Cold plunges suppress testosterone. You've probably heard this. It's been circulating as fact in training communities for years, and it's led some men to quietly drop cold exposure from their protocols, worried they're undermining their hormonal health. Thomas Seager's work cuts through this cleanly: the claim is not wrong, it's incomplete. The direction of the effect depends entirely on timing.
Cold after exercise suppresses the anabolic signal. Cold before exercise elevates luteinizing hormone and primes testosterone synthesis. Same temperature, same duration, opposite outcome. Order determines everything.
This finding doesn't exist in isolation. The post-exercise cold debate has been running in sports science for over a decade. Leppäluoto's Finnish sauna research and Tipton's work on cold water immersion both point to the same underlying tension: the inflammatory response to training isn't purely damage — it's signal. It initiates the hormonal cascade that drives adaptation. Blunt that signal with ice immediately after a session, and you're not just reducing soreness. You're interrupting the conversation your muscles are having with your endocrine system.
Seager's contribution is making the hormonal consequence specific and measurable. Four documented case studies showing testosterone suppression from post-exercise cold, and elevation from pre-exercise cold, gives the timing principle a precision that general warnings about "cold and recovery" have always lacked.
Not everyone finds this clean. Some researchers argue that luteinizing hormone elevations from cold are transient — minutes to low hours — and that the training-induced testosterone stimulus may dominate regardless of pre-loading. The case study format also has obvious limitations compared to controlled trials with larger populations. Seager himself distinguishes between the physiological plateau of temperature and the psychological dimension of extreme cold — acknowledging that some of what practitioners report may be phenomenological rather than endocrinological.
What I'd say is this: the mechanism is coherent with what endocrinology has long understood about the HPG axis and stress hormones. Whether the magnitude of the effect in practice is clinically significant for every individual is still an open question. But the directional principle — cold before, not after, if testosterone support is the goal — is grounded in real biology.
Two to four minutes at cold temperature, morning, before your training session. If morning isn't feasible, wait at least four hours after training before plunging. That window allows the post-exercise anabolic cascade to complete before cold attenuates it. Cold within sixty minutes of a strength session is the configuration to avoid if testosterone support matters to you.
The women's angle here is genuinely underexplored. Testosterone in women — at roughly one tenth the male concentration — governs energy, libido, mood, and muscle function in ways most women are never told about. Seager's case studies found parallel effects in female subjects: pre-training cold produced meaningful testosterone elevations. The timing principle doesn't care about biological sex. It cares about the sequence of stressors. That's worth sitting with. Cold exposure is usually marketed to women as a stress reduction or skin health tool. The hormonal optimization angle — the same one that drives male cold practice — applies equally, and almost no one is talking about it.