The internet is full of wellness influencers insisting that women should tailor their workout routines to their menstrual cycles: heavy lifting around ovulation, gentle yoga during the luteal phase. It sounds intuitive - hormones fluctuate, so why wouldn’t strength?

But according to Dr Marianna Apicella, a researcher at the University of Leicester specialising in female physiology, that advice is built on a foundation of air. “High-quality evidence supporting that is seriously lacking,” she says. “There’s not really much concrete evidence for it.”

Apicella’s own research, which examined muscle-building across the menstrual cycle’s hormone fluctuations, found no significant difference between phases - early follicular, late follicular, or luteal. The body’s ability to build muscle appears broadly consistent throughout. In other words, you’re not likely to gain more strength or muscle at one point in your cycle than another, no matter what your favourite wellness TikToker claims.

She does offer a caveat: “Everyone’s different, so some people might feel stronger at certain points. And symptoms are the key thing that’s actually playing into this for people.” Cramps, fatigue, or low mood can certainly tank a workout, while others sail through the month symptom-free. Your muscles may be working just as effectively, but your experience of exercising can still fluctuate.

Apicella says more research is needed into how women’s bodies respond to exercise. In the meantime, the most evidence-based advice? Pay attention to how you feel - and maybe skip the influencer-approved cycle-syncing spreadsheet.