August 2026

Menstrual Cycle Phase-Based Training Fallacy

Social media influencers excel at taking nuggets of facts and weaving anything from conspiracies to profit-making promises. The fitness arena is rife for such promises because who doesn’t want to get fitter, stronger, or leaner by optimizing one’s regimen? Short of proper diet, hard work, and sufficient rest, plenty of rationales for not seeing the results you want have been promoted.

With the profound roles that hormones play in every aspect of health, it makes sense that people would expect them to play a role in fitness, too.

Hence the menstrual cycle phase-based training (MCPBT) hypothesis which we covered just last month. This contends that a woman’s cycle, with its fluctuations of estradiol and progesterone to prepare the body for fertilization and pregnancy, might influence their ability to get stronger. Training in synch with the MC might optimize her strength and muscle mass gains, some think.

Twenty-four eumenorrheic women resistance trained for 3 consecutive months where one leg served as the control for the other. Of the 48 legs, each was randomly assigned as a non-exercise control (C), traditional training across both the luteal and follicular stages (EX), high-volume during the follicular and low-volume during the luteal phases (HI-FOL), and the converse (HI-LUT). Their phases were checked with blood and urine tests. Leg muscle mass and maximal strength were measured pre- and post.

“MCPBT confers neither hypertrophy nor strength advantages over traditional continuous RET.

Training volume-load” was what really mattered regardless the time of month. However, phase-based adjustments based on individual preferences, while not necessary, should still be respected.                                             

MSSE May 2026            

But Maybe The Menstrual Cycle Impacts Performance

The menstrual cycle (MC) may not impact strength training outcomes but might influence neuromuscular performance in female athletes. There are 3 phases of the MC that have been suspected to impact athletic performance: early follicular (EF), late follicular (LF), and late luteal (LL). For example, during LL menstruation is approaching. The EF sees estradiol starting to rise and the LF sees it peaking. Estradiol is linked with ligamentous laxity while menstruation can be accompanied by a sense of bloat, discomfort, and abdominal pain.

Spanish researchers tested 32 adolescent female basketball and volleyball players across 3 consecutive natural (no birth control meds) periods on their countermovement jump (CMJ: drop then jump), and bench press repetitions (BP: at 80% of their 1-rep max).

CMJ height and upper-body endurance were “significantly reduced during” EF compared to the LF or LL.

However, these differences ranged from small to moderate. As the authors noted, “even small decrements may influence readiness or testing outcomes in high-performance environments”. The EF phase, they suggested, with its lower estrogen and progesterone concentrations, “may be less favorable for neuromuscular output”.

The authors wisely noted that all the “observed changes may not be exclusively hormonal: menstrual symptoms, fatigue, and psychological state are also plausible contributors”.

They also pointed out that adolescents’ cycles tend to be more variable in length and phases so, unless rigorously tested, athletes or coaches can’t know for sure what phase is driving performance. Once you hit the court, only performance counts.                          

JSCR May 2026

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