Abstract
Abstract Eight healthy men, unacclimated to heat, were submitted to variations in body hydration. The subjects were kept euhydrated, dehydrated by controlled passive hyperthermia or exercise on a treadmill up to a weight loss of 2.8%, or hyperhydrated using a solution containing glycerol, with a total ingested volume equal to 21.4 ml/kg of body weight. On completion of a 90-min recovery period, the subjects were assigned a pedaling exercise on an arm-crank ergometer. Psychological tests were administered 30 min after the phase of hydration variation and 15 min after the arm crank exercise. Both dehydration conditions impaired cognitive abilities (i.e., perceptive discrimination, psycho-motor skills, and short-term memory) as well as subjective estimates of fatigue, without any relevant differences between them. Short-term memory was significantly greater following hyperhydration when compared to euhydration (P < .05). Following arm crank exercise, further effects of dehydration were found for tracking performance only (P < .05). Moreover, long-term memory was impaired in both control and dehydration situations, whereas there was no decrement in performance in the hyperhydration condition.
References
Buskirk, E.R. , Iampietro, P.E. , Bass, D.E. (1959). Work performance after dehydration: Effects of physical conditioning and acclimatization. Journal of Applied Physiology, 12, 189– 194 .Francesconi, R.P. , Sawka, M.N. , Hubbard, R.W. , Pandolf, K.B. (1989). Hormonal regulation of fluid and electrolytes: effects of heat exposure and exercise in the heat. In J.R. Claybaugh & C.E. Wade (Eds.), Hormonal regulation of fluid and electrolytes (pp. 45-85). New York and London: Plenum Press .Gliner, J.A. , Matsen-Twisdale, J.A. , Horvath, S.M. , Maron, M.B. (1979). Visual evoked potentials and signal detection following a marathon race. Medicine and Science in Sports, 11, 155– 159 .Gutin, B. (1966). Effects of increase in physical fitness on mental ability following physical and mental stress. Research Quarterly, 37, 211– 220 .Gopinathan, P.M. , Pichan, G. , Sharma, M.A. (1988). Role of dehydration in heat stress-induced variations in mental performance. Archives of Environmental Health, 43, 15– 17 .Hogervorst, E. , Riedel, W. , Jeukendrup, A. , Jolles, J. (1996). Cognitive performance after strenuous physical exercise. Perceptual and Motor Skills, 83, 479– 488 .Horstman, D.H. , Horvath, S.M. (1972). Cardiovascular and temperature regulatory changes during progressive dehydration and euhydration. Journal of Applied Physiology, 33, 446– 450 .Joseph, N.T. , Santa Joseph , Bhatti, J. , Parihar, M.S. (1976). Effect of dehydration (Hypohydration) on physical work capacity. Indian Journal of Physiology and Allied Sciences, 30, 145– 151 .Kozlowski, S. , Saltin, B. (1994). Effects of sweat loss on body fluids. Journal of Applied Physiology, 69, 1119– 1124 .Ladell, W.S.S. (1965). Water and salt (sodium chloride intake). In O.G. Edholm & A.L. Bacharach (Eds.), Physiology of human survival. New York: Academic Press .Lybrand, W. , Andrews, T. , Ross, S. (1954). Systematic fatigue and perceptual organization. American Journal of Psychology, 67, 704– 707 .Lyons, T.P. , Riedsel, M.L. , Meuli, L.E. , Chick, T.W. (1990). Effects of glycerol-induced hyperhydration prior to exercise in the heat on sweating and core temperature. Medicine and Science in Sports and Exercise, 22, 477– 483 .Pepler, R.D. (1958). Warmth and performance. An investigation in the tropics. Ergonomics, 2, 63– .Piwonka, R.W. , Robinson, S. (1967). Acclimatization of highly trained men in severe heat. Journal of Applied Physiology, 22, 9– 12 .Sargent, F. , Brown, W.K. , Pessa, A.T. , Waligora, J. , Weinman, K.P. (1964). Observations on dehydration and eccrine sweating. Arid zone research XXIV, Environmental physiology and psychology in arid conditions, 115– 119 .Sharma, V.M. , Sridharan, K. , Pichan, G. , Panwar, M.R. (1986). Influence of heat-stress induced dehydration on mental functions. Ergonomics, 29, 791– 799 .Tomporowsky, P.D. , Ellis, R.N. (1986). Effects of exercise on cognitive processes: A review. Psychological Bulletin, 99, 338– 346 .Tourtelotte, W.W. , Reinglass, J.L. , Newkirk, T.A. (1972). Cerebral dehydration action of glycerol. Clinical Pharmacology & Therapeutics, 13, 159– 171 .Wade, C.E. , Freund, B.J. , Claybaugh, J.R. (1989). Fluid and electrolyte homeostasis during and following exercise: hormonal and non-hormonal factors. In J.R. Claybaugh & C.E. Wade (Eds.), Hormonal regulation of fluid and electrolytes (pp. 1-44). New York and London: Plenum Press .Weingarten, G. (1973). Mental performance during physical exertion: The benefit of being physically fit. International Journal of Sport Psychology, 4, 16– 26 .Wing, J.F. (1965). Upper thermal tolerance limits for unimpaired mental performance. Aerospace Medicine, 36, 960– 964 .
