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, VO 2max 60.4 ± 6.8 ml · kg -1 · min -1 ) cycled for 120 min submaximally (alternating 61% ± 5% and 75% ± 5% VO 2max ) 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° 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.

Caffeine does not alter RPE or pain perception during intense exercise in active women

“…Doherty and Smith (2005) reported that caffeine reduces rating of perceived exertion (RPE) during exercise which explained approximately 30% of increased performance in response to caffeine ingestion. Supporting this result are recent studies (Cureton et al, 2007;Ganio et al, 2010) showing caffeine-mediated reductions in RPE during 2 h of submaximal cycling as well as improved performance during a subsequent 15 min time trial. However, existing literature suggests that RPE is not attenuated at the end of exhaustive exercise, as caffeine seems not to alter performance at intensities approaching maximum (Dodd, Brooks, & Powers, 1991;Powers, Byrd, Tulley, & Callender, 1983).…”

National Athletic Trainers' Association Position Statement: Fluid Replacement for the Physically Active

“…80,202,229,230 Competitive athletes can benefit from carbohydrate-electrolyte beverages before activity. 82,116,222,224 Physically active people eating a balanced diet with adequate calories and fluids need not add ingredients to water to maintain hydration status. Beverages that appeal to individual taste preferences may encourage individuals to drink more fluids.…”

“…116,118,119,121 Small amounts of caffeine in a rehydration beverage should not cause harm to the physically active postexercise.…”

Accumulation of 2H2O in plasma and eccrine sweat during exercise-heat stress

“…The following methods and results were collected as part of a larger double-blind, randomized, crossover study which compared two carbohydrate-electrolyte drinks versus placebo (i.e., the water solution used in the present study); this larger study focused on prolonged cycling performance and knee extensor maximal voluntary contraction (Ganio et al 2009). Only the methods and results directly relating to the placebo condition are reported here.…”