Dissertations / Theses on the topic 'Physiological aspects of Winter sports'

The purpose of this investigation was to examine the contractile properties of individual slow and fast myofibers in response to various training periods throughout a collegiate cross-country season in male runners. Muscle biopsies were obtained from the gastrocnemius of five runners at three time points during the season; after a summer aerobic training phase (T1); after an 8 week period of intense training (T2) and after a 4 week taper period (T3). Absolute (4.6±0.3 L/min) and relative (71±0.7 mI/kg/min) maximal oxygen consumption were unchanged during the study duration. Run performance (8 km) improved 3% from T1 to T2 (27:26 to 26:38 min:sec) and 1% from T2 to T3 (26:21 min:sec). A total of 328 individual myofibers were isolated and studied at 15°C. MHC I diameter was 3% lower (P < 0.05) at T2 compared to T1 and 4% smaller at T3 compared to T2. MHC I and Ila fibers were 18 and 11 % stronger (P < 0.05) respectively, from T1 to T2. MHC I fibers produced 9% less force (P < 0.05) after the taper (T2-T3) while MHC Ila fibers were 9% stronger (P < 0.05). Specific tension (Po/CSA) increased (P < 0.05) 38 and 26% for MHC I and Ila fibers, respectively from T1 to T2 and was unchanged with the taper. Maximal shortening velocity (Vo) of the MHC I fibers decreased (P < 0.05) 23% from T1 to T2 and 17% from T2 to T3. MHC I peak power decreased (P < 0.05) 20% from T1 to T2 and 25% from T2 to T3. Power corrected for cell size decreased (P < 0.05) 15% from T2 to T3 and was 24% lower at T3 compared to T1 for the MHC I fibers only. MHC Ila diameter, Vo, peak and normalized power were unaltered during the study duration. These data suggest that myocellular function is sensitive to changes in run training and it appears that MHC I fibers are moreaffected than MHC IIa fibers. Furthermore, the increase in interval training with the taper may have offset the modest reduction in training volume and prevented any positive adaptations at the cellular level.
Human Performance Laboratory

The purpose of this study was to examine the effects of a 4-week reduction in training volume and intensity on performance of distance runners. Ten well-conditioned males underwent 4-weeks of base training (BT) at their accustomed training distance (71.8 ± 3.6 km/wk) and pace (76% of total distance above 70% V02 max intensity), before reducing training (RT) for an additional 4 weeks. Training volume was decreased by -.66% to 24.8 km/wk and frequency by 50% to 3 runs per week. Training intensity was reduced such that all running was at less than 70% V02 max (68.2 ± 1.6%). At the end of BT (week 0), and weeks 2 and 4 of RT, resting heart rate, calculated plasma volume, testosterone and cortisol levels, and submaximal treadmill efficiency were assessed. At weeks 0 and 4, V02 max and 5 kilometer race performance was determined. The ratio of testosterone to cortisol was increased significantly with RT (0.054 ± 0.008 at week 0 to 0.082 ± 0.020 at week 4), although the individual testosterone and cortisol concentrations were not significantly altered. Maximum oxygen consumption, and time to exhaustion during the max tests were not altered with RT. Body weight tended to increase (p=0.09) due to a significant increase in percent body fat (p<0.05). Submaximal treadmill runs at 65%, 85%, and 95% V02 max revealed no alterations in absolute V02 while relative V02 decreased significantly. This decrease in relative V02 was due partially to the weight increases and partially to a significant increase in respiratory exchange ratio (RER). Resting and submaximal treadmill heart rate (HR) were unchanged with FIT, while maximal treadmill HR and race HR were increased significantly. Calculated plasma volume was unaltered. Leg and overall ratings of perceived exertion were decreased during RT with the overall rating reaching significance (p<0.05). Blood lactic acid concentration was found to be significantly higher at the 95% V02 max workload following RT (8.39 ± 0.46 vs 9.89 ± 0.46 mmol/L at week 0 and 4, respectively). Five kilometer race time increased significantly from 16.6 ± 0.3 at week 0 to 16.8 ± 0.3 minutes at week 4 (12.1 seconds). It is concluded that a 4-week reduction in training volume and intensity in these runners resulted in a significant decrease in race performance despite the maintenance of aerobic capacity.
School of Physical Education

The purpose of this study was to examine the effects of event order on a cycling(C)/running(R) or R/C biathlon. Eight experienced male biathlete/triathletes with a mean age of 24.9 + 4.6 yr formed the sample of the study. Results show no significant interaction effects on oxygen consumption peak, oxygen consumption during steady-state, ventilation, and heart rate when C/R or R/C are performed at 70% oxygen consumption peak for subsequent R and C respectively. These results seem to indicate that the biathlete/triathlete is efficient in both C and R to the extent that event order does not significantly interact with metabolic response in submaximal cycling and running.

In competitive golf, the player’s ability to hit the ball a long distance affects the score in a positive way. Swing kinematics is considered an important factor in driver performance; one way of improving swing kinematics is through strength and power training. Subsequently, high-level golfers and their coaches often explore novel ways of increasing the distance of a shot, in particular driver carry distance (CD). This licentiate thesis presents two studies with the overall aim of studying how swing kinematic and physical characteristics are associated with driver performance among intercollegiate golf players. The studies report swing kinematics associated with driver performance (study 1) and the impact of isokinetic rotational training on driver performance and swing kinematic variables (study 2). The methods used were (1) a cross-sectional correlation study (n=15) and (2) an open trial intervention study (n=20). The studies investigated (1) the relationship between golf swing kinematics and driver performance, and (2) the impact of strength training on swing kinematics and driver performance variable. The results show variables that were distinctive for the club head speed (CHS) were mainly during the downswing: greater X-factor stretch; and higher pelvis peak speed. Whilst, factors distinctive to the regression model for CD were mainly at impact: reduced thorax rotation; and greater thorax lateral bend. Nine weeks of isokinetic training increased seated rotational force and power, peak arm speed and arm acceleration, ball speed, and CD more compared to isotonic training. Even though isokinetic training did not increase CHS, it did result in greater CD. This licentiate thesis contributes to the understanding of which variables influence driver performance, in particular CD, among high-level golfers. Segmental interactions (pelvis-thorax), lead arm speed and acceleration, isokinetic and isotonic training. These results may guide training interventions aiming to improve driver and golf performance among high-level golfers, particularly those with a background of strength training. Future studies could investigate how the interaction between swing kinematics, clubhead trajectory, and driver performance variables differ between male and female golfers.

Due to limited research in the field testing of youth sport, specifically with regard to females, this project was delimited to the examination of the responses of youth participants in relation to the nature of the sport, when participating under conditions of competitive stress. It further attempted to elucidate gender related differences within these responses. Forty four male and female subjects aged 15 - 19 years volunteered to participate in this study; all pupils were First team members who competed in a variety of team and individual sports. Subjects participated in a battery of psychological, physiological and performance tests before and after competing in a practice session and during competitive league matches. The data were statistically analyzed for the various parameters under investigation. The results of the Sport Competition Anxiety Test indicated that the females, and the male team players had the highest competitive anxiety traits (CTA). The Task and Ego Orientation in Sport Questionnaire scores showed that most subjects have a general dominance of task orientation to sport. The results of the Physical Self-Perception Profile revealed that the females' poorer perception of their physical was not as substantial as their difference in CTA compared to males. Team participants, particularly the males, had a poorer self-image than individual sport counterparts. Elevated heart rate responses were observed prior to performing in a competitive ambience, with significant increases in team, rather than individual, players. The Evaluation of Task Demands revealed that team players, especially the females, perceived the match demands as significantly higher than the individual athletes. No significant differences were observed in the players' Evaluation of Perceived Strain. Neither were any significant differences observed in the players' ratings of their performance. In conclusion, although differences appear to exist between male and female responses within a competitive ambience, the magnitude of difference was far more notable between team and individual responses to competitive stress, particularly for competitive matches as opposed to practice sessions.

This study aimed to distinguish the coping efforts of athletes who endured shorter, and longer, durations of competitive suffering. Eleven male and 15 female endurance athletes (Mage= 35.8, sd= 12.1) completed a 5km competitive suffering running time-trial task. Following the task, threat perceptions and coping function use (problem focused, PFC; emotion focused, EFC; and avoidance, AvC) were measured in 200 meter intervals using video mediated recall. Control beliefs were also assessed. Those who suffered for shorter durations used more EFC during initiation and at the peak of competitive suffering, as well as less AvC during initiation, in comparison to longer duration sufferers. PFC use did not distinguish competitive suffering duration. Non-significant correlations were revealed between control beliefs and both suffering duration and coping function use. Overall, the results imply that emotion-focused coping is the most appropriate coping function to decrease competitive suffering duration, regardless of control beliefs.
xi, 106 leaves : ill. ; 29 cm

This investigation examined the heart rate responses and movement characteristics of experienced footbag net players during singles play. Footbag net is a net/court sport similar to volleyball, but it is played with a footbag (e.g., Hacky-SackTM) using only the feet. In singles footbag net, players are allowed either one or two kicks to propel the footbag over the net. Subjects were 15 males and 1 female, ranging in age from 18- 60 years, with a mean age of 33.6 years. Subjects played two games of singles footbag net using two different scoring systems: "sideout" scoring and "rally" scoring. Mean heart rates were 149.4 bpm for games played under the sideout scoring system and 148.7 bpm for games played under the rally scoring system. Sideout games were 1.2 minutes (~11%) longer than rally games. The mean heart rate responses to competitive play using sideout scoring and rally scoring were not significantly different (p>0.05). For play under both scoring systems, the average exercise intensity--expressed as a percentage of age-predicted maximum heart rate (MHRest)--was 80-81% MHRest. Accelerometer counts accumulated during play were similar for both scoring systems. It is recommended that additional research be conducted to evaluate the extent to which accelerometry may contribute to physiological and metabolic measurements of footbag net competition.

Little is known about the strain and consequences of very prolonged and sustained exercise lasting multiple days. This thesis comprises two multi-day exercise field studies and a 24-h, controlled-trial field/laboratory study. The field studies were undertaken using international adventure races (2003 and 2004 Southern Traverses: 86-120 h) to profile exercise intensity and associated physiological and psychophysical strain, and physical and cognitive performance. The 2003 study showed that exercise intensity (from heart rate range) averaged 64% during the first 12 h, dropped to 41% by 24 h, and remained so thereafter. Body core temperature (gastrointestinal pills), throughout racing (n=8) was relatively stable (min 36.0�C and only briefly >39�C), despite widely varying endogenous and exogenous thermal stress. Blood samples obtained before (n=34), during (n=11) and after (n=34) racing revealed a large plasma volume expansion (24%), with stable [sodium]plasma (n=6). Acute (15-30 h) and chronic (96-120 h) elevation of neutrophil, monocyte and lymphocyte numbers were observed across the race. Standardised exercise tests (rest, 25 and 50% peak power output (PPO)) before and after racing (n=9) revealed an extreme shift toward fat utilisation, consistent with lowered fat mass (11%; n=44) and high [free fatty acids]plasma (up 370%; n=9) at race-finish, although [HAD]muscle was unchanged. Muscle glycogen was only 50% lower post-race (290 nmol�kg⁻�d.w.). Complex cognitive performance (Stroop test) impairment was attenuated during 50% PPO post-race. Perceived exertion uncoupled from HR at standardised workloads. Explosive power (jump test; n=24) and anaerobic power (30-s Wingate; n=27) were modestly (<10%) impacted. Strength reduction of arms (11%) and legs (17%) was equivalent (p=0.17). The 2004 study (n=4) involved dissimilar terrain, vegetation, and sequence of exercise modes, yet the profile of exercise intensity was similar: first 12 h 65%, then 45% by 24 h and thereafter. Thus, athletes reliably attain sustainable, low-to-moderate exercise intensity by 24 h. Plasma volume, neutrophil and monocyte responses were reliable across races, whereas lymphocytes were not. Plasma [IL-6] and [S100β] were elevated, substantially in some individuals (IL-6: 223 pg�mL⁻�; S100β: 113 pg�mL⁻�), during racing. A 24-h adventure race simulation (n=9) was then undertaken to investigate physiological and psychophysical factors influencing exercise intensity, autonomic function and orthostatic tolerance. Tests were at 0, ~7, ~15 and 24 h. The 24-h HR profile matched that observed during racing: first 12 h 58% (including 3-h testing), remainder 41%. The shift toward fat utilisation was almost complete within 7 h, and similar to that following 2003 race. The perceived exertion-to-HR uncoupling was also similar; being complete within 15 h. Plasma [noradrenaline] for rest and 12-km�h⁻� run was elevated post-simulation. Plasma [IL-6] peaked by 7 h, although not as high as field observations. The timeframe of metabolic change and perceived exertion uncoupling coincided with that of pace reduction, and may be important regulatory components of very prolonged exercise intensity. Orthostatic intolerance was evident during the simulation (n=6/9), as was cerebral hypo-perfusion (15 h & 24 h). Autonomic function (baroreflex sensitivity, sympathetic activation, parasympathetic withdrawal) was altered only at 7 h, whereas postural-induced hypotension (via impaired venous response) and hypocapnia were always present.

The purpose of this study was to investigate the relationships between the arm joint angle at contact-release with peak velocity in experienced cerebral palsied athletes during wheelchair propulsion. The subjects (n = 5) exercised for a few minutes to familiarize themselves with the roller set up. After practice, each subject was asked to push the wheelchair as fast as possible up to 10 seconds. A tach-generator was attached to the core of the roller and interfaced to a computer via an eight bit A/D converter. The sampling rate of the roller speed was 200Hz. One video camera operating at 30 frames per second, and posisioned 7 m from the roller side was used. The data were analyzed for shoulder, elbow, and wrist angles with the Peak Performance program in I.B.M. compatible computer. Subjects' peak velocities were 8.85, 4.49, 4.19, 3.66, and 4.09 m/s, and the mean percent of contact and release times were 32.8% vs 67.2%. Shoulder, elbow, and wrist contact angles were not statisticaly in this study. Results indicate that contact-release angle on hand-handrim was effected for peak velocity. Also there was no significantrelationship between speed and cycle time.Key WordsRacing wheelchair, cerebral palsy, Peak velocity, Propulsion, Joint angle.
School of Physical Education

The use of a structured goal setting program in injury rehabilitation has not been empirically tested, but many others have noted that its use could increase compliance. The primary purpose of this study was to determine the effect of a structured goal setting program on individuals' compliance to injury rehabilitation; secondly, to examine the hardiness levels of those individuals, and determine if there was a relationship between their levels of hardiness and compliance to the treatment. Individuals who sought services of Ball Memorial Hospital Health Strategies for a back injury (N = 15) participated by first completing the Personal Views Survey. Then, the control group ( = 6) completed their normal rehabilitation program, while the experimental group ( = 9) completed their rehabilitation program using a structured goal setting program. Finally, both groups completed a post-hardiness survey. The researcher found no significant difference in compliance rates between the two groups. All of the injured participants recorded moderate hardiness levels and a low correlation was observed between hardiness and compliance to treatment.
School of Physical Education

Athletes have continually sought to improve their physical performance. In order to accomplish this, athletes experiment with performance enhancing drugs, which are readily available to the athlete today. Cocaine, being one of them, is traditionally and popularly believed to increase muscular endurance and possess anti-fatiguing properties. The scientific literature as to whether cocaine is truly a performance enhancing drug is inconclusive. Moreover, few if any studies have been conducted on exercise performance following long term, repeated cocaine administration. The purpose of the present study was to determine the effects of 35 days of cocaine administration (25 mg/kg/day) on maximal endurance exercise capacity. Data were collected from six untrained male Sprague-Dawley rats. Resting and exercise heart rate and body temperature were recorded via radio telemetery. Running time to exhaustion was recorded via one weekly maximal treadmill exercise bout to exhaustion (26 m/min, at a 10% grade). Compared to saline controls, cocaine significantly decreased run time to exhaustion, following acute and chronic administration. Cocaine administration also significantly decreased maximal exercise heart rate. Chronic cocaine had minimal effects on resting heart rate and resting and exercise body temperature during maximal exercise conditions. These data indicate that daily, chronic cocaine administration significantly reduces endurance exercise capacity, and suggests that the decreased physical work capacity following cocaine is related to a decreased ability of the heart to function under maximal exercise conditions.

The purpose of this investigation was to examine the effects of 20 years of distance running training on the morphological and functional characteristics of skeletal muscle. Sixty men (current age = 49.2 ± 2.4 yr.) were first studied between 1966-1974 when they were all highly trained. Based on their training regimens in the interim between testing, subjects were described as highly trained (HI), fitness trained (FIT) or untrained (UT). Gastrocnemius muscle biopsy samples revealed an increase (p<0.05) in the proportion of type I fibers of the FIT (52.9 ± 5.3 vs. 61.9 ± 5.2%) and UT (56.3 ± 2.9 vs. 65.4 ± 3.8%) groups, while the HI group, who was initially characterized by a high percentage (>70%) of type I muscle fibers, was unchanged. Among the elite distance runners who had continued high volume, high intensity running, succinate dehydrogenase (SDH) activity and type I and type II muscle fiber areas were similar between evaluations. In 1993, the HI group had higher (p<0.05) SDH and citrate synthase (CS) activities compared with the FIT and UT groups, whereas phosphorylase activity did not differ. Capillary density and capillary-to-fiber ratio were also greater (p<0.05) in the HI group compared with the other two groups. Isokinetic plantar flexion strength at 60°/s and 180°/s and cross-sectional area (CT scans) of the lower leg (gastrocnemius and soleus) were similar among groups. These data suggest that aging may have a significant effect upon the distribution of muscle fibers and may be dependent upon fiber composition as a young adult. In addition, sustained endurance training appears to maintain the oxidative characteristics of the skeletal muscle, but does not provide an advantage in absolute calf muscle strength compared with individuals who train considerably less or not at all.
School of Physical Education

[Truncated astract] Talent Identification (TI) in sports begins by mass screening individuals' motor abilities. du Randt (2000) wrote that, as test items from one country might not necessarily suit another, appropriate basic motor skill test items are important for developing a TI mass screening instrument. Three hundred and thirty Malaysian adolescents aged from 12-15 years were tested on three motor skill test batteries: the McCarron Assessment of Neuromuscular Development (MAND, McCarron, 1982); the Australian Talent Identification Test (AIS, Australian Sports Commission, 1998); and a Balance and Movement Coordination Test which was specifically developed for this project. In the current research, the motor performance data recorded from the adolescents underwent several types of analyses. Principal Component analyses were conducted on the MAND, AIS and BMC motor skill instruments to understand what the three motor skill instruments were assessing globally in the Malaysian adolescents. Then, first-order and higher-order factor analyses were conducted on the 13 parameters making up the AIS+BMC motor skill instrument to examine the concept of general motor ability (GMA). After descriptive analyses of the adolescents' motor skill performances, age and gender differences were examined using two (gender) by four (age) ANOVAs. Finally, stepwise discriminant function analyses were conducted on a combined AIS+BMC motor skill instrument to determine the best sub-set of motor skills that reliably classified the Malaysian adolescents into three levels of motor performance.... Two stepwise discriminant analyses were undertaken to find the best set of motor skills for classifying Malaysian adolescents into three motor coordination groups based on scores on the MAND and three motor ability groups derived from scores on the motoric 'g'. The ability of a combined AIS+BMC motor skill instrument to classify Malaysian adolescents into the three groups was good for those classified as Normal, not so great for those adolescents classified as High, and poor for those adolescents classified as Low. The motor skills consistently reported across both sets of analyses were Balance-Eyes-Open, Balance-Eyes-Closed, Dynamic Balance, Hopping Speed, Quadrant Jump, Hopping-in-Square, Basketball Throw and Shuttle-Run-with-Object. Hence, motor skills assessing static balance, dynamic balance and postural control appeared to reliably discriminate the Malaysian adolescents into three motor performance groups. Finally, an examination of the misclassifications found in the discriminant analyses revealed two things. Those individuals being predicted into a lower group performed a large number of the motor skills to a lesser standard when compared with their correctly classified cohorts. Conversely, those predicted into a higher group performed a number of motor skills to a standard higher than their correctly classified cohorts. Thus, at a global level, certain individuals could be overlooked for further athletic development and is a concern when developing a rigorous TI program. Therefore, practitioners need to be cautious of any single ability score, and how that represents an individual's athletic potential. These results are discussed, limitations noted, and directions for future research provided.

The purpose of this project was to review anterior cruciate ligament (ACL) literature and develop a performance evaluation and injury risk assessment (PIER) for female soccer players. A strategy guide for decreasing injury risk and enhancing performance was developed in hopes to bring awareness to the athletic community about ACL injury for female soccer players.

Thesis (M Sport Sc)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: Compression socks (CS) are used as an ergogenic aid during and after exercise by many athletes of elite and recreational status. The exact mechanism whereby CS affect performance and postexercise recovery is not yet elucidated. Some research ascribes the beneficial effects to improved lactate removal rates with CS. One hypothesis is that CS improve venous return and thereby remove the lactate from the tissue to other tissues such as the liver, and the second hypothesis is that the CS cause retention of the lactate within the muscle and therefore improve the oxidation of the lactate within the muscle (Berry & McMurray, 1987). The current study endeavoured to test the hypothesis set by Berry and McMurray (1987) by measuring the effect of CS as well as flight socks (FS) on muscle oxygenation during exercise and recovery in endurance trained runners and triathletes. Eleven male endurance trained runners and triathletes (age = 34.8 ± 3.8 years, VO2max = 52.4 ± 7.1 mL.kg-1.min-1) participated in the study. They completed an incremental exercise test to exhaustion to determine their maximal aerobic capacity (VO2max) and peak treadmill velocity (PTV). Then they completed two 10 km treadmill running tests at 80 % of their PTV. During these two trials participants wore either CS or FS; the order of treatment was randomly selected. A subset of the study sample (n = 5) also completed a control test wearing only their ankle length sport socks (NS). After these trials, participants completed a 60 minute passive recovery period in the seated position while muscle oxygenation was measured. Compression under the socks was measured at several anatomically determined measurement points prior to the commencement of the exercise test, along with the determination of blood haemoglobin concentration ([Hb]). During the exercise trials, blood lactate concentration ([BLa]), skin temperature (ST),oxygen consumption (VO2), carbon dioxide production (VCO2), heart rate (HR), and muscle oxygenation variables (oxy-haemoglobin (O2Hb), deoxy-haemoglobin (HHb), tissue oxygenation index (TOI) and total haemoglobin index (nTHI)) was measured . During the 60minute passive recovery period, [BLa], ST, O2Hb, HHb, TOI, and nTHI measurements were continued. The results showed that there were differences in the pressure exerted between the two pressure condition (CS and FS) at the posterior ankle, and under the elastic of the sock as well as on the anterior calf at the level of greatest calf circumference. Differences in ST between the CS and NS and the FS and NS conditions were found between the first four 2 km intervals of the exercise protocol, but not during recovery. No differences were found in [BLa] between the three different compression conditions during either the exercise (p = 0.19) or recovery period (p = 0.63), as well as no differences in the cardiorespiratory variables during exercise between the three different compression conditions (VO2, p = 0.06; VCO2, p = 0.12; HR, p = 0.36). With regard to the muscle oxygenation variables, no differences were found between the three compression conditions during exercise, however there was a trend for lower oxygen utilization (HHb) during exercise in the NS condition (p = 0.57, medium to large practical significance). There were also no differences in these variables (O2Hb, p = 0.65; HHb, p = 0.57; TOI, p = 0.39; nTHI, p = 0.22) during recovery, although oxygen utilization (HHb) showed a faster recovery rate with increasing external pressure. From the results obtained, it seems that external compression caused a decrease in the blood flow velocity within the muscle, thereby increasing oxygen diffusion rate. During exercise this did not facilitate differences in [BLa], however, after the first 10 minutes of the recovery period, large practical differences were found between the NS and both sock conditions, suggesting that the increase in oxygen diffusion improved lactate clearance. This could support the hypothesis set by Berry and McMurray (1987).
AFRIKAANSE OPSOMMING: Kompressie sokkies (CS) word gereeld deur beide rekreasie- en elite atlete gebruik as ‘n ergogeniese hulpmiddlel tydens oefening en herstel. Die presiese meganisme waardeur CS prestasie en post-oefening herstel beïnvloed is nog nie volledig verklaar nie. Sommige navorsing skryf die voordelige effekte toe aan die vinniger herstel van laktaat in die sirkulasie. Daar is tans twee hipoteses vir die meganisme waardeur CS laktaat verwydering verbeter. Die eerste hipotese is dat CS die veneuse terugvoer verbeter en daardeur die laktaat van die weefsel verwyder en na ander weefsels soos die lewer vervoer vir verwydering. Die tweede hipotese is dat CS veroorsaak dat die laktaat in die spierweefsel teruggehou word wat dan tot gevolg het dat die laktaat in die spier self deur middel van oksidasie verwyder word (Berry & McMurray, 1987). Hierdie studie poog om Berry en McMurray (1987) se hipotese te toets deur die effek wat CS sowel as vlugsokkies (FS) op spieroksigenasie het gedurende oefening en herstel in geoefende uithouvermoë hardlopers en driekamp atlete vas te stel. Elf ingeoefende langafstand hardlopers en driekampatlete (mans) (ouderdom = 34.8 ± 3.8 jaar; VO2maks = 52.4 ± 7.1 mL.kg-1.min-1) het aan hierdie studie deel geneem. Die deelnemers het ‘n inkrementele toets tot die punt van uitputting voltooi om hul maksimale aërobiese kapasiteit (VO2maks) en piek trapmeul snelheid (PTV) vas te stel. Die elf deelnemers het ook twee 10 km hardlooptoetse teen 80 % van hul PTV voltooi. Gedurende hierdie twee toetse het die deelnemers óf CS óf FS gedra; die volgorde van die intervensie was lukraak aan hulle toegeken. ‘n Subgroep van die steekproef (n = 5) het ook ‘n kontrole toets voltooi waartydens hulle hul eie enkelhoogte sport sokkies (NS) gedra het. Aan die einde van die hardloop protokol het die deelnemers ‘n 60 minuut passiewe herstel periode in die sittende posisie voltooi terwyl spieroksigenasie gemeet is. Kompressie onder die sokkies is voor die aanvang van die hardloop protokol by verskeie anatomies gedefinieerde punte gemeet. Verder was die bloed hemoglobien konsentrasie ([Hb]) ook gemeet voor die hardloop protokol. Tydens die oefeningtoets is bloedlaktaat konsentrasie ([Hb]), veltemperatuur (ST), suurstof verbruik (VO2), koolstofdioksied produksie (VCO2), harttempo (HR), sowel as spieroksigenasie veranderlikes (oksi-hemoglobien (O2Hb), deoksi-hemoglobien (HHb), weefsel oksigenasie indeks (TOI), en totale hemoglobien indeks (nTHI)) gemeet. Gedurende die 60 minuut passiewe hersteltydperk is [BLa], ST, O2Hb, HHb, TOI en nTHI metings geneem. Die resultate toon dat daar ‘n verskil is in die druk wat uitgeoefen word in die onderskeie druktoestande (CS en FS) op die been by die posterior enkel en onder die rek van die sokkie, sowel as op die anterior kuit waar die kuit die grootste omtrek het. Verdere verskille tussen die CS en NS en die FS en NS toestande is in ST gevind in the eerste vier 2 km intervalle van die oefeningtoets, alhoewel geen verskille tydens die herstelperiode gevind is nie. Tydens beide die oefening (p = 0.19) en herstel (p = 0.63) protokol is geen verskille tussen die drie kompressie toestande met betrekking tot [BLa] gevind nie. En so ook is daar geen verskille tussen die onderskeie kompressie toestande in kardiorespiratoriese veranderlikes (VO2, p = 0.06; VCO2, p = 0.12; HR, p = 0.36) tydens oefening gevind nie. Met betrekking tot spieroksigenasie veranderlikes was daar geen verskil gevind tussen die drie kompressietoestande gedurende oefening nie, alhoewel daar ‘n tendens was vir die NS toestand om tydens oefening minder suurstofverbruik (HHb) (p = 0.57, medium tot groot praktiese effek) te lewer. So ook gedurende herstel is daar geen verskil in hierdie veranderlikes (O2Hb, p = 0.65; HHb, p = 0.57; TOI, p = 0.39; nTHI, p = 0.22) gevind nie, alhoewel die suurstofverbruik (HHb) vinniger na die basislyn herstel het met ‘n toename in druk. Die resultate toon dat eksterne kompressie ‘n afname in die bloedvloei tempo in die spier veroorsaak wat dan ‘n verlengde suurstof diffusie tyd veroorsaak. Hierdie verlengde suurstof diffusie tyd het geen effek op [BLa] tydens oefening gehad nie, alhoewel daar na die eerste 10 minute van die herstelperiode ‘n groot praktiese verskil tussen die NS en sokkie toestande gevind was in [BLa]. Hierdie verskil kan daarop dui dat die toename in suurstof diffusie verbeterde laktaat verwydering tot gevolg het, wat dan die hipotese van Berry en McMurray (1987) ondersteun.