“These findings highlight that while CAF can enhance certain aspects of cognitive performance in female athletes, responses in physical performance may vary and require further investigation,” wrote researchers in Tunisia, Turkey, Italy, and Germany.
They added that caffeine may improve selected neuromuscular outcomes, but phase-specific ergogenic evidence remains limited.
Therefore, given the small sample size and study limitations, the findings “are intended to generate hypotheses for future research rather than provide definitive practical recommendations.”
How the menstrual cycle influences performance
Male athletes have relatively stable hormonal influences, whereas female athletes experience cyclical hormonal changes that can affect their performance.
Estrogen and progesterone can have opposing effects on the brain and nervous system, influencing both cognitive and neuromuscular performance in female athletes. Furthermore, factors such as stress, recovery, intense training, and energy availability can disrupt menstrual function, causing menstrual irregularities and further impacting performance.
In light of this, personalized training and supplementation strategies have emerged as a key strategy to optimize female performance.
Commenting on the current study, Sharon Madigan, head of performance at Sport Ireland Institute, told NutraIngredients that the impact of caffeine on performance across phases of the menstrual cycle remains unanswered.
“One of the issues that this might also reinforce is the narrative around ‘phased based’ anything which is doing the rounds. There is no science to support some of the statements that are doing the rounds on the socials at the minute,” she said.
“What we do know with confidence is that supporting hormonal health through adequate energy availability, good levels of nutrients such as iron, which can be lower in females and the overall dietary quality matters for female athletes. That foundation has far stronger evidence than any phase specific supplement strategy.”
Study details
The randomized, double-blind, placebo-controlled study involved 12 female athletes with regular menstrual cycles who completed three consecutive testing sessions, each conducted in a distinct phase of the menstrual cycle, with a 7–10 day rest period between them. Each participant completed two experimental sessions per menstrual cycle phase (MCP), one with a placebo and one with 400 mg of caffeine ingested an hour before testing. Participants were advised to avoid caffeine consumption for 24 hours before each experimental session.
The researchers evaluated cognitive performance using a reaction time test (RTT) and a vigilance test (VT), and physical performance using a counter-movement jump (CMJ) test, a repeated sprint test (RST), and a time-to-exhaustion (TTE) test conducted at 90% of each subject’s maximal aerobic power.
Participants also completed a menstrual diary to characterize their menstrual cycles and had their ovulation, serum estrogen, and progesterone measured using appropriate methods.
The results showed that caffeine supplementation significantly improved VT performance across all phases of the menstrual cycle and reduced RT.
CMJ values were significantly higher in the late-follicular phase compared to other menstrual phases, and in the mid-luteal phase with caffeine ingestion. Caffeine attenuated fatigue-related performance declines in later sprints, but TTE was not affected by the supplementation.
The researchers noted that their findings are preliminary and the results should be interpreted with caution, especially since individual responses to caffeine may vary. They called for larger studies to inform the development of definitive practical guidelines.
Source: Nutrients; doi: 10.3390/nu18101512; “Effects of Caffeine Supplementation on Cognitive Function and Neuromuscular Performance Across Menstrual Cycle Phases in Eumenorrheic Female Athletes: A Randomized, Double-Blind Placebo-Controlled Pilot Trial.” Authors: I. B. Hsen et al.
