title: Hypohydration does not impair skeletal muscle glycogen resynthesis after exercise.
abstract: The purpose of this investigation was to examine the effects of moderate hypohydration (HY) on skeletal muscle glycogen resynthesis after exhaustive exercise. On two occasions, eight males completed 2 h of intermittent cycle ergometer exercise (4 bouts of 17 min at 60% and 3 min at 80% of maximal O2 consumption/10 min rest) to reduce muscle glycogen concentrations (control values 711 +/- 41 mumol/g dry wt). During one trial, cycle exercise was followed by several hours of light upper body exercise in the heat without fluid replacement to induce HY (-5% body wt); in the second trial, sufficient water was ingested during the upper body exercise and heat exposure to maintain euhydration (EU). In both trials, 400 g of carbohydrate were ingested at the completion of exercise and followed by 15 h of rest while the desired hydration level was maintained. Muscle biopsy samples were obtained from the vastus lateralis immediately after intermittent cycle exercise (T1) and after 15 h of rest (T2). During the HY trial, the muscle water content was lower (P less than 0.05) at T1 and T2 (288 +/- 9 and 265 +/- 5 ml/100 g dry wt, respectively; NS) than during EU (313 +/- 8 and 301 +/- 4 ml/100 g dry wt, respectively; NS). Muscle glycogen concentration was not significantly different during EU and HY at T1 (200 +/- 35 vs. 251 +/- 50 mumol/g dry wt) or T2 (452 +/- 34 vs. 491 +/- 35 mumol/g dry wt). These data indicate that, despite reduced water content during the first 15 h after heavy exercise, skeletal muscle glycogen resynthesis is not impaired.
authors.affiliation: US Army Research Institute of Environmental Medicine, Natick, Massachusetts 01760-5007.
authors.forename: P D
authors.initials: PD
authors.lastname: Neufer
authors.forename: M N
authors.initials: MN
authors.lastname: Sawka
authors.forename: A J
authors.initials: AJ
authors.lastname: Young
authors.forename: M D
authors.initials: MD
authors.lastname: Quigley
authors.forename: W A
authors.initials: WA
authors.lastname: Latzka
authors.forename: L
authors.initials: L
authors.lastname: Levine
mesh_terms: D000293:Adolescent; D000328:Adult; D001834:Body Water / Q000378:metabolism; D003681:Dehydration / Q000378:metabolism*; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D015444:Exercise / Q000502:physiology*; D006003:Glycogen / Q000096:biosynthesis*; D006801:Humans; D008297:Male; D009132:Muscles / Q000378:metabolism*; D010101:Oxygen Consumption; D013546:Sweating / Q000502:physiology
chemical_list: D004040:Dietary Carbohydrates; D006003:Glycogen