Rehydration with drinks differing in sodium concentration and recovery from moderate exercise-induced hypohydration in man.
To investigate how differing moderate sodium chloride concentrations affect rehydration after exercise and subsequent exercise capacity, eight males lost 1.98 +/- 0.1% body mass exercising in the heat, then consumed one of four drinks in a volume equivalent to 150% of mass loss. Drinks were identical except for sodium chloride content (1 +/- 1, 31 +/- 1, 40 +/- 1, 50 +/- 1 mmol/l). After 4 h recovery subjects cycled for 5 min at 70% VO(2peak) then at 95% VO(2peak) until volitional fatigue. Urine output was inversely related to sodium intake: more was produced with the 1 than the 40 and 50 mmol/l drinks (P < 0.01). Time to exhaustion in the exercise capacity test was not different between treatments (P = 0.883). The addition of 40 or 50 mmol/l of sodium chloride to a rehydration beverage reduced subsequent urine output, thereby providing more effective rehydration than a sodium-free drink. This did not, however, result in improved performance 4 h after the end of the rehydration period.
Merson
Stuart J
SJ
School of Sport and Exercise Sciences, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK.
Maughan
Ronald J
RJ
Shirreffs
Susan M
SM
D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology; D001628:Beverages / Q000032:analysis*; D001642:Bicycling / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D002712:Chlorides / Q000032:analysis / Q000494:pharmacology; D003681:Dehydration / Q000378:metabolism*; D004573:Electrolytes / Q000097:blood / Q000652:urine; D015444:Exercise / Q000502:physiology*; D005440:Fluid Therapy / Q000379:methods*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D009994:Osmolar Concentration; D011188:Potassium / Q000032:analysis / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology*; D014882:Water-Electrolyte Balance / Q000502:physiology
D002712:Chlorides; D004573:Electrolytes; D012964:Sodium; D011188:Potassium