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Title: Thermoregulatory Responses during Upper Body Exercise, Thermal Stress, Training and Heat Acclimation
Author: Bottoms, Lindsay
Awarding Body: Coventry University
Current Institution: Coventry University
Date of Award: 2008
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Abstract:
The area of thermoregulation during upper body exercise has received limited research in able bodied individuals. The series of studies presented in this thesis investigated the effect of exercise intensity, duration and environmental temperature on thermoregulatory responses, including calf volume and blood flow, during upper body exercise and recovery. In order to manipulate these variables and observe the adaptive thermoregulatory responses, upper body training and heat acclimation were also performed. Chapter 4 examined the effect of exercise intensity (45, 60, 75· and 90% peak power; Wpeak) on thermoregulatory responses during 5 min of upper body exercise. The results of this study suggest a redistribution of blood from the relatively'inactive lower body during arm exercise of intensities up to 60%Wpeak after which point calf volume did not 'I significantly decrease further. The calf volume decrease is possibly a result of vasoconstriction reducing blood pooling in the leg. Chapter 5 examined the effects of exercise duration (15,30, arid 45 min at 60%Wpeak) on thermoregulatory responses during and after upper body exercise. During upper body exercise at 60% Wpeak calf volume decreased up to 15 min with no further decrease thereafter. In all trials calf blood flow was greater at the cessation of exercise compared to rest suggesting hyperaemia occurred at the end of exercise. Chapter ~ examined the effects of exercise (30 min, 60%Wpeak) in different environmental temperatures (21, 27 ~nd 33°C) on thermoregulatory responses. Calf skin blood flow from Laser Doppler measurements increased in all trials with a concomitant decrease in calf volume. The decrease in the calf volume..reported therefore reflected a greater and more substantial muscle vasoconstriction compared to increased skin blood flow. There was a greater decrease in calf volume during the 27°C trial which appears to be, a result of a lower skin blood flow response compared to exercising in 33°C. Chapter 7 examined the effect of 8 weeks of upper body training on thermoregulatory responses during upper body exercise. Upper body training reduced aural temperature and heat storage at a given power output as a result of increased whole body sweating and heat flow. Upper body training produced a smaller calf volume change after training at the same absolute exercise intensity demonstrating less leg vasoconstriction which was possibly as a result of a reduced response to sympathetic nervous activity or the fact that exercise was performed overall at a lower intensity post training (47% vs. 60%Wpeak). Chapter 8 examined the effect cSf exercising (30 min, 60%Wpeak) evrpry day in the h~at for 7 . '. days on'thermoregulatory responses to upper body exercise in the heat. There was reduced core temperature during exercise. The calf volume decrease was significantly greater during exercise in the heat following heat acclimation which may be a .result of increased vasoconstriction compensating, for an increase in skin blood flow to reduce venous pooling and therefore to maintain both stroke volume and blood flow to the skin. The lower body appears to have an important role in both cardiovascular stability as well as thermoregulation during upper body exercise.. It is proposed that this is achieved by reducing venous pooling in the calf thus increasing the availability of blood for maintaining stroke volume and increasing skin blood flow during exercise. The responses at the calf during exercise can be adapted through heat acclimation and upper body training.
Supervisor: Not available Sponsor: Not available
Qualification Name: Coventry University, 2008 Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.487373  DOI: Not available
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