title: Water and carbohydrate ingestion during prolonged exercise increase maximal neuromuscular power.
abstract: This study investigated the individual and combined effects of water and carbohydrate ingestion during prolonged cycling on maximal neuromuscular power (P(max)), thermoregulation, cardiovascular function, and metabolism. Eight endurance-trained cyclists exercised for 122 min at 62% maximal oxygen uptake in a 35 degrees C environment (50% relative humidity, 2 m/s fan speed). P(max) was measured in triplicate during 6-min periods beginning at 26, 56, 86, and 116 min. On four different occasions, immediately before and during exercise, subjects ingested 1) 3.28 +/- 0.21 liters of water with no carbohydrate (W); 2) 3.39 +/- 0.23 liters of a solution containing 204 +/- 14 g of carbohydrate (W+C); 3) 204 +/- 14 g of carbohydrate in only 0.49 +/- 0.03 liter of solution (C); and 4) 0. 37 +/- 0.02 liter of water with no carbohydrate (placebo; Pl). These treatments were randomized, disguised, and presented double blind. At 26 min of exercise, P(max) was similar in all trials. From 26 to 116 min, P(max) declined 15.2 +/- 3.3 and 14.5 +/- 2.1% during C and Pl, respectively; 10.4 +/- 1.9% during W (W > C, W > Pl; P < 0.05); and 7.4 +/- 2.2% during W+C (W+C > W, W+C > C, and W+C > Pl; P < 0. 05). As an interesting secondary findings, we also observed that carbohydrate ingestion increased heat production, final core temperature, and whole body sweating rate. We conclude that, during prolonged moderate-intensity exercise in a warm environment, ingestion of W attenuates the decline in P(max). Furthermore, ingestion of W+C attenuates the decline in maximal power more than does W alone, and ingestion of C alone does not attenuate the decline in P(max) compared with Pl.
authors.affiliation: Human Performance Laboratory, The University of Texas at Austin, Austin, Texas 78712, USA.
authors.forename: R G
authors.initials: RG
authors.lastname: Fritzsche
authors.forename: T W
authors.initials: TW
authors.lastname: Switzer
authors.forename: B J
authors.initials: BJ
authors.lastname: Hodgkinson
authors.forename: S H
authors.initials: SH
authors.lastname: Lee
authors.forename: J C
authors.initials: JC
authors.lastname: Martin
authors.forename: E F
authors.initials: EF
authors.lastname: Coyle
mesh_terms: D000284:Administration, Oral; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D001810:Blood Volume / Q000187:drug effects; D015992:Body Mass Index; D001831:Body Temperature / Q000187:drug effects; D050260:Carbohydrate Metabolism; D002241:Carbohydrates / Q000008:administration & dosage / Q000494:pharmacology*; D002395:Catecholamines / Q000097:blood; D004573:Electrolytes / Q000097:blood; D015444:Exercise / Q000502:physiology*; D005223:Fats / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007328:Insulin / Q000097:blood; D007773:Lactates / Q000097:blood; D008297:Male; D009469:Neuromuscular Junction / Q000187:drug effects / Q000502:physiology; D009994:Osmolar Concentration; D010084:Oxidation-Reduction / Q000187:drug effects; D010101:Oxygen Consumption / Q000187:drug effects; D010807:Physical Endurance / Q000187:drug effects* / Q000502:physiology; D005082:Physical Exertion / Q000187:drug effects; D012039:Regional Blood Flow / Q000187:drug effects; D012867:Skin / Q000098:blood supply; D013546:Sweating / Q000187:drug effects; D013997:Time Factors; D014867:Water / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D001786:Blood Glucose; D002241:Carbohydrates; D002395:Catecholamines; D004573:Electrolytes; D005223:Fats; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D007773:Lactates; D014867:Water; D005990:Glycerol