We examined the recovery of plasma volume, plasma osmolality, renal water and
sodium handling and fluid-regulating
hormones to dehydrating exercise in well-trained women and compared them to men. Ten male and eight female athletes cycled at anaerobic threshold at an ambient temperature of 32 degrees C until
dehydration by 3% of their body mass (mb). After exercise, they drank water equal to 1% mb and rested for 240 min. Plasma
renin activity (PRA), serum
aldosterone [ALDO]s, plasma
arginine vasopressin [AVP]pl,
norepinephrine concentrations and plasma osmolality (Osmpl) were determined at baseline, end of exercise, 30, 60, 120 and 240 min postexercise. Urine was collected at baseline, end of exercise, 60, 120 and 240 min postexercise. Renal free water and
sodium handling were assessed. The recovery of OSMpl and plasma volume occurred within the first 60 min of recovery and at similar rates between the groups. However, women had lower PRA at the end of exercise (P = 0.05), an earlier recovery of [ALDO]s, and a slower [AVP]pl recovery. Overall fluid balance was similar between the men and women, as were the early recovery of renal free water clearance (CH2O). During the last 120 min of recovery CH2O was more negative (greater water reabsorption) and fractional
sodium excretion was increased in the women compared to the men. Despite small differences in
sodium and water reabsorption following
dehydration, it appears from other study that recovery from dehydrating exercise in well-trained men and women is remarkably similar.