Menstrual Cycle Does Not Affect Peak Torque or Fatigue in Resistance-Trained Women.

The effects of estradiol and progesterone fluctuations during the menstrual cycle (MC) on strength and fatigue remain unclear. This study investigated their impact on peak torque and fatigue in isokinetic tests. Eleven strength-trained women performed five knee extensions and flexions to assess maximum peak torque, rating of perceived exertion (RPE), and rating of perceived pain (RPP). A separate protocol of 60 repetitions was used to evaluate peak torque, total work, percentage of work fatigue, RPE, RPP, and blood lactate concentration before and after exercise. MC phases were determined using a combination of calendar tracking, urinary ovulation tests, and serum hormone analysis. A one-way repeated-measures analysis of variance, followed by Bonferroni's post hoc tests and effect size calculations (partial eta-square), analyzed differences across six MC phases. No significant differences were observed in peak torque, RPE, or RPP during knee extension and flexion (p>0.05). Similarly, fatigue parameters assessed during the 60-repetition test showed no significant variation across MC phases (p>0.05). However, blood lactate concentrations were significantly higher postexercise than preexercise (p<0.05). These findings suggest that strength performance and muscle fatigue are not influenced by hormonal fluctuations across the MC in strength-trained women.