Nelson, A. G., Davis, G. R., Farney, T. M., Miskowiec, R. W., Trionfante, C. P., & Kokkonen, J. (2013). A pre-exercise dose of melatonin can alter substrate use during exercise. Medicine & Science in Sports & Exercise, 45(5), Supplement abstract number 2394.

This study compared substrate utilization during a 30-minute graded exercise while on either 6 mg melatonin or placebo in college students (M = 12; F = 12). Ss performed stages 1-5 of the Naughton graded-exercise protocol for 30 minutes (in 6-minute stages). Each exercise was performed four times (2 x melatonin, 2 x placebo) at the same time of day with one week separating exercises. During the exercises, expired gases were continually monitored every 30 seconds. Total-, carbohydrate-, and fat-energy expenditures (kJ per ml O2) were obtained from the respiratory exchange ratio using the Lusk procedure. Energy derived (kJ/min) was calculated by multiplying VO2 and the respective energy expenditures. Then, the total-, carbohydrate-, and fat-energies consumed during the 30-minute exercise were determined by calculating the area under the kJ/min: time curve using the trapezoid rule. The final data for the two similar trials were averaged.

Average carbohydrate energy was significantly greater in the melatonin condition than in the placebo condition and accounted for a significantly greater contribution of total energy. Total energy and fat energy were not different between conditions.

Implication. Melatonin ingestion 30 minutes prior to an aerobic exercise increases the amount of carbohydrate used during that exercise. Whether the increased carbohydrate use translates into a performance improvement was not considered in this investigation.

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