Odland, L. M., Alsum A., Spontelli, J., & Schmidt, R. J. (2008). Effect of carbohydrate supplementation on physical, skilled and cognitive performance during a simulated volleyball protocol. ACSM 55th Annual Meeting Indianapolis. Presentation number 854.

This study investigated the effect of ingesting a carbohydrate-electrolyte beverage on exercise performance during simulated volleyball. NCAA DIII volleyball players (N = 10) took part in two counterbalanced exercise sessions where a 6% carbohydrate-electrolyte sports drink, or a flavored placebo was consumed. Ss ingested 20 ml/kg (35.9±4.1 g carbohydrate/hour) before and during exercise. A high-intensity, "stop-and-go" exercise protocol (125 minutes: 10-minutes warm-up, four 23-minute games, four 2½-minute breaks between games, and a 6-minute "game 5") previously designed to closely mimic the physical and skilled demands of a competitive volleyball match was performed. Each "game" included: 27 front and 27 back row rallies, 50 breaks between rallies, and three 47-second time-outs (work:rest = 1:3.3). During rallies, athletes viewed instructions on a screen and performed timed locomotive tasks (shuffling, walking, jogging, sprinting) as well as volleyball specific skills. Each skill performed was scored for accuracy. Also, a timed "hopscotch" performance task was completed once per game. "Game 5" was maximum-intensity and included: serves, 12-m timed shuttles, attacks, block jumps and passes. Cognitive testing (POMS, concentration grid, memory recall) was undertaken between "games".

Blood glucose and lactate were higher in the carbohydrate condition than in the placebo condition. Heart rate and rating of perceived exertion increased in game 5, but were not different between trials. There were no differences between trials for any skilled performance or cognitive tasks. No net change in body weight occurred in either trial, indicating similar sweat rates and ingested fluid volumes. Hopscotch task times and errors improved with carbohydrate supplementation.

Implication. Carbohydrate ingestion increased glucose and lactate, but had had no demonstrable effect on volleyball performance.

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