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Title: Physiological consequences of altering the method of dehydration and rehydration in man
Author: Archer, David Thomas
ISNI:       0000 0004 2732 4320
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2012
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Hypohydration occurs voluntarily and involuntarily in exercising and occupational situations, thus replacement of fluid losses is essential to optimise recovery. The experiments in the present thesis have confirmed and extended previous research concerning the effects of different methods of moderate body water losses on exercise capacity and post-dehydration recovery of fluid deficits. It was confirmed that sweat sodium concentration, determined by a whole body wash- down technique, decreased during 7 consecutive days of exercise in the heat, though increased sweat rates resulted in identical daily sweat sodium losses over the 7 days. Fluid restriction over a 37h period induced an average 2.7% body mass loss, resulting in significant hypovolaemia and hypertonicity. Hypohydration was associated with increased reported thirst, tiredness, head soreness and impaired alertness and concentration. Evidence from the present thesis found that high intensity aerobic exercise capacity in a temperate environment is reduced by moderate hypohydration. Furthermore, hypohydration induced by combined exercise and fluid restriction reduced exercise capacity to a greater extent than fluid restriction alone. Body mass losses incurred by either 24h fluid restriction or combined fluid restriction/exercise resulted in 2% of body mass loss. Subsequent rehydration resulted in identical urine volumes being produced, drink retention and hence overall net fluid balance on both trials. Rapid recovery of fluid losses is recommended following hypohydration to re- establish exercise capacity. However present results suggest that this may have negative consequences for retention of a carbohydrate-electrolyte solution as a consequence of greater hypotonicity and hypervolaemia. Milk has been shown to be an effective fluid for post exercise rehydration and is a convenient means for creatine delivery. Ingestion of a milk based creatine containing drink was found to have a negative influence on recovery of fluid following exercise compared with a placebo, yet was seen to result in improved capacity for endurance exercise.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available