title: Effect of various carbohydrate-electrolyte fluids on cycling performance and maximal voluntary contraction.
abstract: The purpose of this study was to compare the effects of a carbohydrate-electrolyte plus caffeine, carnitine, taurine, and B vitamins solution (CE+) and a carbohydrate-electrolyte-only solution (CE) vs. a placebo solution (PLA) on cycling performance and maximal voluntary contraction (MVC). In a randomized, double-blind, crossover, repeated-measures design, 14 male cyclists (M +/- SD age 27 +/- 6 yr, VO2max 60.4 +/- 6.8 ml x kg-1 x min(-1)) cycled for 120 min submaximally (alternating 61% +/- 5% and 75% +/- 5% VO2max) and then completed a 15-min performance trial (PT). Participants ingested CE+, CE, or PLA before (6 ml/kg) and every 15 min during exercise (3 ml/kg). MVC was measured as a single-leg isometric extension (70 degree knee flexion) before (pre) and after (post) exercise. Rating of perceived exertion (RPE) was measured throughout. Total work accumulated (KJ) during PT was greater (p < .05) in CE+ (233 +/- 34) than PLA (205 +/- 52) but not in CE (225 +/- 39) vs. PLA. MVC (N) declined (p < .001) from pre to post in PLA (988 +/- 213 to 851 +/- 191) and CE (970 +/- 172 to 870 +/- 163) but not in CE+ (953 +/- 171 to 904 +/- 208). At Minutes 60, 90, 105, and 120 RPE was lower in CE+ (14 +/- 2, 14 +/- 2, 12 +/- 1, 15 +/- 2) than in PLA (14 +/- 2, 15 +/- 2, 14 +/- 2, 16 +/- 2; p < .001). CE+ resulted in greater total work than PLA. CE+, but not PLA or CE, attenuated pre-to-post MVC declines. Performance increases during CE+ may have been influenced by lower RPE and greater preservation of leg strength during exercise in part as a result of the hypothesized effects of CE+ on the central nervous system and skeletal muscle.
authors.affiliation: Human Performance Laboratory, University of Connecticut, Storrs, CT, USA.
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Ganio
authors.forename: Jennifer F
authors.initials: JF
authors.lastname: Klau
authors.forename: Elaine C
authors.initials: EC
authors.lastname: Lee
authors.forename: Susan W
authors.initials: SW
authors.lastname: Yeargin
authors.forename: Brendon P
authors.initials: BP
authors.lastname: McDermott
authors.forename: Maxime
authors.initials: M
authors.lastname: Buyckx
authors.forename: Carl M
authors.initials: CM
authors.lastname: Maresh
authors.forename: Lawrence E
authors.initials: LE
authors.lastname: Armstrong
mesh_terms: D000328:Adult; D054874:Athletic Performance; D001642:Bicycling / Q000502:physiology*; D002110:Caffeine / Q000008:administration & dosage; D002331:Carnitine / Q000008:administration & dosage; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000494:pharmacology; D004311:Double-Blind Method; D004573:Electrolytes / Q000008:administration & dosage* / Q000494:pharmacology; D006801:Humans; D007537:Isometric Contraction / Q000187:drug effects / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D015532:Rehydration Solutions / Q000008:administration & dosage* / Q000494:pharmacology; D013647:Task Performance and Analysis; D013654:Taurine / Q000008:administration & dosage; D014803:Vitamin B Complex / Q000009:adverse effects; D014882:Water-Electrolyte Balance / Q000502:physiology
chemical_list: D004040:Dietary Carbohydrates; D004573:Electrolytes; D015532:Rehydration Solutions; D014803:Vitamin B Complex; D013654:Taurine; D002110:Caffeine; D002331:Carnitine