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1
Sole, Gisela, e n/a. "Neuromuscular control of thigh and gluteal muscles following hamstring injuries". University of Otago. School of Physiotherapy, 2008. http://adt.otago.ac.nz./public/adt-NZDU20081103.100628.
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Although traditional prevention and management strategies for hamstring injuries have focussed on optimising muscle strength, flexibility and endurance, incidence and/or recurrence rates of these injuries remains high. A theoretical framework was developed considering additional factors that increase the stabilising demand of the hamstrings. These factors included loss of related stability at the knee and lumbopelvic regions and extrinsic factors during functional and sporting activities. The aims of this research were to determine whether electromyographic (EMG) derived hamstrings, quadriceps and gluteal muscle activation patterns as well as isokinetic torque generation patterns could differentiate athletes who had incurred a hamstring injury from uninjured control athletes. It was hypothesised that the EMG activity of the injured participants would be decreased compared to uninjured control participants during maximal activities, but increased during weight bearing activities.
The research included the identification of laboratory-based tasks relevant to the function of the hamstring muscles; test-retest reliability of EMG variables recorded during these tasks; and a comparative cross-sectional study of hamstring-injured (hamstring group, HG) and control athletes (control group, CG). Electromyographic activation patterns were determined during assessment of concentric and eccentric isokinetic strength of the thigh muscles, during transition from double- to single-leg stance, and forward lunging.
Isokinetic and EMG onset and amplitude variables were compared both within- and between-groups. Despite no significant differences for peak torque, the HG injured limb generated lower average eccentric flexor torque towards the outer range of motion in comparison to the HG uninjured limb (P = 0.034) and the CG bilateral average (P = 0.025). Furthermore, the EMG root mean square (RMS) decrease from the start to the end range of the eccentric flexor contraction was greater for the HG injured limb hamstrings than the CG bilateral average.
During the transition from double- to single-leg stance, the EMG onsets of the HG injured limb (biceps femoris [BF] P < 0.001, medial hamstrings [MH] P = 0.001), and the HG uninjured limb (BF P = 0.023, MH P = 0.011) were earlier in comparison to the CG bilateral average. The transition normalised EMG RMS was significantly higher for the HG injured side BF (P = 0.032), MH (P = 0.039) and vastus lateralis (VL, P = 0.037) in comparison to the CG bilateral average. During the forward lunge, no significant differences were observed within- and between-groups for the normalised EMG amplitude prior to and following initial foot contact.
These results suggest that during maximal isokinetic eccentric flexor contractions, the average torque and EMG activity is decreased towards the lengthened position of the hamstring-injured limb. This may be due to structural changes or neurophysiological inhibitory mechanisms. During the static weight bearing task an earlier onset of the HG hamstring muscles was evident in comparison to controls. The hamstrings and the VL of the injured limbs were activated at greater normalised amplitude. The increased muscle activation in the hamstring-injured limbs during the support phase may indicate a greater demand towards stability of the kinetic chain or changes in proprioceptive function. Future research should consider the mechanisms and clinical implications underlying a loss of eccentric flexor torque towards the outer range of contraction, and investigate why increased activation of thigh muscles occurs during the static weight bearing task in hamstring-injured athletes.
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Fernandes, Santos Amanda Aparecida. "The effect of joint angle on surface electromyography amplitude of hamstring muscles". Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/231385/1/Amanda%20Aparecida_Fernandes%20Santos_Thesis.pdf.
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This thesis investigated the effect of knee angle position on the electrical signal of two hamstring muscles using a traditional technique (bipolar electromyography) and a modern technique (high-density electromyography). The results suggest that changes in knee position affect the electrical activity on bipolar electromyography and these changes are associated with the rotation of muscle fibers under the pair of electrodes. However, using high-density electromyography, there was no difference between different knee positions. These findings suggest that high-density electromyography has different responses compared to bipolar electromyography. Hence, studies using bipolar montages need to be interpreted with caution to avoid wrong conclusions.
3
Al-Mousawi, Abdul-Majeed M. "A study of warm-up and injury in hamstring muscles". Thesis, University of Glasgow, 2005. http://theses.gla.ac.uk/6899/.
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This project is the first to investigate blood perfusion in the human hamstrings during isometric exercise with a near infrared spectroscopy (NIRS). A Kin Com dynamometer has been used to fix the knee positions and to measure torques during contractions. Both the NIRS optodes and the electromyography (EMG) electrodes were attached to the skin over the hamstrings. Previous studies used a NIRS to measure muscle blood flow in the forearm, quadriceps and calf muscles. The changes in haemoglobin concentrations were calculated using Spike 2 software. A total of 46 male volunteers participated in the four series of experiments described in this thesis. The following overall conclusions can be drawn: perfusion decreases in the hamstrings during contractions and then returns to normal levels after a period of time, changing the limb position at which the contractions are made does not affect the perfusion, warm-up exercises increase in blood perfusion for 8 minutes at 30 and 40% of MVC. The perfusion did not significantly change during an episode of DOMS or in the injured and non-injured limbs. These conclusions show the importance of warm-up before sports activities but not necessarily avoid injury. It can be concluded that there is no association between such conditions with hamstring injuries. The maintained perfusion at different conditions is a positive finding as the perfusion is not restricted indicating good delivery of oxygen despite muscle injury.
4
Dombroski, Erik. "The influence of cyclic loading on the extensibility of human hamstring muscle-tendon units in vivo a thesis submitted in partial fulfilment for the degree of Master of Health Science, Auckland University of Technology, 2005". Full thesis. Abstract, 2005. http://puka2.aut.ac.nz/ait/theses/DombroskiE.pdf.
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Tafazzoli, Faryaneh. "Mechanical behaviour of hamstring muscles in low-back pain patients and control subjects". Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/9583.
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Baker, Alice Ann. "The Relative Contribution of Flexibility of the Back and Hamstring Muscles in the Performance of the Sit and Reach Component of the AAHPERD Health Related Fitness Test in Girls Thirteen to Fifteen Years of Age". Thesis, North Texas State University, 1985. https://digital.library.unt.edu/ark:/67531/metadc500769/.
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The purpose of the study was to quantify the relative contribution of low back flexibility and hamstring flexibility in the sit and reach test item of the AAHPERD Health Related Fitness Test in order to examine the validity of the sit and reach test. Subjects were 100 female students, 13 to 15 years of age in physical education classes. Hamstring flexibility was measured using the Leighton flexometer. Spinal mobility was measured using a tape measure. The sit and reach test was performed according to instructions given in the AAHPERD Test Manual. Data were analyzed using correlation, linear regression, and multiple regression. Conclusions of the investigation were (1) hamstring flexibility is moderately related to the sit and reach test, (2) low back flexibility has a very small relationship to the sit and reach test, and (3) the sit and reach test is an inadequate measure of low back and hamstring flexibility.
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Jennings, Andrew George. "Neurophysiological changes in muscles around the knee following injury to the anterior cruciate ligament". Thesis, University of Newcastle Upon Tyne, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313269.
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Dobija, Lech. "Effet immédiat de l'étirement des muscles ischio-jambiers chez les patients présentant une lombalgie chronique". Electronic Thesis or Diss., Université Clermont Auvergne (2021-...), 2023. http://www.theses.fr/2023UCFA0127.
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Malgré les progrès réalisés par le système de santé, la lombalgie chronique reste la principale cause d'invalidité. Le déficit d'extensibilité des muscles ischio-jambiers (MIJ), combiné à un déficit de contrôle neuromusculaire, contribue à l'invalidité dans la lombalgie chronique. Dans ce travail, nous décrivons d'abord les mécanismes de la douleur, le modèle biopsychosocial et la biomécanique, en se concentrant sur les déficits d'extensibilité des MIJ. Ensuite, nous estimons les propriétés métrologiques des mesures de l'extension active du genou, Active Knee Extension (AKE), et de la levée de jambe tendue, Straight Leg Raise (SLR) obtenues à l'aide d'un nouvel inclinomètre éléctronique chez les patients souffrant d'une lombalgie chronique. Cette analyse a été effectuée sur les 90 patients inclus dans l'étude EFIM1. La reproductibilité intra-évaluateur pour AKE et SLR s'est révélée excellente, avec un coefficient de corrélation intraclasse, Intraclass Correlation Coefficient (ICC) supérieur à 0,9. Les valeurs de différence minimale détectable, Minimal Detectable Change (MDC95) ont été de 9 à 11° pour AKE et de 7 à 10° pour SLR. Des corrélations modérées à fortes, ont également été trouvées entre AKE, SLR et la distance doigt-sol, Fingertip-to-Floor (FTF), ce qui confirme la validité de construit de nos mesures. L'étape suivante concernait l'évaluation de l'effet immédiat de l'étirement passif des MIJ, ainsi que l'analyse de l'impact des facteurs psychosociaux sur le changement résultant de l'étirement (étude EFIM1). Les mesures répétées de l'extensibilité des MIJ (AKE, SLR, FTF) ont été effectuées sur 90 patients atteints de lombalgie chronique avant et immédiatement après l'intervention. Celle-ci consistait en une minute d'étirement passif des MIJ réalisée de manière bilatérale par un kinésithérapeute. Les facteurs psychosociaux ont été évalués avant l'intervention grâce aux questionnaires Fear-Avoidance Belief Questionnaire (FABQ) et Hospital Anxiety and Depression Scale (HADS). L'extensibilité des MIJ s'est améliorée de manière significative après l'étirement; la différence moyenne de l'AKE était de 4° (IC à 95 % : 2,4 à 5,1° ; p < 0,001), la différence moyenne de la SLR était de 7° (IC à 95 % : 5,5 à 8,6°, p < 0,001), la différence moyenne de FTF était de 2 cm (IC à 95 % : 1,7 à 3,0cm, p < 0,001). Aucune corrélation n'a été trouvée entre l'amélioration d'extensibilité des MIJ et les scores des questionnaires FABQ ou HADS (p > 0,05). L'étirement passif des MIJ a entraîné une amélioration immédiate et statistiquement significative de l'extensibilité des MIJ chez les personnes atteintes de lombalgie chronique. Cependant, seul le changement d'amplitude passive de la SLR semble avoir une importance clinique. Cela suggère que le système neuromusculaire nécessite une stimulation active pour générer un mouvement actif dans l'amplitude de mouvement passive nouvellement acquise. Par conséquent, nous présentons un nouveau protocole d'étude randomisée contrôlée, EFIM2 pour vérifier si la combinaison d'étirements actifs et passifs est plus efficace que l'étirement passif seul pour améliorer la flexibilité active chez les patients souffrant d'une lombalgie chroniqueProgress in healthcare management increased life expectancy globally but disabling consequences of diseases remain the major problem. Despite the progress that has been made in healthcare management, chronic low back pain (CLBP) remains the leading cause of disability. The deficit in hamstring muscles (HM) flexibility, combined with a deficit in neuromuscular control, contributes to disability in CLBP. In this work, we first describe the context that links pain mechanisms, the biopsychosocial model, and biomechanics, with a specific focus on HM flexibility deficits. Then, we estimate the measurement properties of the Active Knee Extension (AKE) and Straight Leg Raise (SLR) measures taken with a new digital inclinometer in CLBP patients. Intrarater reproducibility was found to be acceptable, with a Minimal Detectable Change of 9-11° for AKE and 7-10° for SLR. Following that, we conducted the EFIM1 study to evaluate the immediate effect of passive hamstring (HM) stretching on flexibility and to analyze the impact of psychosocial factors on change following HM stretching in 90 CLBP patients. Hamstrings flexibility improved significantly after stretching; AKE mean difference was 4° (95%CI, 2.4 to 5.1; p<0.001); SLR mean difference was 7° (95%CI, 5.5 to 8.6, p<0.001), Fingertips-to-Floor mean difference was 2 cm (95%CI, 1.7 to 3.0, p<0.001). No correlation was found between improvement in any of the HM flexibility measurements and Fear-Avoidance Belief Questionnaire (FABQ) or Hospital Anxiety and Depression Scale (HADS) scores (p>0.05). Additional group-based analysis showed that the Positive Responders and Non-Responders groups were similar in demographic and clinical characteristics, except for lower Body Mass Index (BMI) values within the Positive Responders group. Passive HM stretching induced an immediate, statistically significant improvement in HM flexibility in people with CLBP. However, only the change in SLR amplitude is likely to be of clinical importance. Psychosocial factors were not related to observed improvements in flexibility. This suggests that the neuromuscular system needs active stimulation to generate active movement in the newly acquired passive range of motion (ROM). Therefore, in response to this conclusion we present a new study protocol, EFIM2. From the patient's perspective, the ultimate goal is to achieve an important improvement in active, pain-free ROM. However, passive stretching did not yield satisfactory improvements in active flexibility. This is why we propose a combination of passive and active stretching exercises, with the expectation that it facilitates improvements in both passive and active ROM. To test our hypothesis that combining active and passive stretching is more effective than passive stretching alone in improving active flexibility, we present a randomized controlled study, EFIM2
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Reynolds, Jonathan F. "A comparative study of the effects of meclofenamate, diclofenac and placebo, in combination with physiotherapy, on the healing of acute quadriceps and hamstring muscle tears". Master's thesis, University of Cape Town, 1991. http://hdl.handle.net/11427/27131.
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A double-blind, placebo controlled research technique was used to determine the effects of two non-steroidal anti-inflammatory drugs, meclofenamate and diclofenac, in combination with physiotherapy treatment, on the rate and extent of healing of acute hamstring muscle tears. Sixty patients were recruited and treated at No's 1 and 2 Military Hospitals in Voortrekkerhoogte and Wynberg, Cape Town, respectively. Patients were randomly allocated to one of three treatment groups: meclofenamate, diclofenac and placebo. Patient assessments were performed on days 1, 3 and 7 of the 7-day study period. These assessments included pain assessment (visual analogue scale), swelling measurement (thigh circumference measurement at the site of the muscle tear) and muscle performance test (Cybex isokinetic dynamometer and data reduction computer). All patients received physiotherapy treatment on all 7 days of the study. This comprised early rest, ice, compression and elevation (RICE), and later, ultrasound and deep transverse friction massage. An intensive regime of strengthening and stretching exercises was used throughout the study, beginning with stretching and isometric exercises gradually moving onto isotonic exercises and aerobic exercise including swimming, running and cycling. No competitive sport was allowed during the study period. Statistical significance was determined using the analysis-of-variance (ANOVA) test with an acceptance level of p<0.05. No differences in pain, swelling or muscle performance were demonstrated between the three treatment groups. In terms of the pain and swelling assessments, the injuries did not appear to be very severe. Accordingly, the groups were divided into severe and non-severe sub-groups and statistical significance was determined using the ANOVA test with an acceptance level of p<0.05. A significant difference was found in the severe hamstring injury sub-group. In this group, pain reduction was greater in the placebo group than in the meclofenamate group on day 7. There were no other significant differences found in this sub-group analysis. Relatively few side effects were encountered, and those encountered were mild. No patients were withdrawn from the study as a result of these adverse events. Drowsiness and gastro-intestinal disturbance were the most common side effects reported. In conclusion, the study found that no benefit was gained from the use of meclofenamate or diclofenac in combination with physiotherapeutic modalities as compared to the use of physiotherapeutic modalities on their own. Thus, the widespread use of NSAIDs in the treatment of acute muscle injuries may not be justified.
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Rösemann, Christel. "The effect of high intensity training on the angle-torque relationship of the quadriceps and hamstring muscles in a group of well-trained cyclists". Master's thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/2993.
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Lord, Cameron. "Lower Limb Fatigue Asymmetry of Preferred and Non-Preferred Legs after a Repeated-Sprint Test in Football Players with Previous Hamstring Injury". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2014. https://ro.ecu.edu.au/theses/1421.
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Football is the most widely played sport in the world and is thus associated with the highest total number of injuries of all sports. 12% of all football injuries are to the hamstrings, as this muscle group is subjected to constant stress during training and match play performance (Ekstrand, Hägglund, Waldén, 2011; Woods, Hawkins, Maltby, Hulse, Thomas & Hodson, 2004). While the influence of limb dominance has been extensively examined as a risk factor for injury in upper limb-dominant sports (e.g. badminton, tennis and baseball), little research has focussed on the dominance in the lower limbs. Since almost all footballers show a limb preference for kicking, an example of limb dominance, it is possible to speculate that limb-specific injury rates will vary between preferred and non-preferred legs (Brophy, Silvers, Gonzales and Mandelbaum, 2010). Previous research has also shown that injury rates increase with the accumulation of fatigue, and that inter-limb force production variation increases as fatigue progresses. Thus, the possibility exists that increases in inter-limb force production variability after fatiguing exercise would increase injury risk in football players. The purpose of the present research, therefore, was to examine changes in muscle force production and fatigue between preferred and non-preferred legs in football players with and without a history of unilateral hamstring injury (in the preferred kicking leg). In the single leg vertical jump, peak jump force of the preferred leg in the injured group changed by -12% whilst force in the non-preferred leg changed by -5%. Force in the non-injured preferred leg changed by -6% and changed by -8% in the non-preferred leg. These results indicate a clear difference in fatigue response between groups, and that the inter-limb difference in force production is greater in the preferred leg of the injured group. Decline in hamstring torque in the preferred leg of the injured group changed by 98%, and the non-preferred leg changed by 67%. While in the non-injured group, decline in hamstring torque changed by 219% and 852% respectively. The greater changes observed in the non-injured group was due to minimal fatigue before the fatigue condition (repeated-sprint test). The injured group had a greater fatigue response both before and after the fatigue condition (26.1±18.4 to 51.7±20.9 N preferred leg and 11.6±8.94 to 19.4±20.5 N non-preferred leg) suggesting previous injury has a different effect on fatigue response. Horizontal force production during the repeated-sprint test changed by -14% in the preferred kicking leg and -3% in the non-preferred leg (injured group). This represents the preferred kicking leg having a greater fatigue response. In conclusion, the present study has provided a foundation for comparing the injured and non-injured group and the preferred and non-preferred kicking legs during a single leg vertical jump, isokinetic endurance test and repeated-sprint test. These tests provided evidence that the non-preferred leg had greater force production, the preferred leg had greater fatigue response, and the inter-limb difference in force production after fatigue was greater in the injured group. It can be assumed that the preferred kicking leg of the injured group being the previously injured leg has attributed to these results. These results highlights the need for future research to further understanding of the differences in preferred and non-preferred kicking legs, why they occur, and the influence they have on injury
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Askling, Carl. "Hamstring muscle strain". Doctoral thesis, Swedish School of Sport and Health Sciences, GIH, Laboratory for Biomechanics and Motor Control, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:gih:diva-425.
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Background: Acute hamstring strains are common injuries in different sports. They are often serious, causing long rehabilitation times and a proneness for re-injury. Preliminary observations indicate that the injuries can be of at least two types, one occurring during high-speed running and the other during motions where the hamstring muscles reach extreme lengths.
Aims: To investigate the possible existence of different types of acute hamstring strains in two specific athletic groups, namely sprinters and dancers, as well as the generality of these findings in other sports.
Methods: In the first project, 18 sprinters and 15 dancers with acute first time hamstring strains were prospectively included. All subjects were examined, clinically and with magnetic resonance imaging (MRI), on 4 occasions after injury: at day 2-4, 10, 21 and 42. The follow-up period was 2 years. In the second project, 30 subjects from 21 different sports were prospectively included. All subjects were examined clinically and with MRI. The follow-up period lasted until the subjects returned to sport or finished their sport activity due to the injury.
Results: All sprinters sustained their injuries during competitive high-speed running. In contrast, all dancers encountered their injuries during slow-speed stretching type of exercises. The initial loss of strength and flexibility was significantly greater in sprinters than in dancers. At 42 days after injury, both groups could perform more than 90% of the test values of the uninjured leg. All the sprinters’ injuries were primarily located in biceps femoris long head, whereas the dancers’ injuries were mainly (87%) involving the proximal free tendon of semimembranosus. For the sprinters, involvement of the proximal free tendon, as estimated by MRI, and proximity to the ischial tuberosity, as estimated both by palpation and MRI, were associated with significantly longer time to return to pre-injury level. In the dancers, there were no significant correlations between clinical or MRI parameters and time to return to per-injury level. The time to pre-injury level was significantly longer (median 50 weeks, range 30-76) for the dancers compared to the sprinters (16, 6-50). In the second project, all injuries occurred during movements reaching a position with combined extensive hip flexion and knee extension. They were all located close to the ischial tuberosity and 83% involved the proximal free tendon of semimembranosus. Fourteen subjects (47%) decided to end their sport activity and for the remaining 16 subjects the median time back to sport was 31 (range 9-104) weeks. There were no significant correlations between clinical and MRI parameters and time to return to sport.
Conclusions: There seems to be a link between the injury situation and the two types of acute hamstring strain in sprinters and dancers with respect to clinical findings, injury location, muscles and tissues involved, and time to return to pre-injury level. Proximity of the injury to the ischial tuberosity, as estimated both by palpation and MRI, is associated with longer recovery time. Also in other sports, an injury situation where the hamstrings reach extensive lengths caused a specific injury to the proximal posterior thigh similar to that described in dancers. Due to the prolonged recovery time associated with this type of injury, correct diagnosis based on history, clinical and MRI investigation, and adequate information to the athletes are essential.
För att beställa tryckta exemplar av avhandlingen kontakta Carl Askling, carl.askling@gih.se
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張劍強 e Kim-keung Cheung. "The effect of hamstring stretching technique on hamstring flexibility and isokinetic strength". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B3125715X.
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Cheung, Kim-keung. "The effect of hamstring stretching technique on hamstring flexibility and isokinetic strength /". Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk:8888/cgi-bin/hkuto%5Ftoc%5Fpdf?B23425374.
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Siegel, Lori L. "Hamstring rehabilitation a systematic review /". Morgantown, W. Va. : [West Virginia University Libraries], 2007. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5158.
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Thesis (M.S.)--West Virginia University, 2007.Title from document title page. Document formatted into pages; contains vi, 98 p. : ill. (some col.). Includes abstract. Includes bibliographical references.
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Sonnekalb, Sara. "Impact of different warm-up conditions on hamstring torque and power". Connect to this title online, 2005. http://www.oregonpdf.org.
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Thesis (M. Ed.)--Bowling Green State University, 2005.Includes bibliographical references (leaves 38-44). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.
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Snyder, Alison Rose. "The acute influence of static and ballistic stretching on the biomechanics and muscle activity associated with the hamstring stretch /". See Full Text at OhioLINK ETD Center (Requires Adobe Acrobat Reader for viewing), 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1102522627.
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Thesis (Ph.D.)--University of Toledo, 2004.Typescript. "A dissertation [submitted] as partial fulfillment of the requirements of the Doctor of Philosophy degree in Exercise Science." Bibliography: leaves 72-77.
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Whyte, Enda. "The influence of reduced hamstring muscle length on patellofemoral joint kinematics". Thesis, University of Strathclyde, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.502313.
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Edupuganti, Pradeep. "Effect of resistance training in the improvement of hamstrings to quadriceps (H:Q) strength ratio in males and females". To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2008. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Muller, Brusco Clarissa. "Hamstring muscle architecture parameters in static and dynamic conditions using ultrasound imaging". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2022. https://ro.ecu.edu.au/theses/2571.
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Biceps femoris long head (BFlh) fascicle length (Lf), fascicle angle (FA), and muscle thickness (MT) were assessed at rest and during dynamic contractions using B-mode ultrasound imaging. The assessments were performed in men and women with no previous hamstring strain injury. Volunteers visited the laboratory for two separate data collection sessions (Day 1 and Day 2) relating to two independent projects, seven days apart at the same time of day for test-retest measurements of the static assessments. For the dynamic assessments, familiarization with the isokinetic concentric and eccentric knee flexion exercises were performed on Day 1. On Day 2, BFlh Lf, FA and MT were assessed in real time using two serially aligned ultrasound devices whilst performing consecutive concentric and eccentric knee flexions at 30°/s and 180°/s.
To acquire images at rest, ultrasound imaging was performed using extended field-of-view (EFOV) and static image acquisition sequences of four single images acquired in-series along the muscle. From these images, Lf was assessed using seven methods: EFOV, Collage, manual linear extrapolation, and using four different trigonometric equations, and then FA and MT were measured in EFOV, Collage, and Single images. Lf, FA and MT measured on Days 1 and 2 were not different (p > 0.05) for any method, reliabilities were very high (ICC: 0.91-0.98), and correlations were strong ( ≥ 0.84). Significant correlations (p < 0.05; r=0.67-0.98) were found between EFOV and the other measurement techniques for Lf, FA and MT. The Collage method had the highest reliability for Lf, and highest rank order and correlation with EFOV. The Collage method can therefore be recommended for use if the methodology presented herein is followed.
For assessments during dynamic contractions, participants performed consecutive concentric and eccentric contractions at 30°/s and 180°/s whilst in vivo muscle function was recorded using two in-series transducers. At 30°/s both submaximal (55% maximum) and maximal contractions were performed whilst at 180°/s only maximal contractions were performed both before and after fatiguing exercise. Ultrasound videos were exported and edited to create a single, synchronized video and three fascicles were analyzed through the range of motion. Changes during concentric and eccentric contractions (Δ) in Lf, FA and MT at short (60-90° knee angle; 0° full knee extension) and long (0-30°) muscle lengths and across the full knee flexion range were measured and compared. Comparisons were made within exercises performed with the same contraction velocity. When fascicle behaviors were compared during submaximal and maximal concentric and eccentric contractions at 30°/s, greater ΔLf was observed at longer muscle length during both eccentric and concentric contractions (p=0.01), and this alteration was greater during eccentric contractions (p=0.02) at longer muscle lengths (p < 0.001). Greater ΔFA was observed at long length during eccentric contractions (p=0.02). When whole range of motion was analyzed, greater ΔMT was observed (p=0.03) in concentric contractions. When fascicle behavior was compared in the maximal contractions at 180°/s before and after fatiguing exercise, greater ΔLf was observed in the eccentric contraction at the long muscle length (p = 0.01), ΔFA was greater at short muscle lengths in the concentric contractions (p=0.02) and at long muscle lengths (p=0.006) and at full range of motion (p=0.006) during eccentric contractions. Less ΔFA was detected across all contractions (p < 0.05) after the fatiguing exercise when measured through the full range of motion. Greater dynamic torque was observed at long muscle lengths, during eccentric contraction, and before the fatiguing exercise (p < 0.05).
Although the six different techniques used to estimate Lf during rest provided values similar to EFOV, the Collage sonographic method provided the most accurate and reliable results and is therefore recommended for BFlh architectural analysis when EFOV is not available. Greater ΔLf and ΔFA were observed for a given joint rotation increment during submaximal and maximal eccentric contractions at long muscle lengths. The increased fascicle strain at long muscle length might contribute to both increased metabolic stress, and therefore longer-term muscle hypertrophy, and to muscle strain injuries.
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Evangelidis, Pavlos. "Hamstrings muscle anatomy and function, and implications for strain injury". Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/18033.
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The main aim of this thesis was to examine hamstrings anatomy and its influence on knee flexor muscle function in healthy young men. A secondary aim was to better understand the implications of hamstrings anatomy and function, and their variability, in relation to the risk of strain injury. The functional and conventional H:Q ratios (examined up to high angular velocities) as well as the knee joint angle-specific isometric H:Q ratio exhibited good test-retest reliability at joint positions that closely replicated the conditions of high injury risk. Football players did not exhibit any differences in angle-specific or peak torque H:Q ratios compared to recreationally active controls. Knee extensor and flexor strength, relative to body mass, of footballers and controls was similar for all velocities, except concentric knee flexor strength at 400° s-1 (footballers +40%; P < 0.01). Muscle volume explained 30-71% and 38-58% of the differences between individuals in knee extensors and flexors torque respectively across a range of velocities. A moderate correlation was also found between the volume of these antagonistic muscle groups (R2= 0.41). The relative volume of the knee extensors and flexors explained ~20% of the variance in the isometric H:Q ratio and ~31% in the high velocity functional H:Q ratio. Biceps femoris long head exhibited a balanced myosin heavy chain isoform distribution (47.1% type I and 52.9 % total type II) in young healthy men, while BFlh muscle composition was not related to any measure of knee flexor maximal or explosive strength. Biceps femoris long head proximal aponeurosis area varied considerably between participants (>4-fold) and was not related to biceps femoris long head maximal anatomical cross-sectional area (r= 0.04, P= 0.83). Consequently, the aponeurosis:muscle area ratio exhibited 6-fold variability (range, 0.53 to 3.09; CV= 32.5%). Aponeurosis size was not related to isometric or eccentric knee flexion strength. The findings of this thesis suggest that the main anatomical factor that contributes to knee flexors function in vivo is hamstrings muscle size, while muscle composition and aponeurosis size do not seem to have a significant influence. The high inter-individual variability of the biceps femoris long head proximal aponeurosis size suggests that a disproportionately small aponeurosis may be a risk factor for strain injury. In contrast, biceps femoris long head muscle composition does not seem to explain the high incidence of strain injuries in this muscle. Quadriceps and hamstrings muscle size imbalances contribute to functional imbalances that may predispose to strain injury and correction of any size imbalance may be a useful injury prevention tool. Finally, regular exposure to football training and match-play does not seem to influence the balance of muscle strength around the knee joint.
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Bourne, Matthew N. "Hamstring strain injury: The role of strength and voluntary activation". Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/98262/4/Matthew_Bourne_Thesis.pdf.
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Hamstring strain injuries are endemic in running-based sports, often resulting in substantial performance decrements and costing professional sporting organisations millions of dollars each year. This program of research has contributed new knowledge relating to factors which may predispose to, and manifest as a result of hamstring injury, while also providing novel data which may be used to inform injury prevention and rehabilitation practices.
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Yelizarov, Nikolay. "The effect of electrical intramuscular stimulation on sub acute and chronic hamstring muscle strain injuries". Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/202.
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Muscle strain injuries affect a wide range of physically active people around the world and are reaching epidemic proportions. Despite the variety of treatment options available in rehabilitation, there are no clear guidelines for electrical stimulation that provide effective reproducible results that address the underlying cause of these injuries. For instance, electrotherapy is inefficient at stimulating muscles, because of imprecise parameters and an ability to target particular muscles. The difference between this study and previous research is the precise delivery of electrical stimulation (intramuscular) at two different frequencies (2 Hz and 50 Hz) and comparing it a control group.
Objective: To determine the difference on muscle strength and functional status between three treatments modalities for sub acute and chronic hamstring strains.
Design: A randomized experimental design was used to compare the effects of low (2 Hz), high (50 Hz) and no-electrical (control) intramuscular stimulation on muscle strength and mental and functional status (AMSMC HEALTH STATUS INDEX). Each group consisted of 18 subjects.
Main Outcome: The difference in treatment modalities was evaluated by comparing the muscle strength test (Biodex Dynamometer) results and the AMSMC HEALTH STATUS INDEX results in pretest and post-test conditions.
Results: The AMSMC HEALTH STATUS INDEX, but not muscle strength test (Biodex), changed significantly after 2-Hz electrical intramuscular stimulation (pre-test µ = 66.56, Std= 11.92, post-test µ= 92.89, Std= 6.25), whereas no statistically significant changes in health status index and muscle strength test occurred with 50-Hz (pre-test = 69.22, Std= 11.31, post-test µ= 70.22, Std= 12.27)) and no-electrical stimulation groups (pre-test µ= 69.11, post-test µ= 73.39, Std= 13.18).
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Smink, Kyle Andrew. "The effects of hamstring delayed onset muscle soreness on functional knee joint stability". [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0001500.
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Maniar, Nirav. "Muscle force contributions to knee joint loading". Thesis, Australian Catholic University, 2017. https://acuresearchbank.acu.edu.au/download/9092bf05e33ece328cba05aae3620898d48c8720b4140530a2b8df8e1bb03e24/6002615/MANIAR_2017_Muscle_force_contributions_to_knee_joint.pdf.
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Anterior cruciate ligament (ACL) injuries are one of the most common knee injuries suffered by athletic populations. ACL injuries are particularly burdensome due to potential surgical requirements, extensive rehabilitation time and associated financial costs for the individual and the community. Additionally, ACL injuries are associated with increased risk of early onset knee osteoarthritis. As such, ACL injury preventative and rehabilitative strategies are of paramount importance.
ACL injuries typically occur during non-contact dynamic tasks, such as unanticipated sidestep cutting. At the time of injury, the knee joint experiences relatively large degrees of knee valgus and rotation (either internal or external) and high mechanical loads. These loading patterns, along with the anterior shear force, are known to increase loads on the ACL, especially in combination with each other. Muscles produce forces that can cause and oppose these knee joint loads, and therefore play a critical role in dictating the size and the nature of the loads experienced by the ACL. Prior research has investigated the role of muscle force in ACL load development, and has indicated that the hamstrings are most capable of reducing ACL loads. Subsequently, any pathology that may influence hamstring function may increase the risk of ACL injury.
Some studies have shown that participants with a history of hamstring strain injury (HSI) have lower knee flexor strength and hamstring muscle activation compared to healthy legs. Consequently, a relationship between prior HSI and ACL injury could exist. However, establishing this relationship is difficult due to the relatively low incidence of ACL injury. Subsequently, prospective studies aiming to investigate this relationship would be very costly, due to the requirement of very large sample sizes and long follow-up periods. Additionally, such a relationship would depend on the functional role of the hamstring muscle group during potentially ACL-injurious manoeuvres such as sidestep cutting, which has not been fully elucidated. Furthermore, given the multi-planar demands of tasks that place the ACL at risk of injury, better understanding the contribution of the individual hamstring muscles to knee joint loading relative to the other lower-limb muscles is imperative.
Musculoskeletal simulation offers the ability to analyse cause-effect relationships between muscle force development and joint loading whilst accounting for whole body kinematics. This analysis could not only reveal the true potential of the hamstring muscles in protecting the ACL, but could also elucidate the role of other muscles which have been less studied.
The purpose of this doctoral thesis was to explore the relationship between muscle forces in the development of knee joint loading during potentially injurious manoeuvres, as this knowledge may be used to inform interventions that aim to reduce ACL injury risk. Given recent hypotheses suggesting a possible association between prior injury to the hamstrings and an increased risk of ACL injury and based on the current literature, which indicates that the hamstrings are one of the most important muscle groups for unloading the ACL, the focus of the first study (Chapter 4) was to determine the impact of HSI on hamstring function. Specifically, a systematic review and meta-analysis was used to compare knee flexor strength and flexibility in previously injured legs to the uninjured contralateral leg. It was found that deficits in concentric and eccentric strength (and associated hamstring to quadriceps strength ratios) were present at and after return to play. Isometric strength deficits were also present after HSI, but these recovered within 20-30 days. Hamstring flexibility deficits were also found after HSI, but these recovered within 40-50 days post injury. A secondary aim of this study was to document the totality of measures reported in the literature that have been taken in previously injured hamstrings. The review revealed that knee flexor and extensor strength were the most commonly assessed variables in participants with previously injured hamstrings and that there are few studies which examine the function of other lower-limb muscles. Furthermore, there was limited information examining multi-planar movements. The findings of the review highlighted the need to better understand how the hamstrings contribute to knee joint loading, relative to the contribution of other lower-limb muscles, to better guide future work examining the link between prior HSI and future ACL injury.
The conclusions obtained from Chapter 4 informed the direction of the three subsequent chapters. The focus of the second study (Chapter 5) was to investigate the contribution of the hamstrings to ACL loading during the weight acceptance phase of an unanticipated sidestep cut relative to other lower-limb muscles. A musculoskeletal modelling approach was used to determine how different lower-limb muscles contribute to the key markers of ACL loading, namely the anteroposterior tibiofemoral shear force, and the valgus and rotation reaction moments. It was found that the hamstrings and gluteal muscles play a dominant role in protecting the ACL, by opposing the anterior shear force and valgus reaction moment, respectively. These same muscle groups were found to oppose each other in the transverse plane, thus limiting knee rotation loading.
The focus of the third study (Chapter 6) was to determine the contribution of the hamstrings to the medial and lateral tibiofemoral compartment contact force during unanticipated sidestep cutting relative to other lower-limb muscles. This was because ACL injuries rarely occur in isolation, and are associated with long-term degeneration of articular knee cartilage. A custom musculoskeletal model was created with a modified knee joint mechanism, which permitted the computation of tibiofemoral compartment contact forces via a dynamic equilibrium approach. It was found that medial tibiofemoral contact loading was primarily produced by the vasti, gluteus medius and gluteus maximus and the medial gastrocnemius, whilst lateral tibiofemoral loading was produced primarily by the vasti, soleus, and the medial and lateral gastrocnemius. The medial hamstrings tended to load both compartments, whilst the biceps femoris long head loaded the lateral compartment and induced a relatively small decompression impulse in the medial compartment. Additionally, it was found that most muscles tended to compress both compartments, whilst other muscles had the ability to compress one compartment and decompress the other.
The focus of the fourth study (Chapter 7) was to determine how the hamstrings contribute to coordinating the stance phase of an unanticipated sidestep cut. A musculoskeletal modelling approach was used to estimate lower-limb muscle forces, and a ground reaction force (GRF) decomposition method was used to determine how muscles contributed to the GRFs. It was found that bodyweight support is primarily modulated by the vasti, gluteus maximus, soleus, and gastrocnemius. These same muscles, along with the hamstrings, were also the primary modulators of anteroposterior progression. By contributing to the medial GRF, the vasti, gluteus maximus and gluteus medius were primarily responsible for redirecting the centre-of-mass toward the cutting direction.
This program of research has identified the contribution of the hamstrings, as well as other lower-limb muscles, to knee joint loading and performance during a change-of-direction task. The first study synthesised the retrospective evidence base investigating hamstring strength and flexibility in participants with a history of HSI. This study also identified that assessments of function post HSI tend to focus mostly on the hamstrings during isolated strength assessments, neglecting other lower-limbs muscles. This highlighted the need to better understand the hamstrings role in potentially ACL injurious tasks, relative to other lower-limb muscles. In these investigations the hamstrings were found to be an important muscle group to oppose anterior shear forces during unanticipated sidestep cutting, whilst other non-knee-spanning muscles were found to have a substantial role in developing and opposing other surrogate markers of ACL loading. Similarly, both knee-spanning and non-knee-spanning muscles were found to play a substantial role in compressive loading of the medial and lateral tibiofemoral compartments. Additionally this program of research developed a greater understanding of the contribution of the hamstrings, and other lower-limb muscles, to the coordination of a sidestep cut. The hamstrings played a key role in maintaining anterior propulsion during early stance, although the majority of the demands of sidestep cutting (bodyweight support, propulsion and redirection) were provided by the vasti, gluteus maximus, soleus and gastrocnemius.
The data from this program of research will inform ACL injury rehabilitation and injury prevention practices which should consider not only targeting the hamstrings but also other non-knee-spanning muscles for loading and unloading the knee during sidestep cutting. Additionally, this thesis provides data that may inform strategies aiming to modulate muscle forces to alter tibiofemoral compressive forces, which may be involved in ACL injury and concomitant meniscal and articular cartilage injury. Finally, this thesis provides further data informing how these muscles contribute to the performance of sidestep cut, in order to achieve optimal balance between performance and injury risk considerations. The findings from this thesis also dictates that future investigations that aim to examine the link between prior HSI and increased knee joint loading need to broaden the scope of such work to consider the influence of other lower-limb muscles as well as multi-planar movements.
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Willhoit, Kristin Florence. "Effect of ankle position on hamstring strength during maximum and submaximum leg curls". [Pensacola, Fla.] : University of West Florida, 2007. http://purl.fcla.edu/fcla/etd/WFE0000048.
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Voukelatos, Dimitrios. "Mathematical description of in-vivo muscle function". Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/21772.
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Mathematical relationships have long been used to describe many aspects of muscle function such as the relationship between muscle force and muscle length, muscle force and velocity of contraction or the degree of muscle activation during a contraction. During this work various mathematical expressions have been employed in order to gain an insight into different aspects of muscle activity. The first part of the work examined whether performing a strength protocol on a dynamometer can lead to an increase in eccentric strength output as well as in the neuromuscular activation of the quadriceps group of muscles that appears inhibited during slow concentric and fast eccentric contractions. Neuromuscular activation was modelled via a three-parameter sigmoid function that was also tested for robustness to perturbations in the maximum activation values. During the second part of the study the "functional" hamstrings to quadriceps ratio H:Qfun was expressed as a function of two variables i.e., angular velocity and joint angle. Initially nine-parameter torque-angular velocity-angle profiles were obtained for the knee extensors and flexors from a group of participants. A theoretical 17- parameter H:Qfun function was then derived for each dataset. Subsequently, a simpler, 6-parameter function was derived, RE = aexp(bωn + cθm)-dω1/2θ2 that best reproduced the original 17-parameter fit. Finally, a six-segment subject specific torque-driven model of the Snatch lift was developed in order to investigate the optimal mechanics of the lift. The model simulated the lift from its initiation until the end of the second pull when the feet of the athlete momentarily leave the platform. The six-segment model comprised of foot, shank, thigh, torso (head + trunk), arm and forearm segments with torque generators at the ankle, knee, hip and shoulder joints respectively. The torque profiles were obtained using an isokinetic dynamometer.
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Freeman, Brock. "The role of sprint training in hamstring strain injury prevention for field sport athletes". Thesis, Federation University Australia, 2022. http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/185191.
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Hamstring strain injuries (HSI) are regularly reported as the most common injury in many field-based sports with a high-speed running (HSR) component. Typically, these injuries occur during sprinting efforts, predominantly in the Biceps Femoris Long Head (BFLH). Furthermore, the burden of HSI is amongst the highest in field sports, and the risk of recurrent injury is elevated, and inflated by age. It is of interest to managers, technical coaches, physical preparation staff and athletes to reduce the risk of sustaining a HSI. Therefore, extensive research in HSI has identified several non-modifiable and modifiable risk factors, such as eccentric hamstring strength, BFLH fascicle length, and HSR exposure. Currently, almost all interventions designed to reduce the risk of HSI have utilised resistance training or stretching interventions. This is despite the scientific literature indicating that; 1) sprinting is the most common mechanism associated with hamstring strain injury, and 2) sprinting places a far greater demand on the hamstrings than interventions that are resistance or flexibility based. Therefore, the primary aim of this thesis was to establish the role of sprint training in HSI prevention in field sport athletes. The aim of Study 1 was to understand the beliefs and practices of professional Australian Football (AF) physical performance coaches towards the training and assessment prescribed to mitigate the risk of HSI. A Delphi-validated mixed methods survey was implemented to assess the beliefs and practices of High-Performance Managers of professional AF teams. All the participants in this study reported that they believed sprinting (acceleration and maximum speed) was the most common activity associated with HSI. Similarly, all participants also indicated they performed sprint training for injury prevention purposes. However, a range of relative speeds were reported to quantify HSR, whilst a sprint was reported as 85%Vmax. Whilst respondents reported they believed that sprint training was important, one participant indicated that they felt the need to be conservative with the prescription of sprint training for fear of injury, and the consequences associated with this. Due to the identified discrepancies in speed thresholds used in practical setting (Study 1) and academic settings (Literature Review), Study 2 was designed to determine the absolute, and relative speeds associated with jogging, running, striding, near maximum sprinting, and sprinting. The secondary aim was to visually describe the gait patterns associated with HSR and sprinting. Fifteen participants completed two data collection periods, where they performed a series of run throughs at different gait patterns. These gait patterns were adapted from a review of time-motion research in field sports. The running gaits of jogging, running, striding, near-maximum sprinting, and sprinting correspond with the relative speeds of 56%Vmax, 66%Vmax, 78%Vmax, 87%Vmax, and 100%Vmax, respectively. Significant (p = 0.01) differences were observed for all variables between striding, near-maximum sprinting, and sprinting. This highlights that previously reported thresholds in Study 1 are likely not quantifying the true sprinting demands. Publicly available injury information indicates a spike in HSI during the 2018 Australian Football League (AFL) season, a trend that occurred in the relatively uninterrupted 2020 AFL season. As Study 2 indicated that thresholds used to quantify the demands of sprinting in training and competition, Study 3 primarily aimed to determine the amount of running completed in relative speed bands during the pre-season and then the first eight weeks of the season. The secondary aim was to determine how individual athletes vary from the group average across the pre-season and the first eight rounds of the season. This study completed a retrospective analysis of 55 professional Australian footballers during the pre-season and first eight rounds of the 2019 season. Significantly less (p < 0.05) weekly volume was reported during the first 8 weeks of the season in the speed thresholds of 71-80%Vmax, 81-90%Vmax, and 91-100%Vmax. However, athletes in this study only completed an average of 18m above 90%Vmax in the pre-season, a stimulus too low to achieve an injury prevention and conditioning effect. Individual analysis highlighted that whilst a small number of athletes achieved a consistent sprinting load, several athletes did not achieve more than 2m above 90%Vmax during both the pre and in-season periods. This lack of preparation may provide a rationale for the injury rates during the first eight rounds. To improve the preparation of athletes using a sprinting stimulus, Study 4 focussed on addressing modifiable risk factors for HSI. The primary aim of this study examined the effects of acceleration and maximum speed sprint training of eccentric hamstring strength, BFLH fascicle length, and sprint performance. Initially, a training study with 60 participants was planned, but due to the Victorian Government’s COVID-19 restrictions, this was modified to a case study design with 11 participants. A 6-week training intervention consisting of acceleration sprinting (<15m) or maximum speed sprinting with a gradual build up (flying 10-20m) was implemented. Participants that performed acceleration or maximum speed sprinting improved Biceps Femoris fascicle length by 23% and 20%, respectively. This was an increase of more than the Minimum Detectable Change (MDC95 = 0.96cm, 95% CI =0.93 – 0.99cm). The participants who completed normal training experienced no change in the BFLH fascicle length. Neither sprint training intervention produced a change in eccentric hamstring strength that was greater than the typical error in the test. Both sprinting interventions improved sprint performance outcomes, however both acceleration and maximum speed training produced a larger improvement in maximum speed (-11% and -9%, respectively) than in acceleration qualities (-2% and -3%, respectively). Both acceleration and maximum speed training incurred positive improvement in relative force production (F(0) (N/kg)) and relative power production (Pmax (W/kg)). This was similar for DRF and RFpeak and indicates that sprint training without resistance will improve Force-Velocity-Power Variables. This project has provided new information regarding the role of sprint training for hamstring strain injury prevention. Firstly, both 6 weeks of low volume acceleration and maximum speed sprinting improve BFLH fascicle length. Secondly, currently employed velocity thresholds in professional AF are likely too slow to quantify the HSR and sprinting demands. Thirdly, analysis using thresholds that are faster than previously reported revealed that the overall volume of sprinting (>90%Vmax) is too low to elicit an injury prevention or training stimulus. This information will inform the future practices of key stakeholders surrounding sprint training in field sport athletes. The identification of the positive benefits of maximum speed sprinting, and a faster, more accurate definition of sprinting has large potential to improve hamstring strain injury prevention and increase physical performance.Doctor of Philosophy
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Law, Roberta Yu Wai. "Effects of a three-week hamstrings stretch program on muscle extensibility and stretch tolerance in patients with chronic musculoskeletal pain". Thesis, The University of Sydney, 2009. http://hdl.handle.net/2123/5420.
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Background: Physical deconditioning is often associated with chronic pain and is believed to be a result of gradual movement inhibition and reduction of physical activities. It is common for chronic pain sufferers to present with limited muscle extensibility and poor tolerance to physical movement. Exercises are therefore prescribed to assist in regaining muscle extensibility, strength, fitness and endurance. Of particular interest is stretch, a type of exercise aimed at increasing muscle extensibility. Stretch is commonly prescribed as part of physical rehabilitation in pain management programs, yet little is known of its effectiveness in the chronic pain population. Aim: The aim of this randomised controlled trial was to investigate the effects of a three-week stretch program on muscle extensibility and stretch tolerance in patients with chronic musculoskeletal pain. Methods: Thirty adults with pain persisting for at least three months and limited hamstring muscle extensibility were recruited from patients enrolled in a multidisciplinary pain management program at a Sydney Hospital. A within-subject design was used, with one leg of each participant randomly allocated to an experimental (stretch) condition and the other to a control (no stretch) condition. The hamstring muscles of the experimental leg were stretched for one minute a day over a three-week period, whilst the hamstring muscles of the control leg were not stretched during this time. This intervention was embedded within a pain management program and supervised by physiotherapists. Primary outcome measures were muscle extensibility and stretch tolerance, reflected by passive hip flexion angles produced with standardised and non-standardised torques, respectively. Initial measures were taken prior to the first stretch on day one and final measures were taken one to two days after the last stretch. A blinded assessor was used for all testing. Results: After three weeks of intervention, stretch did not increase muscle extensibility (mean between-group difference in hip flexion was 1 degree; 95% CI -2 to 4 degrees) but did improve stretch tolerance (mean between-group difference in hip flexion was 8 degrees; 95% CI 5 to 10 degrees). Conclusion: Three weeks of stretch increases tolerance to the discomfort associated with stretch but does not change muscle extensibility in patients with chronic musculoskeletal pain. This study provides support for the ongoing incorporation of stretch in pain management programs, where stretch may be conceptualised as a graded exposure to movement and assisting in the restoration of normal activity and function.
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Law, Roberta Yu Wai. "Effects of a three-week hamstrings stretch program on muscle extensibility and stretch tolerance in patients with chronic musculoskeletal pain". University of Sydney, 2009. http://hdl.handle.net/2123/5420.
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Master of Philosophy (MPhil)Background: Physical deconditioning is often associated with chronic pain and is believed to be a result of gradual movement inhibition and reduction of physical activities. It is common for chronic pain sufferers to present with limited muscle extensibility and poor tolerance to physical movement. Exercises are therefore prescribed to assist in regaining muscle extensibility, strength, fitness and endurance. Of particular interest is stretch, a type of exercise aimed at increasing muscle extensibility. Stretch is commonly prescribed as part of physical rehabilitation in pain management programs, yet little is known of its effectiveness in the chronic pain population. Aim: The aim of this randomised controlled trial was to investigate the effects of a three-week stretch program on muscle extensibility and stretch tolerance in patients with chronic musculoskeletal pain. Methods: Thirty adults with pain persisting for at least three months and limited hamstring muscle extensibility were recruited from patients enrolled in a multidisciplinary pain management program at a Sydney Hospital. A within-subject design was used, with one leg of each participant randomly allocated to an experimental (stretch) condition and the other to a control (no stretch) condition. The hamstring muscles of the experimental leg were stretched for one minute a day over a three-week period, whilst the hamstring muscles of the control leg were not stretched during this time. This intervention was embedded within a pain management program and supervised by physiotherapists. Primary outcome measures were muscle extensibility and stretch tolerance, reflected by passive hip flexion angles produced with standardised and non-standardised torques, respectively. Initial measures were taken prior to the first stretch on day one and final measures were taken one to two days after the last stretch. A blinded assessor was used for all testing. Results: After three weeks of intervention, stretch did not increase muscle extensibility (mean between-group difference in hip flexion was 1 degree; 95% CI -2 to 4 degrees) but did improve stretch tolerance (mean between-group difference in hip flexion was 8 degrees; 95% CI 5 to 10 degrees). Conclusion: Three weeks of stretch increases tolerance to the discomfort associated with stretch but does not change muscle extensibility in patients with chronic musculoskeletal pain. This study provides support for the ongoing incorporation of stretch in pain management programs, where stretch may be conceptualised as a graded exposure to movement and assisting in the restoration of normal activity and function.
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Barreira, P. A. "The role of acceleration related variables for hamstring muscle (re-) injury prevention in elite association football". Thesis, Liverpool John Moores University, 2017. http://researchonline.ljmu.ac.uk/5761/.
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Hamstring muscle injuries constitute a major concern in football and a major challenge for physiotherapists working in this sport, being an injury with long absence from playing and training. Although clinical strategies to rehabilitate these injuries and clinical injury risk assessments have been explored over the years, a broader comprehension of how variables regarding running performance may in some form relate to hamstring injury risk has been missing for clinical professionals. Together with this, its incidence has been increasing despite many preventive efforts, which reveals a necessity for developing risk assessment methods to better inform preventive strategies. The key involvement of hamstring muscles during accelerations and decelerations during football running actions justifies research into acceleration related observations. Therefore, the aims of the current programme of research were to develop new laboratorial and load monitoring strategies related to acceleration actions, by exploring biomechanical factors from a physiotherapist perspective. Additionally, implementing assessments and exposing some key limitations of these assessments in professional clubs is also described throughout the experimental studies of this thesis (chapters 3 and 5). For the purposes of this thesis, force development variables were analysed in chapter 3, during maximal accelerations on a non-motorised treadmill, and comparisons between professional players with and without previous injuries were performed. Results from this study revealed no differences between groups during both maximal acceleration and steady state of a maximal sprint effort. A second approach regarding risk analysis and acceleration variables considered the mechanical load based on trunk-mounted accelerometry used in outfield training, as detailed in chapter 5 of the present thesis. In this study mechanical load expressed by PlayerLoadTM, an accelerometer-derived variable aimed to express the rate of change in acceleration, was collected for the training sessions during three weeks previous to a hamstring injury event, in English Premier League clubs, using matched healthy controls. Although the results did not show significant differences between experimental and control group, this exploratory method may constitute a promising method to assess hamstring injury risk. Reliability and validity of the acceleration related variables were addressed first for each of the two experimental studies detailed in chapter 3 and 5. For this purpose, a pilot study on reliability of force collection using a non-motorised treadmill was performed to test the experimental protocol with results showing good overall reliability. For the PlayerLoadTM, a laboratorial study detailed in chapter 4 using a laboratorial overground soccer simulation protocol was adopted and convergent validity with subjects´ anthropometrics together with reliability analysis of four isolated football actions (jogging, side cut, stride and sprint) was performed. Results of this study revealed no association between PlayerLoadTM and the subjects height or body mass and also an overall good reliability for the four actions analysed. In summary, the research presented in this thesis helped better understand the current value and limitations of screening and monitoring acceleration related variables in the context of hamstring (re-)injury prevention in professional football, introducing to the clinical field a different perspective of addressing hamstring behaviour during acceleration actions, and its hypothetical relation with hamstring injury.
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Langford, Nancy Jane. "The Relationship of the Sit and Reach Test to Criterion Measures of Hamstring and Back Flexibility in Adult Males and Females". Thesis, North Texas State University, 1987. https://digital.library.unt.edu/ark:/67531/metadc501137/.
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The purpose of this study was to examine the criterion-related validity of the sit and reach test as a measure of hamstring and low back flexibility in adult males and females. Subjects were 52 males and 52 females, 20 to 45 years of age. Hamstring flexibility was measured using a goniometer. Spinal flexibility was measured using a tape measure and an inclinometer. The sit and reach test was performed according to the AAHPERD Health Related Fitness Test Manual. Data were analyzed using correlations and appropriate descriptive statistics. Conclusions of the investigation were: 1) in adult males 20 to 45, the sit and reach test is a valid measure of hamstring flexibility but has questionable validity as a measure of low back flexibility, 2) in adult females 20 to 45, the sit and reach test is a moderately valid measure of hamstring flexibility and is not a valid measure of low back flexibility.
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Svensson, Felicia. "The loaded barbell squat: Muscle activation with the barbell in a free compared to a fixed vertical movement path in healthy athletes". Thesis, Umeå universitet, Avdelningen för fysioterapi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-175878.
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Introduction: Loaded barbell squat is one of the most popular exercises among athletes and can be performed in many different ways to achieve different goals. The difference in muscle activation between a free and afixed vertical movement path (using Smith machine) has not been examined to a particularly large extent. Aim: To investigate differences in muscle activation of the gluteal and thigh muscles when performing the loaded barbell squat in a free movement path compared to a fixed vertical movement path in healthy athletes under standardized conditions. Methods: Repeated measures within-subjects design were used. Five squats per condition was performed with a weight representing 100% of the participants bodyweight at a tempo of four seconds per repetition. Muscle activation was measured with the EMG-shorts MBody3. Both conditions tested on the same day and the participants was randomized to what condition to start with. Results: No difference was observed between the conditions for the mean value of muscle activation the whole squat. Mm. quadriceps and mm. hamstrings showed significantly higher muscle activation at the end of the eccentric and the beginning of the concentric phase of the squat when the squat is performed with the barbell in a free movement path. For m. gluteus maximus no difference was observed, neither in the whole squat nor in any parts of the squat. Conclusion: This study provides preliminary evidence that mm. quadriceps and mm. hamstrings muscle group show lower muscle activation in parts of the squat when performed in a Smith machine. No significant difference was observed considering the whole movement.Introduktion: Knäböj med skivstång är en av de mest populära övningarna bland idrottare och kan utföras på många olika sätt för att uppnå olika mål. Skillnaden i muskelaktivering mellan fri och fixerad vertikal rörelsebana (med Smithmaskin) har inte undersökts i särskilt stor omfattning. Syfte: Att undersöka skillnader i muskelaktivering av sätes- och lårmuskler vid utförande av knäböj med skivstång i en fri jämfört med en fixerad vertikal rörelsebana hos friska idrottare under standardiserade förhållanden. Metod: Upprepade mätningar inom individer användes. Fem repetitioner knäböj per betingelse utfördes på en vikt som motsvarade 100% av deltagarnas egna kroppsvikt. Varje repetition genomfördes på fyra sekunder. Muskelaktivitet mättes med EMG-byxorna MBody3. Båda betingelserna testades under samma dag och deltagarna randomiserades till vilken förutsättning de skulle börja med. Resultat: Ingen skillnad observerades mellan betingelserna för medelvärdet av muskelaktiveringen under hela knäböjen. Mm. quadriceps och mm. hamstrings hade signifikant högre muskelaktivering i slutet av den excentriska och början av den koncentriska fasen av knäböjen då den utfördes i en fri rörelsebana. Ingen skillnad observerades, varken i hela eller delar av knäböjen, avseende m. gluteus maximus. Slutsats: Denna studie ger preliminära bevis på att muskelgrupperna mm. quadriceps och mm. hamstrings uppvisar lägre muskelaktivering i delar av knäböjen när den utförs i en Smithmaskin. Ingen signifikant skillnad observerades i muskelaktiveringen avseende hela rörelsen.
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Konrath, Jason Matthew. "A Morphological and Biomechanical Evaluation of the Semitendinosus and Gracilis After the Use of Hamstring Tendon for Anterior Cruciate Ligament Reconstruction". Thesis, Griffith University, 2017. http://hdl.handle.net/10072/368183.
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Injuries to the anterior cruciate ligament (ACL) are one of the most common knee injuries, with the majority occurring during non-contact manoeuvers such as side-stepping and single leg landing. Surgical intervention is generally required to restore stability to the tibiofemoral joint, unfortunately no perfect graft choice exists for reconstruction of the ACL, with all graft choices having potential advantages and disadvantages. The quadrupled hamstring autograft taken from the semitendinosus (ST) and gracilis (GR) muscles is a common choice for orthopaedic surgeons. However, harvest of the ST and GR tendons leads to post-operative donor muscle atrophy, as well as proximal retraction of the musculotendinous junction. This could in turn, have implications for tibiofemoral joint function, stability and loading. Thus, the overarching purpose of this thesis was to explore the morphological changes that occur to the donor muscles following tendon harvest and their biomechanical consequences.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Allied Health
Griffith Health
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Gustavsson, Robert, e Fredrik Eklund. "Styrkeförhållandet mellan knäflexorer och knäextensorer". Thesis, Mälardalens högskola, Akademin för hälsa, vård och välfärd, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-12205.
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Bakgrund: Inom forskningen studeras styrkeförhållandet i lårets muskler och anges ofta som flexor/extensor kvot (F/E-kvot). Ett sätt att mäta denna kvot är att använda isokinetiska styrketest. Forskningen är inte överens om ett optimalt styrkeförhållande i denna muskulatur eller om för stor styrkeskillnad kan ge upphov till skada. Om en optimal kvot kan fastställas är det intressant i ett förebyggande och rehabiliterande syfte. Syfte: Att beskriva och jämföra F/E-kvoten hos en grupp manliga fotbollsspelare med en grupp fysiskt aktiva män mellan 16 och 25 år. Metod: Mätning av maximal isokinetisk styrka i knäledens flexor och extensormuskler genomfördes med Genesis Single. Resultat: Studien fann en F/E-kvot hos fotbollsspelarna på 78,2 % på höger ben och 77 % på vänster ben. Jämförelsegruppen hade en F/E-kvot på 73,7 % på höger ben och76,4 % på vänster ben. Utifrån detta kunde man inte finna någon signifikant skillnad mellan de båda grupperna Slutsats: Studien fann ingen signifikant skillnad i F/E-kvot i höger respektive vänster ben mellan en grupp fotbollsspelare och jämförelsegrupp. Vidare forskning om reliabilitet och validitet med Genesis Single som mätinstrument bör utföras innan fler studier utförs med maskinen.Background: The kneeflexor and kneextensor muscle strength ratio (F/E ratio) is a widely researched area where isokinetic tests are often used. There seems to be little consensus regarding the optimal ratio and also whether a low ratio increase the risk of injury. It would be interesting from a preventive and rehabilitative stand point if an optimal ratio could be decided upon. Objectives: To compare the F/E ratio between a group of 16-25 year old soccer players and a group of physically active males. Methods: Isokinetic maximal strength in kneeflexors and kneextensors were measured with Genesis Single. Results: The ratio of the soccer players was 78,2 % in the right leg and 77 % in the left. The comparison group was found to have a ratio of 73,7 % in the right leg and 76,4 % in the left leg. There were no significant differences between the two groups. Conclusions: No significant differences could be determined between the two groups. Genesis Single needs to be further investigated with regards to its reliability and validity.
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Lindbäck, Kristoffer. "ACL reconstruction with a hamstring graft, can a forced foot dorsiflexion alter isokinetic knee flexion performance - a pilot study". Thesis, Luleå tekniska universitet, Hälsa och rehabilitering, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-74642.
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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.nej
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Messer, Daniel J. "Anterior cruciate ligament reconstruction and the hamstrings: Implications for injury prevention and rehabilitation". Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/118578/2/Daniel_Messer_Thesis.pdf.
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Both anterior cruciate ligament and hamstring strain injuries account for a significant amount of lost time in a range of football codes. This program of research has contributed new knowledge relating to the maladaptations which occur after anterior cruciate ligament injury and subsequent reconstruction, while also providing novel data which may be used to form decisions regarding exercise selection in anterior cruciate ligament and hamstring strain injury prevention and rehabilitation programs.
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Troubridge, Michael A. "The effect of foot position on quadriceps and hamstrings muscle activity during a parallel squat exercise". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ58097.pdf.
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Graham, Daniel Joseph. "The Long Term Effects of Short-Wave Diathermy and Long-Duration Static Stretch on Hamstring Flexibility". Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd624.pdf.
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Snyder, Alison R. "The acute influence of static and ballistic stretching on the biomechanics and muscle activity associated with the hamstring stretch". University of Toledo / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1102522627.
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German, Rachael M. "INHIBITORY KINESIO® TAPE APPLICATION TO THE HAMSTRING MUSCLE GROUP: AN INVESTIGATION OF ACTIVE RANGE OF MOTION AND PERCEIVED TIGHTNESS OVER TIME". Kent State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=kent1365289267.
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Law, Roberta. "Effects of a three-week hamstrings stretch program on muscle extensibility and stretch tolerance in patients with chronic musculoskeletal pain". Connect to full text, 2009. http://hdl.handle.net/2123/5420.
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Thesis (M. Phil.)--University of Sydney, 2009.Title from title screen (viewed September 25, 2009) Submitted in fulfilment of the requirements for the degree of Master of Philosophy to the Faculty of Medicine. Includes bibliographical references. Also available in print form.
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Silva, Dias Rosane da. "Eficacia de los tratamientos para la ganancia de flexibilidad en los musculos isquiotibiales. Meta-análisis". Doctoral thesis, Universidad de Murcia, 2009. http://hdl.handle.net/10803/10871.
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De acuerdo con la literatura científica, la frecuencia del acortamiento de los isquiotibiales, está relacionado con factores genéticos, hábitos diarios y actividades deportivas. Sin embargo, con las numerosas metodologías de tratamiento propuestas en la literatura se hace difícil establecer cuál de ellas resulta ser la más efectiva. En este trabajo se llevó a cabo meta-análisis sobre la eficacia de los tratamientos para la ganancia de flexibilidad en los músculos isquiotibiales. La búsqueda de la literatura permitió identificar 41 estudios, 39 publicados y 2 no publicados, entre 1930 y 2007, que cumplieron con los criterios de inclusión, totalizando 85 comparaciones entre grupo tratado y control. El índice del tamaño del efecto utilizado fue la diferencia de medias estandarizada. Los tratamientos obtuvieron una efectividad estadísticamente significativa (d+ = 1,054). El estiramiento muscular, más la combinación de estiramiento más calentamiento resultaron ser los tratamientos más efectivos. La relación entre el tamaño del efecto con las demás variables de tratamiento, de sujeto, metodológicas y extrínsecas, también fueron examinadas. El sesgo de publicación no fue una amenaza contra la validez de los resultados. Los tratamientos son más eficaces cuando: son empleados en sujetos del género femenino; cuanto más jóvenes sean los sujetos; y cuando se utiliza un número mayor de semanas de tratamiento.According to the scientific literature, the frequency of the shortened hamstring, is related to genetic factors, daily habits and sports activities. In spite of the found treatment methodologies diversity is difficult to establish which of them is more effective. In this paper we carried out a meta-analysis about the efficacy of the treatment for the increase the flexibility in the hamstring muscle. The searched of the literature enabled us identify 41 studies, 39 published and 2 no published, between 1930 and 2007, that fulfilled our the selection criteria, giving a total 85 comparisons between a treated an a control group. The effect size index was the standardized mean difference in the posttest. The treatments obtained a statistically significant effectiveness (d+ = 1,054). The stretching and stretching plus warming -up resulted to be the treatment more effective. The relationship of others treatment, subjects, methodological and extrinsic variables with the effect size were also examined. The publication bias was not a threat against the validity of the results. The treatments are more efficient when: they are applied in subjects of the feminine gender; the more young be the subjects and when a greater number of weeks of treatment are utilized
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Thompson, William Kevin. "T2 Mapping of Muscle Activation During Single-Leg Vertical Jumping Exercise". Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1194982561.
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Fondran, Kristine Marie. "THE EFFECT OF SURYA NAMASKARA YOGA PRACTICE ON RESTING HEART RATE AND BLOOD PRESSURE, FLEXIBILITY, UPPER BODY MUSCLE ENDURANCE, AND PERCEIVED WELL-BEING IN HEALTHY ADULTS". Cleveland State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=csu1220456637.
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Comellini, Gianmarco. "Lo strappo muscolare degli ischiocrurali nello sportivo. L?efficacia della fisioterapia nella prevenzione delle recidive: revisione sistematica della letteratura". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
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ABSTRACT
Background: lo strappo muscolare degli ischiocrurali è un infortunio molto diffuso nel mondo dello sport. Il suo tasso di recidiva è molto alto e nella maggior parte dei casi costringe gli atleti a fermarsi per lunghi periodi. In base alla gravità della lesione possono comparire spasmi, rigidità, indolenzimento muscolare, gonfiore, dolore, menomazione di funzione.
In letteratura sono presenti diverse proposte di trattamento fisioterapico ma non è ancora chiaro quale di queste sia più efficace nel ridurre il rischio di recidiva e la durata del periodo riabilitativo.
Obiettivi: lo scopo di questa revisione sistematica della letteratura è valutare l’efficacia del trattamento dello strappo muscolare degli ischiocrurali nella riduzione del rischio in recidiva e, come outcome secondario, nella riduzione del tempo necessario per il ritorno allo sport.
Metodi di ricerca: le ricerche sono state effettuate sulle banche dati di PubMed, PEDro, CINAHL Complete, Cochrane Library e SPORT Discus tra giugno e agosto 2019. Sono stati inclusi solo RCT che indagavano l’efficacia di programmi riabilitativi composti da esercizi di rinforzo, esercizi di allungamento ed esercizi di controllo del bacino.
Risultati: sono stati selezionati 5 RCT. Le misure di outcome prese in esame riguardano: il numero di recidive all’interno di un anno di follow-up, la durata del periodo riabilitativo e il tempo necessario per tornare all’attività sportiva.
Conclusioni: Il reclutamento della muscolatura del tronco e del bacino combinato con esercizi di allungamento e di rinforzo potrebbe portare ad una diminuzione delle recidive e della durata del periodo riabilitativo, infatti, il reclutamento del Core durante l’esecuzione degli esercizi potrebbe favorire ad un miglioramento della funzione muscolare e un miglioramento della resistenza dei muscoli agli stress fisici più intensi.
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Reid, Duncan A. "The effects of acute and periodic stretching interventions on knee extension range of motion and hamstring muscle extensibility in individuals with osteoarthritis of the knee a thesis submitted in partial fulfilment for the degree of Doctor of Health Science, Auckland University of Technology, November 2008". Click here to access this resource online, 2008. http://hdl.handle.net/10292/647.
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Behan, Fearghal. "Neuromechanics of explosive performance for movement control and joint stabilisation". Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/28123.
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The broad aim of this thesis was to progress understanding of the neuromechanics of joint stability and injury mechanisms by investigating the interactions between neuromuscular function and balance perturbations as well as the influence of sex and fatigue on these variables. Knee extensor (KE) and plantar flexor (PF) isometric strength parameters (maximum voluntary torque (MVT), explosive voluntary torque (EVT)) were related in young healthy adults. EVT of KE and PF were correlated at 4/5 time points during the rising torque-time curve for all absolute (r = 0.488-0.755) and relative (to body mass (BM) (r = 0.517-0.669) and MVT (r = 0.353-0.480)) expressions of EVT. These results suggest that KE and PF function is related for both maximum and explosive torque. Males were stronger for KE (+89%) and PF (+55%) than females. Males also displayed greater EVT at all time points in KE (+57-109%) and at 50-150 ms in PF (+33-52%). When MVT and EVT were normalised to BM, males continued to be stronger at all time points in KE (+23-60%) and from 100-150 ms (18-20%) in PF. No sex differences were found when EVT was normalised to MVT. Furthermore, sex differences were discovered in muscle morphology. Females had a smaller knee flexor (KF):KE size ratio, a proportionately small sartorius (SA) and gracilis (GR) and a proportionately larger vastus lateralis (VL), potentially predisposing females to greater risk of ACL injury. Females had a larger biceps femoris long head (BFlh) as a proportion of the KF than males, which may contribute to the higher risk of hamstring strain injury (HSI) in males. Regarding explosive performance and perturbation response, explosive PF torque had a weak to moderate correlation with COM displacement (COMD) from 400-500 ms (r = -0.346 to -0.508) and COM velocity (COMV) from 300-500 ms (r = -0.349 to -0.416), with weaker correlations between explosive KE torque and COMV at 400 ms (r = -0.381 to -0.411) but not with COMD. These findings suggest that greater explosive torque results in better control of the COM in response to unexpected perturbations. The effects of football simulated fatigue on these factors resulted in reduced maximal KF and KE torque. However, football simulated fatigue was not found to reduce EVT of either muscle group, or explosive H/Q ratio. Football simulated fatigue resulted in impaired balance response to unexpected perturbation in the posterior but not the anterior direction.
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Westdorp, Clayton Mathew. "The Influence of Focal Knee Joint Cooling on Thigh Neuromechanical Function". University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1556626975273872.
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Jones, Robert Ian. "The influence of soccer-specific fatigue on the risk of thigh injuries in amateur black African players". Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1001841.
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Background: Epidemiological findings indicate a higher risk of muscular thigh strain injury during the latter stages of both halves of soccer match-play, with muscular fatigue highlighted as a key etiological factor in injury causation. Anthropometric, biomechanical and physiological differences present in the Black African population may elicit unique thigh injury risk profiles, different from those of European and American players. Objectives: The purpose of the current research was to investigate the impact of soccer-specific fatigue on the risk of hamstring and quadricep injury in amateur Black African soccer players, in both the dominant and non-dominant legs. Methods: Participants were required to perform a soccer matchplay simulation (SAFT⁹⁰), consisting of multidirectional and utility movements, as well as frequent acceleration and deceleration. Selected physical, physiological and psychophysical responses were collected at specific time intervals throughout fatigue protocol performance. Results: Heart rate responses were observed to increase significantly (p<0.05) in response to the start of both halves, and remain elevated (but showing no further significant increase) during the performance of the remainder of the fatigue protocol. Significant (p<0.05) changes in both concentric and eccentric isokinetic variables of the knee flexors and extensors highlight the effect of muscular fatigue on performance in soccer match-play. Eccentric hamstring peak torque was observed to decrease significantly over time (60°.s⁻ₑ=17.34%, 180°.s⁻ₑ=18.27%), with significant reductions observed during both halves. The functional H:Q ratio at 180°.s⁻ₑ indicated a significant decrease over time (10.04%), with a significant decrease indicated during the second half of the SAFT⁹⁰ protocol. The passive half time interval did not result in significant changes in isokinetic variables. Isokinetic strength, work and power indicated no significant effects of leg dominance.. ‘Central’ and ‘Local’ ratings of exertion were observed to increase significantly (p<0.05) as a function of exercise duration. Conclusion: The overall reduction in both the eccentric hamstring peak torque and the functional strength ratio was illustrated to be similar to that of other soccer-specific fatigue research. As a result, the risk of thigh strain injuries is suggested to be similar regardless of playing level and race. These time dependent changes may have implications for competitive performance and increased predisposition to hamstring strain injuries during the latter stages of both halves of match-play