Bailey, S. P., Fredde, C., Sonnycalb, A., & Szabo, M. (2008). Effects of carbohydrate supplementation on changes in cognitive function during prolonged exercise in the heat. ACSM 55th Annual Meeting Indianapolis, Presentation Number 2422.

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This study determined if cognitive function is influenced by exercise in the heat and carbohydrate supplementation. Males (N = 8) completed four exercise trials to volitional fatigue. During each trial, Ss cycled at 60% of ventilatory threshold in a normal (~22C) or hot (~35) environment. Every 30 minutes during exercise, Ss drank 5 ml/kgBW of either a 6% carbohydrate beverage or a water placebo indistinguishable in color and taste. Ss completed a cognitive assessment battery before, after one hour of exercise, and immediately after fatigue. The cognitive assessment battery included tests assessing grammatical reasoning, code substitution, math processing, and tapping.

Grammatical reasoning was worse in the heat. Math processing was affected by both drink and environmental conditions, being better with carbohydrate supplementation and worse in the heat. Code substitution was similarly affected by both the drink and environmental conditions. Reaction time in grammatical reasoning was faster at fatigue during the normal-carbohydrate condition than in the normal-placebo condition, however, there were no differences in the heat. Similar findings occurred with reaction time at fatigue in math processing. No differences were observed in reaction time in code substitution or tapping for any measure.

Implication. Cognitive function is negatively influenced by prolonged exercise in the heat. Carbohydrate supplementation lessens some of those effects.

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