Ana Carolina Vimieiro-Gomes

Hidratação durante o exercício: a sede é suficiente?

The present work proposes a review about exercise fluid replacement and a discussion whether, during exercise, the fluid ingested according to thirst is sufficient to maintain hydration. Exercise sweat loss, mainly in the heat, can cause dehydration, can alter the hidroelectrolyte balance, disturb thermoregulation, presenting a health risk and/or impairing the athletic performance. It has been asserted that athletes do not drink, spontaneously, the sufficient fluid volume to prevent dehydration during the physical activity. Thus, international recommendations to fluid replacement during physical activities have been proposed. According to the American College of Sports Medicine (ACSM), about 500 mL of fluid on the two hours before the exercise must be ingested. During exercise, they propose that athletes should start fluid replacement since the beginning in regular periods and should drink enough fluid to restore all the sweating losses or ingest the maximal volume tolerated. The National Athletic Trainer’s Association (NATA) proposes the following recommendations: ingestion of 500 to 600 mL of water two or three hours before exercise or other sport drink and ingestion of 200 to 300 mL 10 to 20 minutes before exercise starting. During exercise, the fluid replacement should match the sweating and urine losses and at least should maintain hydration status reaching maximal body weight losses of 2%. After the exercise, fluid replacement must restore all the fluid losses accumulated. In addition, ACSM and NATA asserted about fluid temperature and palatability, beverage carbohydrate and electrolyte additions according to exercise duration and intensity and recommended hydration schedules to provide easier access to fluid ingestion. However, other authors contest the use of hydration schedules based on predetermined fluid volumes and suggest that fluid replacement according to thirst is enough to maintain body homeostasis.ABSTRACTExercise fluid replacement: is thirst enough? The present work proposes a review about exercise fluid repla-cement and a discussion whether, during exercise, the fluid in-gested according to thirst is sufficient to maintain hydration. Exer-cise sweat loss, mainly in the heat, can cause dehydration, canalter the hidroelectrolyte balance, disturb thermoregulation, pre-senting a health risk and/or impairing the athletic performance. Ithas been asserted that athletes do not drink, spontaneously, thesufficient fluid volume to prevent dehydration during the physicalactivity. Thus, international recommendations to fluid replacementduring physical activities have been proposed. According to theAmerican College of Sports Medicine (ACSM), about 500 mL offluid on the two hours before the exercise must be ingested. Dur-ing exercise, they propose that athletes should start fluid replace-ment since the beginning in regular periods and should drinkenough fluid to restore all the sweating losses or ingest the max-imal volume tolerated. The National Athletic Trainer’s Association(NATA) proposes the following recommendations: ingestion of 500to 600 mL of water two or three hours before exercise or othersport drink and ingestion of 200 to 300 mL 10 to 20 minutes be-fore exercise starting. During exercise, the fluid replacement shouldmatch the sweating and urine losses and at least should maintainhydration status reaching maximal body weight losses of 2%. Af-ter the exercise, fluid replacement must restore all the fluid loss-es accumulated. In addition, ACSM and NATA asserted about fluidtemperature and palatability, beverage carbohydrate and electro-lyte additions according to exercise duration and intensity and rec-ommended hydration schedules to provide easier access to fluidingestion. However, other authors contest the use of hydrationschedules based on predetermined fluid volumes and suggest thatfluid replacement according to thirst is enough to maintain bodyhomeostasis.

Comparison of sweat rate during graded exercise and the local rate induced by pilocarpine

Centrally stimulated sweat rate produced by graded exercise until exhaustion was compared to the local sweat rate induced by pilocarpine, often used as a sweating index for healthy individuals. Nine young male volunteers (22 +/- 4 years) were studied in temperate environment in two situations: at rest and during progressive exercise with 25 W increases every 2 min until exhaustion, on a cycle ergometer. In both situations, sweating was induced on the right forearm with 5 ml 0.5% pilocarpine hydrochloride applied by iontophoresis (1.5 mA, 5 min), with left forearm used as control. Local sweat rate was measured for 15 min at rest. During exercise, whole-body sweat rate was calculated from the body weight variation. Local sweat rate was measured from the time when heart rate reached 150 bpm until exhaustion and was collected using absorbent filter paper. Pharmacologically induced local sweat rate at rest (0.4 +/- 0.2 mg cm-2 min-1) and mean exercise-induced whole-body sweat rate (0.4 +/- 0.1 mg cm-2 min-1) were the same (P > 0.05) but were about five times smaller than local exercise-induced sweat rate (control = 2.1 +/- 1.4; pilocarpine = 2.7 +/- 1.2 mg cm-2 min-1), indicating different sudorific mechanisms. Both exercise-induced whole-body sweat rate (P < 0.05) and local sweat rate (P < 0.05) on control forearm correlated positively with pilocarpine-induced local sweat rate at rest. Assuming that exercise-induced sweating was a result of integrated physiological mechanisms, we suggest that local and whole-body sweat rate measured during graded exercise could be a better sweating index than pilocarpine.

Hidratación durante el ejercicio: ¿la sed es suficiente?

The present work proposes a review about exercise fluid replacement and a discussion whether, during exercise, the fluid ingested according to thirst is sufficient to maintain hydration. Exercise sweat loss, mainly in the heat, can cause dehydration, can alter the hidroelectrolyte balance, disturb thermoregulation, presenting a health risk and/or impairing the athletic performance. It has been asserted that athletes do not drink, spontaneously, the sufficient fluid volume to prevent dehydration during the physical activity. Thus, international recommendations to fluid replacement during physical activities have been proposed. According to the American College of Sports Medicine (ACSM), about 500 mL of fluid on the two hours before the exercise must be ingested. During exercise, they propose that athletes should start fluid replacement since the beginning in regular periods and should drink enough fluid to restore all the sweating losses or ingest the maximal volume tolerated. The National Athletic Trainer’s Association (NATA) proposes the following recommendations: ingestion of 500 to 600 mL of water two or three hours before exercise or other sport drink and ingestion of 200 to 300 mL 10 to 20 minutes before exercise starting. During exercise, the fluid replacement should match the sweating and urine losses and at least should maintain hydration status reaching maximal body weight losses of 2%. After the exercise, fluid replacement must restore all the fluid losses accumulated. In addition, ACSM and NATA asserted about fluid temperature and palatability, beverage carbohydrate and electrolyte additions according to exercise duration and intensity and recommended hydration schedules to provide easier access to fluid ingestion. However, other authors contest the use of hydration schedules based on predetermined fluid volumes and suggest that fluid replacement according to thirst is enough to maintain body homeostasis.ABSTRACTExercise fluid replacement: is thirst enough? The present work proposes a review about exercise fluid repla-cement and a discussion whether, during exercise, the fluid in-gested according to thirst is sufficient to maintain hydration. Exer-cise sweat loss, mainly in the heat, can cause dehydration, canalter the hidroelectrolyte balance, disturb thermoregulation, pre-senting a health risk and/or impairing the athletic performance. Ithas been asserted that athletes do not drink, spontaneously, thesufficient fluid volume to prevent dehydration during the physicalactivity. Thus, international recommendations to fluid replacementduring physical activities have been proposed. According to theAmerican College of Sports Medicine (ACSM), about 500 mL offluid on the two hours before the exercise must be ingested. Dur-ing exercise, they propose that athletes should start fluid replace-ment since the beginning in regular periods and should drinkenough fluid to restore all the sweating losses or ingest the max-imal volume tolerated. The National Athletic Trainer’s Association(NATA) proposes the following recommendations: ingestion of 500to 600 mL of water two or three hours before exercise or othersport drink and ingestion of 200 to 300 mL 10 to 20 minutes be-fore exercise starting. During exercise, the fluid replacement shouldmatch the sweating and urine losses and at least should maintainhydration status reaching maximal body weight losses of 2%. Af-ter the exercise, fluid replacement must restore all the fluid loss-es accumulated. In addition, ACSM and NATA asserted about fluidtemperature and palatability, beverage carbohydrate and electro-lyte additions according to exercise duration and intensity and rec-ommended hydration schedules to provide easier access to fluidingestion. However, other authors contest the use of hydrationschedules based on predetermined fluid volumes and suggest thatfluid replacement according to thirst is enough to maintain bodyhomeostasis.

Exercise fluid replacement: is thirst enough?

The present work proposes a review about exercise fluid replacement and a discussion whether, during exercise, the fluid ingested according to thirst is sufficient to maintain hydration. Exercise sweat loss, mainly in the heat, can cause dehydration, can alter the hidroelectrolyte balance, disturb thermoregulation, presenting a health risk and/or impairing the athletic performance. It has been asserted that athletes do not drink, spontaneously, the sufficient fluid volume to prevent dehydration during the physical activity. Thus, international recommendations to fluid replacement during physical activities have been proposed. According to the American College of Sports Medicine (ACSM), about 500 mL of fluid on the two hours before the exercise must be ingested. During exercise, they propose that athletes should start fluid replacement since the beginning in regular periods and should drink enough fluid to restore all the sweating losses or ingest the maximal volume tolerated. The National Athletic Trainer’s Association (NATA) proposes the following recommendations: ingestion of 500 to 600 mL of water two or three hours before exercise or other sport drink and ingestion of 200 to 300 mL 10 to 20 minutes before exercise starting. During exercise, the fluid replacement should match the sweating and urine losses and at least should maintain hydration status reaching maximal body weight losses of 2%. After the exercise, fluid replacement must restore all the fluid losses accumulated. In addition, ACSM and NATA asserted about fluid temperature and palatability, beverage carbohydrate and electrolyte additions according to exercise duration and intensity and recommended hydration schedules to provide easier access to fluid ingestion. However, other authors contest the use of hydration schedules based on predetermined fluid volumes and suggest that fluid replacement according to thirst is enough to maintain body homeostasis.ABSTRACTExercise fluid replacement: is thirst enough? The present work proposes a review about exercise fluid repla-cement and a discussion whether, during exercise, the fluid in-gested according to thirst is sufficient to maintain hydration. Exer-cise sweat loss, mainly in the heat, can cause dehydration, canalter the hidroelectrolyte balance, disturb thermoregulation, pre-senting a health risk and/or impairing the athletic performance. Ithas been asserted that athletes do not drink, spontaneously, thesufficient fluid volume to prevent dehydration during the physicalactivity. Thus, international recommendations to fluid replacementduring physical activities have been proposed. According to theAmerican College of Sports Medicine (ACSM), about 500 mL offluid on the two hours before the exercise must be ingested. Dur-ing exercise, they propose that athletes should start fluid replace-ment since the beginning in regular periods and should drinkenough fluid to restore all the sweating losses or ingest the max-imal volume tolerated. The National Athletic Trainer’s Association(NATA) proposes the following recommendations: ingestion of 500to 600 mL of water two or three hours before exercise or othersport drink and ingestion of 200 to 300 mL 10 to 20 minutes be-fore exercise starting. During exercise, the fluid replacement shouldmatch the sweating and urine losses and at least should maintainhydration status reaching maximal body weight losses of 2%. Af-ter the exercise, fluid replacement must restore all the fluid loss-es accumulated. In addition, ACSM and NATA asserted about fluidtemperature and palatability, beverage carbohydrate and electro-lyte additions according to exercise duration and intensity and rec-ommended hydration schedules to provide easier access to fluidingestion. However, other authors contest the use of hydrationschedules based on predetermined fluid volumes and suggest thatfluid replacement according to thirst is enough to maintain bodyhomeostasis.