Thesis (PhD (Sport Sc) (Sport Science))--University of Stellenbosch, 2011. / Please refer to full text to view abstract.

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.

Muscular fatigue limits athletic performance as well as activities of daily living that require repetitive or sustained contractile activity. The decrease in force output or inability to maintain a given force level during fatigue occurs as the result of neural and muscle physiological factors. In contrast to muscle fatigue, potentiation is an increase in muscle force following voluntary muscle activity. The simultaneously occurring processes of potentiation and fatigue influence force output. The aims of this research were to investigate parameters used to potentiate muscle via electrical stimulation and voluntary contraction, and to better understand how muscle force is sustained, we studied single motor unit firing patterns and force potentiation following muscular endurance training. In study 1, electrical stimulation trains matched for pulse number of various frequencies and of increasing pulse number at a given frequency were administered to determine the effects of these stimulation parameters and of the force-time integral (FTI) produced during the train on potentiation magnitude. No difference in potentiation magnitude was found across trains of matched pulse number for frequencies of 15, 25, 30 and 50 Hz. Potentiation increased as pulse number increased and there was a positive correlation between potentiation and the FTI. In study 2, we measured maximal potentiation following conditioning contractions (CC) of 25%, 50% and 100% maximal voluntary contraction (MVC) and during a 25% MVC fatigue task, pre-post 8 weeks of muscular endurance training. Results showed significant potentiation for all CC intensities. Potentiation increased as CC intensity increased and CC duration required to achieve maximal potentiation decreased as CC intensity increased. Muscular endurance training resulted in increased maximal potentiation, and potentiation was greater during the fatigue task after training. Potentiation was also correlated to endurance time. In study 3, the effects of muscular endurance training on motor unit firing rates were investigated. There was a small increase in mean motor unit firing rates during the course of the fatigue task after training. This research contributes to our understanding of muscular force production and muscular endurance. The findings suggest that motor unit firing frequency and force potentiation may contribute to enhanced muscular endurance. / text

Tyrimo objektas — vaikų pusiausvyra, raumenų jėga ir ištvermė. Hipotezė: manome, kad vaikų, turinčių autizmo sutrikimą pusiausvyra, raumenų jėga bei ištvermė turėtų būti prastenė nei sveikų vaikų, o 4 savaičių kryptingos kineziterapijos pratybos turėtų reikšmingai pagerinti visus vertintus rodiklius. Tyrimo tikslas — nustatyti kineziterapijos poveikį 7-11 metų vaikų, sergančių autizmu, pusiausvyrai, raumenų jėgai ir raumenų ištvermei. Tyrimo uždaviniai: 1.Nustatyti ir palyginti vaikų, turinčių autizmo sutrikimą ir sveikų vaikų pusiausvyros, raumenų jėgos ir ištvermės rodiklius. 2.Įvertinti 4 savaičių kineziterapijos poveikį vaikų, turinčių autizmo sutrikimą, pusiausvyros, raumenų jėgos ir ištvermės rodikliams. 3.Palyginti vaikų, turinčių autizmo sutrikimą, pusiausvyros, raumenų jėgos ir ištvermės rodiklius, gautus po 4 savaičių intervencijos su sveikų vaikų rodikliais. Rezultatai: Tyrimo rezultatai parodė, kad po kineziterapijos taikymo vaikams, turintiems autizmo sutrikimą pagal modifikuotą Berg skalę, pusiausvyra padidėjo 6 balais. Plaštakos raumenų jėga po kineziterapijos vaikams padidėjo dešinėje rankoje 2 kg, kairėje rankoje 2,2 kg. Šuolio į tolį iš vietos testo rezultatai padidėjo 36,2 cm. Sėstis ir gultis testo rezultatai per 30 sekundžių padidėjo 4,5 karto. Po kineziterapinės intervencijos pritūpimai iki 90° kampo per 30 sekundžių padidėjo 5,7 karto. Lyginant rodiklius prieš kineziterapiją ir po jos, pusiausvyros, raumenų jėgos ir ištvermės rodikliai reikšmingai... [toliau žr. visą tekstą] / Object of the study — children balance, muscle strength and endurance. Hypothesis: We believe that the muscle strength, endurance and balance of children with autism disorder should be worse than the normal healthy children, and that a 4 weeks of targeted physical therapy exercises should significantly improve all evaluated indicators. The aim: determine the effects of physical therapy for children from 7 to 11 years old with the autism of balance, muscular strength and endurance. Goals of the study: 1. To identify and compare balance, muscle strength and endurance characteristics of children with autism disorder and healthy children. 2. To evaluate the effects of 4 weeks physical therapy for the children with autistic disorder of their balance, muscle strength and endurance characteristics. 3. To compare balance, muscle strength and endurance characteristics of children with autistic disorder, after 4 weeks of intervention, with the characteristics of healthy children. Results: The results showed that after physical therapy children with autistic spectrum disorder in accordance with the modified Berg score balance improved by 6 points. Hand muscle strength after physical therapy for children has improved to 2 kg in the right hand and 2.2 kg in the left hand. Standing long jump improved by 36.2 cm. Sit and lie down test results for 30 seconds improved 4.5 times. After physical therapy intervention, the 90° squats for 30 seconds improved 5.7 times. In comparison with the... [to full text]

Tyrimo objektas — vaikų pusiausvyra, raumenų jėga ir ištvermė. Hipotezė: manome, kad vaikų, turinčių autizmo sutrikimą pusiausvyra, raumenų jėga bei ištvermė turėtų būti prastenė nei sveikų vaikų, o 4 savaičių kryptingos kineziterapijos pratybos turėtų reikšmingai pagerinti visus vertintus rodiklius. Tyrimo tikslas — nustatyti kineziterapijos poveikį 7-11 metų vaikų, sergančių autizmu, pusiausvyrai, raumenų jėgai ir raumenų ištvermei. Tyrimo uždaviniai: 1.Nustatyti ir palyginti vaikų, turinčių autizmo sutrikimą ir sveikų vaikų pusiausvyros, raumenų jėgos ir ištvermės rodiklius. 2.Įvertinti 4 savaičių kineziterapijos poveikį vaikų, turinčių autizmo sutrikimą, pusiausvyros, raumenų jėgos ir ištvermės rodikliams. 3.Palyginti vaikų, turinčių autizmo sutrikimą, pusiausvyros, raumenų jėgos ir ištvermės rodiklius, gautus po 4 savaičių intervencijos su sveikų vaikų rodikliais. Rezultatai: Tyrimo rezultatai parodė, kad po kineziterapijos taikymo vaikams, turintiems autizmo sutrikimą pagal modifikuotą Berg skalę, pusiausvyra padidėjo 6 balais. Plaštakos raumenų jėga po kineziterapijos vaikams padidėjo dešinėje rankoje 2 kg, kairėje rankoje 2,2 kg. Šuolio į tolį iš vietos testo rezultatai padidėjo 36,2 cm. Sėstis ir gultis testo rezultatai per 30 sekundžių padidėjo 4,5 karto. Po kineziterapinės intervencijos pritūpimai iki 90° kampo per 30 sekundžių padidėjo 5,7 karto. Lyginant rodiklius prieš kineziterapiją ir po jos, pusiausvyros, raumenų jėgos ir ištvermės rodikliai reikšmingai... [toliau žr. visą tekstą] / Object of the study — children balance, muscle strength and endurance. Hypothesis: We believe that the muscle strength, endurance and balance of children with autism disorder should be worse than the normal healthy children, and that a 4 weeks of targeted physical therapy exercises should significantly improve all evaluated indicators. The aim: determine the effects of physical therapy for children from 7 to 11 years old with the autism of balance, muscular strength and endurance. Goals of the study: 1. To identify and compare balance, muscle strength and endurance characteristics of children with autism disorder and healthy children. 2. To evaluate the effects of 4 weeks physical therapy for the children with autistic disorder of their balance, muscle strength and endurance characteristics. 3. To compare balance, muscle strength and endurance characteristics of children with autistic disorder, after 4 weeks of intervention, with the characteristics of healthy children. Results: The results showed that after physical therapy children with autistic spectrum disorder in accordance with the modified Berg score balance improved by 6 points. Hand muscle strength after physical therapy for children has improved to 2 kg in the right hand and 2.2 kg in the left hand. Standing long jump improved by 36.2 cm. Sit and lie down test results for 30 seconds improved 4.5 times. After physical therapy intervention, the 90° squats for 30 seconds improved 5.7 times. In comparison with the... [to full text]

Tyrimo objektas — vaikų pusiausvyra, raumenų jėga ir ištvermė. Hipotezė: manome, kad vaikų, turinčių autizmo sutrikimą pusiausvyra, raumenų jėga bei ištvermė turėtų būti prastenė nei sveikų vaikų, o 4 savaičių kryptingos kineziterapijos pratybos turėtų reikšmingai pagerinti visus vertintus rodiklius. Tyrimo tikslas — nustatyti kineziterapijos poveikį 7-11 metų vaikų, sergančių autizmu, pusiausvyrai, raumenų jėgai ir raumenų ištvermei. Tyrimo uždaviniai: 1.Nustatyti ir palyginti vaikų, turinčių autizmo sutrikimą ir sveikų vaikų pusiausvyros, raumenų jėgos ir ištvermės rodiklius. 2.Įvertinti 4 savaičių kineziterapijos poveikį vaikų, turinčių autizmo sutrikimą, pusiausvyros, raumenų jėgos ir ištvermės rodikliams. 3.Palyginti vaikų, turinčių autizmo sutrikimą, pusiausvyros, raumenų jėgos ir ištvermės rodiklius, gautus po 4 savaičių intervencijos su sveikų vaikų rodikliais. Rezultatai: Tyrimo rezultatai parodė, kad po kineziterapijos taikymo vaikams, turintiems autizmo sutrikimą pagal modifikuotą Berg skalę, pusiausvyra padidėjo 6 balais. Plaštakos raumenų jėga po kineziterapijos vaikams padidėjo dešinėje rankoje 2 kg, kairėje rankoje 2,2 kg. Šuolio į tolį iš vietos testo rezultatai padidėjo 36,2 cm. Sėstis ir gultis testo rezultatai per 30 sekundžių padidėjo 4,5 karto. Po kineziterapinės intervencijos pritūpimai iki 90° kampo per 30 sekundžių padidėjo 5,7 karto. Lyginant rodiklius prieš kineziterapiją ir po jos, pusiausvyros, raumenų jėgos ir ištvermės rodikliai reikšmingai... [toliau žr. visą tekstą] / Object of the study — children balance, muscle strength and endurance. Hypothesis: We believe that the muscle strength, endurance and balance of children with autism disorder should be worse than the normal healthy children, and that a 4 weeks of targeted physical therapy exercises should significantly improve all evaluated indicators. The aim: determine the effects of physical therapy for children from 7 to 11 years old with the autism of balance, muscular strength and endurance. Goals of the study: 1. To identify and compare balance, muscle strength and endurance characteristics of children with autism disorder and healthy children. 2. To evaluate the effects of 4 weeks physical therapy for the children with autistic disorder of their balance, muscle strength and endurance characteristics. 3. To compare balance, muscle strength and endurance characteristics of children with autistic disorder, after 4 weeks of intervention, with the characteristics of healthy children. Results: The results showed that after physical therapy children with autistic spectrum disorder in accordance with the modified Berg score balance improved by 6 points. Hand muscle strength after physical therapy for children has improved to 2 kg in the right hand and 2.2 kg in the left hand. Standing long jump improved by 36.2 cm. Sit and lie down test results for 30 seconds improved 4.5 times. After physical therapy intervention, the 90° squats for 30 seconds improved 5.7 times. In comparison with the... [to full text]

This study examined the effects of two distinct phases of endurance training (summer and in-season training) in previously well-trained male and female high school cross-country runners. Eleven males and 11 females from the same high school training program were recruited for the three testing sessions: post-track season (June), postsummer training (mid-August), and post-cross-country season (early-November). However, due to injury and other circumstances, only 10 males and 4 females completed all testing sessions. Thus, baseline characteristics were analyzed for both genders; however, longitudinal analysis was only conducted using the males. Submaximal measurements included running economy (RE), blood lactate concentration ([BLa]), and heart rate (HR) at three running speeds in females (6, 7, and 8 mph), and males (7, 8, and 9 mph). Maximal measurements of oxygen uptake (VO2max) and HR, neuromuscular characteristics of isokinetic knee extension strength and vertical jump height, and body composition were also measured. Baseline results showed that the males possessed a higher VO2max, greater neuromuscular characteristics, and lower submaximal [BLa] and HR values than the females. Longitudinal analysis of the males showed that there was an increased VO2max, decreased maximal HR, and decreased neuromuscular strength following summer training. In-season training precipitated further increases in VO2max, an increase in maximal and submaximal HR, and increased neuromuscular characteristics. RE and [BLa] did not significantly change (p<_ 0.05) throughout the course of the study. Likely, it is the subtle changes in these variables in previously welltrained runners which account for the slower performance times at the beginning of the cross-country season and the improvements thereafter. / School of Physical Education

Conversely, AA lost femoral neck BMD over the winter and this was not recovered over the summer, although the increase in width of the femoral neck may have partly compensated BMD loss to maintain strength in bending. The final prospective analysis was conducted in a separate sample of female athletes who were diagnosed with a stress fracture injury. The aim of this analysis was to determine the magnitude and time scale of bone loss following a stress fracture injury and subsequent regain following retaining. A group of 4 stress fracture cases and 3 controls were followed for a period of 6-8 months following a stress fracture injury. BMD and BMC (lumbar spine, femoral neck, and trochanter) and estimations of geometric properties CSA, Z and buckling ratio) were assessed using DXA. The mean difference of bone loss and bone regain was determined by BMD, BMC and geometric parameters from baseline to 6-8 weeks and 6-8 weeks to 6-8 months respectively. No significant bone loss was found in either cases or controls from baseline to 6-8 weeks at any of the bone parameters. A significant difference at the femoral neck was found in the injured leg of the stress fracture cases from 6-8weeks to 6-8months (mean (SE) 1.042(0.102) to 1.070(0.102) g/cm2, p=0.004) with no significant change in the contra-lateral case leg 1.036 (0.102) to 1.054(0.109) g/cm2). No significant bone regain was found in the control subjects (health or injured legs ). Thus athletes do not seem to lose significant BMD during the recovery phase of training when partial weight bearing is required. Subsequent bone regain above the initial baseline value does seem to occur in the injured leg within 8 months following the stress fracture once training is resumed. In conclusion the work within this thesis has not only reinforced previous stress fracture findings, showing that a history of stress fracture is increased in athletes with a history of amenorrhoea, but has identified novel results indicating a lower incidence of stress fracture in female endurance athletes than previously reported. Exercise cognitions have been identified as risk factors for stress fracture history independent of menstrual dysfunction. Furthermore and potentially the most novel finding of this research is the importance for the examination of bone geometric properties in amenorrhoeic athletes. Findings suggest that possible structural adaptations counteract the effects of low BMD and annual losses of BMD during seasonal training in amenorrhoeic endurance athletes. In light of these findings this thesis highlights scope for further longitudinal research in the area of structural adaptation to bone in amenorrhoeic athletes. Keywords: Stress fracture, bone mineral density, bone geometry, endurance athletes, menstrual dysfunction, eating and exercise cognitions.

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