Cycle, training & nutrition

Much of sports-science research was done on men and applied to everyone. Exercise physiologist and nutrition scientist Dr. Stacy Sims — PhD from the University of Otago, with research roles at Stanford and Auckland University of Technology and 100+ peer-reviewed papers¹² — is one of the best-known voices arguing that female physiology deserves its own research and its own approach, not a scaled-down male template.

That core idea — that sex differences are real and worth accounting for — is well supported and widely shared in the field.

The popular advice to precisely periodize training and nutrition by cycle phase is still emerging science. The most rigorous review to date pooled the available studies and found that, on average, cycle phase has only a trivial effect on exercise performance — and that the underlying studies were largely low quality and highly variable³.

Its own conclusion is the useful one: because the average effect is small but individual responses vary a lot, a personalized approach — tracking how you respond across your own cycle — is more sensible than any single universal rule³.

This is exactly what Cycle Journal is for. Alongside your temperature and phases, jot down how you feel in your daily notes — energy, sleep, strength, mood, cravings, soreness — and look back across a few cycles. Patterns that are real for you (say, lower energy in the late luteal phase, or strong sessions mid-cycle) will show up, and you can plan around them. Patterns that are just noise won't.

That is the evidence-based version of “training with your cycle”: not a rigid calendar, but your own data, observed over time.