In 12 recreationally trained women, a carbohydrate drink during 90 min of heavy cycling made a following 4-km time trial faster than placebo to a similar degree in the mid-follicular and mid-luteal phases (9.9 and 9.8 min vs 10.4 and 10.0 min), and performance and performance fatigability did not differ between the two phases (one small crossover, read from its abstract)

Fleitas-Paniagua and colleagues (the Murias laboratory) asked whether a carbohydrate drink during heavy cycling helps a later time trial equally across two menstrual cycle phases, and whether the phase changes perceived or muscle fatigue.

Twelve recreationally trained women rode 90 min at a constant power in the lower heavy domain four times, two sessions in each of the mid-follicular and mid-luteal phases, once with carbohydrate and once with placebo in each phase, and then rode a 4-km time trial.

Carbohydrate made the time trial faster in both phases (p = 0.005): 9.9 vs 10.4 min in the follicular and 9.8 vs 10.0 min in the luteal phase. With carbohydrate the potentiated twitch fell a little more (−46% and −50% vs −43% and −43%; p = 0.044), and breathlessness was rated higher in the luteal phase with carbohydrate than with placebo.

Maximal voluntary force, voluntary activation, low-frequency fatigue, RPE, rating of fatigue and leg pain did not differ. The authors conclude that performance and performance fatigability do not differ between these two phases after this bout, and that carbohydrate helps similarly in both.