chroma-waardes as die vroulike blesbokspiere (13.49 ± 0.88 en 16.22 ± 0.98) gehad. Die voorkwartspiere het gemiddeld hoër (p<0.05) chroma-waardes as die agterkwartspiere gehad, maar laasgenoemde het weer hoër (p<0.01) hue-angle waardes as die voorkwartspiere gehad. Seisoen het geen effek (p<0.05) op die drupverlies persentasies en taaiheid van die blesbokspiere gehad nie. Die Biceps femoris en Semimembranosus spiere het wel die laagste (p<0.05) drupverlies persentasies gehad. Die Infraspinatus en Supraspinatus spiere het weer die laagste (p<0.01) taaiheid (onderskeidelik 20.89 ± 3.23 en 24.90 ± 5.35) in vergelyking met die Longissimus dorsi, Biceps femoris, Semimembranosus en Semitendinosus spiere gehad (onderskeidelik 30.57 ± 6.69, 27.35 ± 3.42, 28.65 ± 4.48 en 31.51 ± 5.63). Alhoewel daar in die studie statisties beduidende seisoenale verskille in die chemiese samestelling van die blesbokspiere was, is die verskille numeries klein en is dit debatteerbaar of dié verskille enigsins biologies van toepassing is op menslike voeding. Verder het die anatomiese ligging van die geselekteerde blesbokspiere in die studie ʼn groter invloed op die verskille in die vetsuurprofiel, mineraal samestelling asook die fisiese eienskappe van die spiere gehad, in vergelyking met die impak van die oes-seisoen en die effek van geslag.

The effects of dietary ingredients on the proteome profile of postmortem beef longissimus lumborum (LL) muscle were evaluated. In the first experiment, the influence of dietary ractopamine on the whole-muscle proteome of beef LL was examined. Five proteins were differentially abundant between ractopamine-fed (RAC) and non-ractopamine fed (CON) groups. The differentially abundant proteins were over-abundant in RAC and were related to muscle structure development (F-actin-capping protein subunit beta-2 and PDZ and LIM domain protein-3), chaperone (heat shock protein beta-1), oxygen transportation (myoglobin), and glycolysis (L-lactate dehydrogenase A chain). These findings indicated that ractopamine influences the abundance of proteins associated with muscle structure and fiber type shift in beef LL. In the second experiment, the effect of Vitamin E supplementation on the sarcoplasmic proteome of beef LL was characterized. Five differentially abundant proteins were observed between vitamin E-supplemented (VITE) and non-vitamin E-supplemented (CONT) groups. All the differentially proteins were over-abundant in CONT and were associated with antioxidant activity (thioredoxin-dependent peroxide reductase, peroxiredoxin-6, and serum albumin) and glycolysis (beta-enolase and triosephosphate isomerase). These results indicated that the strong antioxidant activity of vitamin E leads to low expression of antioxidant proteins and antioxidant-related glycolytic enzymes in beef LL muscle.

DEVELOPMENT AND VALIDATION OF A LIGHT WEIGHT, ENERGY DENSE, READY TO EAT (RTE) BAR Jacob Wilhelm-Maria Heick Providing additional calories in the form of an RTE bar to endurance athletes will increase performance and muscle re-synthesis, reduce muscle breakdown, and shorten recovery time. An RTE bar containing a blend of dairy proteins and carbohydrates will create a product with superior functionality, including bioactive and immunity enhancing properties from dairy derived ingredients. The protein will provide benefits in the form of easily digestible calories, essential amino acids and physical satiate. A formulation was developed and optimized, resulting in a final product that meets the required nutritional profile: 400kcal, 25grams protein per 100 gram serving size. The desired physical characteristics were achieved through processing by both conventional baking and freeze drying. The latter method improves the stability and functionality of the RTE bar. In order to meet the protein requirements of the RTE bar without compromising sensory properties, a unique protein source was developed. Using high concentrations of conventional protein sources like Whey Protein Concentrate (WPC) resulted in stale off-flavors and unappealing textures. Milk Protein Precipitate (MPP) was developed for this formulation. MPP is a curd-like ingredient created through the combined heat and acid precipitation of dairy proteins. MPP can be used effectively in high concentrations provides a subtle dairy flavor. MPP delivers a balance of casein and whey, similar to that found in milk. The effectiveness of the RTE bar formulation as a post exercise recovery food was evaluated in a human studies experiment conducted on the Cal Poly campus. The human subjects study utilized 34 Cal Poly students in a single-blind cross-over design experiment. The study compared the effects of this high protein RTE bar against a calorically equal carbohydrate bar. The bars were administered after subjects completed the pre-assigned hikes on three consecutive days. Following the cross-over design, subjects received the alternate bar in the second period of the experiment. Several blood markers involved in metabolism and inflammation were measured before and after the two treatment periods. No blood marker showed a statistically significant difference between bars, but several trends were observed. Body weight and fat percent were also unaffected by bar composition.

Food webs in aquatic ecosystems can be dramatically altered by invasive species. Quagga mussels are prevalent invaders that compete with existing species and disrupt nutrient cycling. In 2012, the Quagga Mussel (Dreissena rostriformus bugensis) was introduced into Lake Powell and is expected to move throughout the reservoir in the near future. Stable isotope analysis is a powerful tool for characterizing food webs and trophic interactions. To predict the long-term effects of Quagga Mussels, we used stable isotope analysis of primary producers, primary consumers, prey fish species, and predator fish species in Lake Powell to determine food web structure. Quagga Mussel are positioned to disrupt the pelagic arm of the food web by interfering with the link between phytoplankton and herbivorous zooplankton. This will likely have negative impacts on pelagic fish such as striped bass (Morone saxatilis) and threadfin shad (Dorosoma petenense). Quagga Mussel may also boost benthic productivity in the littoral zone by diverting nutrients from the water column to the benthos. This may have positive impacts on littoral fishes such as largemouth bass (Micropterus salmoides), smallmouth bass (Micropterus dolomieu), bluegill (Lepomis macrochirus), and green sunfish (Lepomis cyanellus).

High pressure (HP) kinetics of the microbial destruction and changes in the physicochemical characteristics of milk and pork were studied. Raw milk samples containing indigenous microflora of approximately 106 CFU/mL were heat sealed in dual peel sterilization pouches and subjected to HP treatment from 150--400 MPa with holding times ranging 5--120 min. The kinetic parameters (rate constant, k and decimal reduction time, D) for the microorganisms, alkaline phosphatase, color and viscosity were evaluated, based on first order kinetics and the pressure dependence of kinetic parameters was evaluated using pressure destruction time (PDT) and Arrhenius models. Kinetic data was well described by the first order model (R 2 > 0.90).
The application of pressure pulse was explored for pressure destruction of microorganisms as well as changes in physical-chemical characteristics of pork chops. Pork chops (2 days post-rigor) were subjected to HP treatment from 200--350 MPa for 0--120 min. Results showed that pressure changes of pork variables followed a dual effect consisting of an instantaneous pressure kill (IPK) with the application of pressure pulse (no holding) and a subsequent first order rate of destruction during the pressure hold time. The IPK values were pressure dependent and increased with pressure level. Parameters k and D indicated a higher rate of pressure destruction of microorganisms compared to quality attributes.
Kinetics of pressure destruction of Listeria monocytogenes Scott A were studied in relation to those of indigenous microorganism of milk and pork. The IPK was more pronounced with L. monocytogenes than with indigenous microflora. However, the kinetic parameters (k and D values) indicated a larger pressure resistance for L. monoctyogenes. HP processes were developed based on the standard plate count (SPC) kinetic data for indigenous microflora of milk as well as L. monocytogenes in milk and pork. The results showed that SPC kinetics permitted good estimation of microbial destruction in low pressure-lethality processes of milk and pork but its application at higher pressure-lethality levels were inaccurate. On the other hand, processes established based an destruction of L. monocytogenes were more predictable. Pressure pulse application to microbial lethality was also well predicted.
The shelf-life of milk and pork increased with the level of applied pressure lethality, but Q10 values suggested that low storage temperature was nevertheless required to control microbial growth and maintain quality. Storage of HP treated park offered some improvement in the texture but resulted in large color changes and drip losses. L. monocytogenes were not detected in any of the stored milk samples HP treated to achieve a lethality ≥10D.

Consumer evaluation, proximate data, Warner-Bratzler shear force (WBSF), fatty acid (FA) composition and volatile compounds were analyzed from the Longissimus thoracis (LT), Tricep brachii (TB) and Gluteus medius (GM) muscles finished on conventional feedlot (FL) and forages, including a perennial legume, birdsfoot trefoil (BFT; Lotus corniculatus), and a grass, meadow brome (Bromus riparius Rehmann, Grass). Representative retail forage (USDA Certified Organic Grass-fed, COGF) and conventional beef (USDA Top Choice, TC) were investigated (n = 6) for LT. Additionally, the effects of diet on Gluteus medius (GM) and Tricep brachii (TB) muscles were explored. Forage-finished beef scored lower (P < 0.05) in most of the affected sensory attributes except BFT which was similar to grain-finished beef. In forage-finished beef GM was more liked and in FL, TB was similar to GM except juiciness where it scored greater. The fat percent was found to be greatest (P < 0.05) in TC followed by BFT and FL. Nutritionally beneficial ratios of FAs were observed in forage-finished diet. Fatty acid concentrations were majorly affected (P ≤ 0.046) by diet. Few long-chain PUFAs were affected (P ≤ 0.015) by muscle type. No FA was a effected (P > 0.05) by the interaction of muscle and diet. 3-hydroxy-2-butanone, known to evoke a buttery sensation was affected (P = 0.011) by diet with greater (P < 0.05) concentration in GM across all diets. Strecker degradation products were affected (P ≤ 0.014) by muscle type being prominent in GM. Meanwhile, 2-ethyl-3,5-dimethyl-pyrazine was greatest (P < 0.05) in BFT. All pyrazine compounds were (P < 0.05) greater in GM. These results indicate that when consumer evaluated beef of finishing diets, FL beef was rated highly. Additionally, not all forages produce similar beef. There were similar ratings for BFT for all attributes except flavor having lower values compared with FL. The chemical composition of BFT beef was found to be intermediary and similar to both FL and Grass beef in many cases. Diet was found to interact with muscle for sensory and chemical measures. The GM and TB of FL did not differ (P < 0.05), while within forage treatments sensory response and chemical composition varied. These results indicate the meat quality of secondary beef muscles is more greatly impacted by forage diets.