Mittleman, K. D., Rangwalla, I., Zacher, C. M., & Bailey, S. P. (1996). Influence of carbohydrate ingestion on exercise to fatigue: Effect of menstrual cycle phase. Medicine and Science in Exercise and Sports, 28(5), Supplement abstract 575.

Elevations in estrogen and progesterone during the luteal phase of the menstrual cycle have been associated with increased lipid metabolism and decreased glycogen utilization. During prolonged exercise, the elevation in plasma free-fatty acids (FFA), which may increase the availability of plasma-free tryptophan to the brain and thus promote "central fatigue" through enhanced serotonin production, is reduced by carbohydrate (CHO) supplementation.

Four women performed exhaustive ergometer cycling tasks on four occasions, two in the follicular phase and two in the luteal phase. A placebo or 6% CHO solution was consumed at 5 ml/kg volume.

The beneficial effects of CHO on performance time, glucose, and FFA concentrations in fatigue were not influenced by the menstrual cycle.

Implication. Menstruation does not affect the beneficial effects of CHO supplementation in exhaustive endurance tasks.

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