The influence of a 12% carbohydrate-electrolyte beverage on self-paced soccer-specific exercise performance

Objectives: To assess the physiological and performance effects of a 12% carbohydrate-electrolyte beverage consumed at practically applicable time-points (i.e., before each half) throughout simulated soccer match-play.Design: Randomised, crossover.Methods: Fed players (n=15) performed 90-min of soccer-specific exercise (including self-paced exercise at the end of each half). Players consumed carbohydrate-electrolyte (CHO; 60 g·500 ml-1, Na+ 205 mg·500 ml-1), placebo-electrolyte (PL) or water (Wat) beverages at the end of the warm-up (250 ml) and half-time (250 ml plus ad-libitum water). Blood was drawn before each half and every 15-min during exercise. Physical (15-m sprinting, countermovement jumps, self-paced distance, acceleration/deceleration count), technical (dribbling) and cognitive (memory, attention, decision-making) performance was assessed. Ratings of perceived exertion (RPE) and abdominal discomfort were measured.Results: Against Wat and PL, CHO increased (all p<0.05) mean accelerations >1.5 m·s-2 during self-paced exercise (>+25%) and dribbling speed from 60-min onwards (>+3%). Mean sprinting speed improved (+2.7%) in CHO versus Wat. Blood glucose increased before and during each half in CHO versus PL and Wat (all p<0.05). A 27% decline in glycaemia occurred at 60-min in CHO. RPE was comparable between trials. Cognition reduced post-exercise (p<0.05); this decline was not attenuated by CHO. Abdominal discomfort increased during exercise but was similar between trials.Conclusions: Using more realistic fluid ingestion timings than have been examined previously, consuming a 12% carbohydrate-electrolyte beverage increased blood glucose, self-paced exercise performance, and improved dribbling speed in the final 30-min of exercise compared to water and placebo. Carbohydrates did not attenuate post-exercise reductions in cognition.