Background and Purpose: Hormonal fluctuations during the menstrual cycle can affect muscle performance in women. This study aimed to investigate the effects of concurrent (concurrent) training based on the follicular and luteal phases of the menstrual cycle on muscle strength in healthy young women.

Methods: This semi-experimental study was conducted on 23 healthy young women (mean age 35.17 ± 2.08 years) with regular menstrual cycles (mean cycle length 26.52 ± 1.83 days). The training program consisted of performing concurrent exercises separately in each phase, over 8 weeks, three sessions per week. To prevent interference of training effects from the follicular phase on the luteal phase results, a specific time interval was assigned for each participant.

Results: Findings showed that muscle strength significantly increased after the training period in both the follicular phase (t=24.78, P<0.001) and the luteal phase (t=24.24, P<0.001). However, the magnitude of strength improvement was greater in the follicular phase than in the luteal phase (t=4.446, P=0.040).

Conclusion: Training during the follicular phase of the menstrual cycle is more effective than during the luteal phase in enhancing muscle strength in healthy young women.