Suplementação de cafeína como estratégia para atenuar o declínio de força na fase folicular do ciclo menstrual

Abstract

The menstrual cycle might impair muscular performance, but whether caffeine would mitigate potential loss in muscular performance in different phases of the menstrual cycle is an underexplored question. The aim of the present study was to compare the effects of caffeine on muscular performance in the early-follicular and mid-luteal phases of the menstrual cycle. After preliminary visits for familiarization with the experimental tests, 14 healthy resistance-trained women performed a sequence of tests [countermovement jump (CMJ), and maximal voluntary isometric contraction (MVIC), one-repetition maximum (1-RM), and repetitions-to-failure (RF) test at 80% of 1-RM in the half-squat exercise] in the early-follicular and the mid-luteal phases after placebo or caffeine ingestion. There was a condition vs. Menstrual cycle phase interaction for 1-RM, CMJ, and RF tests (p < 0.026). The performance during the 1- RM, CMJ, and RF tests was lower in the early-follicular than in the mid-luteal phase (p < 0.05). Caffeine, however, increased 1-RM in the early-follicular (Hedges g = 0.90, p < 0.05) but not in the mid-luteal phase (Hedges g = 0.16, p < 0.05). In addition, magnitude of gains in CMJ height and RF with caffeine ingestion were higher in the early-follicular (Hedges g = 1.20 and 1.85, p < 0.05) than in the mid-luteal phase (Hedges g = 0.55 and 0.87, p < 0.05). Caffeine also increased MVIC regardless of the menstrual cycle phase (main effect of condition, p < 0.05). In conclusion, caffeine improves muscular performance in both early-follicular and mid-luteal phases of the menstrual cycle. Nevertheless, the greatest ergogenic effect during the early-follicular phase supports the use of caffeine to mitigate the decline in muscle force in this phase.