The Effect of Caffeine on the Velocity of Half-Squat Exercise during the Menstrual Cycle: A Randomized Controlled Trial

Abstract

Recent literature confirms the ergogenic effect of acute caffeine intake to increase muscle strength and power in men. However, the information about the effect of caffeine on muscle performance in women is uncertain and it is unknown whether its ergogenicity is similar during the menstrual cycle. The goal of this investigation was to assess the effect of acute caffeine intake on mean and peak velocity of half-squat exercise during three different phases of the menstrual cycle. Thirteen trained eumenorrheic athletes (age = 31 ± 6 years; body mass = 58.6 ± 7.8 kg) participated in a double-blind, crossover and randomized experimental trial. In the early follicular (EFP), late follicular (LFP) and mid luteal phases (MLP), participants either ingested a placebo (cellulose) or 3 mg/kg/bm of caffeine in an opaque and unidentifiable capsule. In each trial, participants performed a half-squat exercise at maximal velocity with loads equivalent to 20%, 40% 60% and 80% of one repetition maximum (1RM). In each load, mean and peak velocity were measured during the concentric phase of the exercise using a rotatory encoder. In comparison to the placebo, a two-way ANOVA showed that the ingestion of 3 mg/kg/bm of caffeine increased mean velocity at 60% 1RM in EFP (Δ = 1.4 ± 2.7%, p = 0.04; ES: 0.2 ± 0.2) and LFP (Δ = 5.0 ± 10.4%, p = 0.04; ES: 0.3 ± 0.4). No other statistical differences were found for the caffeine-placebo comparison for mean velocity, but caffeine induced an ergogenic effect of small magnitude in all of the menstrual cycle phases. These results suggest that the acute intake of 3 mg/kg/bm of caffeine induces a small effect to increase movement velocity during resistance exercise in eumenorrheic female athletes. The positive effect of caffeine was of similar magnitude in all the three phases of the menstrual cycle.

Caffeine increases strength and power performance in resistance‐trained females during early follicular phase

“…As an example, a recently published study showed that half squat velocity was increased by 1.4%, 5%, and 5.3% in the early follicular, late follicular, and mid-luteal phase, respectively. 17 Thus, ensuring caffeine research in females is conducted during the same menstrual cycle phase is important and furthermore, which phase could potentially affect the effect size. Moreover, only one 15 of the two studies comparing effects of caffeine on strength performance between the sexes controlled for menstruation cycle phase.…”

“…Moreover, a recent study found differences in the effect of caffeine on power performance between the phases in the menstrual cycle. 17 It, therefore, seems important to control for stages in the menstrual cycle to further establish clear recommendations for the use of caffeine in females. The early follicular phase of the menstrual cycle has shown the lowest variability in oestradiol and progesterone concentration, 18 and the sex hormone levels in this phase are similar to the levels in females using hormone contraceptives.…”

The effects of different doses of caffeine on maximal strength and strength-endurance in women habituated to caffeine

“…Second, the hormonal changes, as a result of the menstrual cycle were not controlled in the investigation. However, recent research has found that CAF exhibits ergogenic effects across the menstrual cycle with bene ts on endurance [63], anaerobic [64] and strength-based exercise performance [30]. Lastly, the current investigation has determined the effects of two doses of CAF on resistance exercise performance while the effect of higher and lower doses of CAF, in women habituated to CAF has to be investigated in further research.…”

“…In addition, some of the caffeine-induced stimulant effects are of smaller magnitude in women than in men [29]. However, recent evidence suggests that the ergogenic effects of CAF on muscle performance is present in the early follicular, late follicular, and mid luteal phases [30], suggesting a stable effectiveness of CAF to increase muscle performance across the menstrual cycle. Furthermore, two recent investigations have found that the ergogenic effect of CAF may be of similar magnitude in men and women, although these investigations were carried out under aerobic conditions lasting from approximately 6 to 60 min [16,17].…”

Effects of Caffeine and Coffee on Human Functioning

“…However, the ergogenic effect of caffeine was inferior in women than in men in strength-and power-based tests, even when the same dose of caffeine was being administered. This significant, although low in magnitude, effect of caffeine to increase muscle power and force in women was confirmed by Romero-Moraleda [12], but these authors suggested that caffeine's ergogenicity was similar across the menstrual cycle (by investigating placebo-caffeine comparisons in the early follicular, late follicular and mid-luteal phases). All these investigations have contributed to explaining the effect of caffeine on human performance, which is present in several exercise situations and with several dosages, although further investigations should be carried out to explain the individual differences in the magnitude of the ergogenic effect of caffeine [13].…”