The social media consensus on cold plunges and testosterone is incomplete and sometimes wrong. Dr. Thomas Seager, speaking with Ben Greenfield, is specific about what the evidence shows — and the nuance matters, because the direction of the effect depends entirely on when you plunge relative to when you train.
This is a conversation that has implications for how millions of men and women structure their cold practice. The finding is counterintuitive, well-documented, and almost never discussed with appropriate precision.
Cold after exercise: testosterone suppressed. Cold before exercise: testosterone elevated. This is not a theoretical distinction — Seager has documented it across case studies, and the mechanism is coherent with what endocrinology has long established.
Post-exercise cold suppresses the inflammatory signal that triggers anabolic hormone release. The inflammation that cold is specifically used to reduce is part of the hormonal cascade that includes growth hormone and testosterone. Intercept the signal, and you intercept the hormone response.
Pre-exercise cold does the opposite. The hypothalamic-pituitary-gonadal axis responds to cold exposure by increasing luteinizing hormone. LH drives testosterone synthesis in the testes. Cold before training therefore arrives as a hormonal primer — elevating LH before the additional testosterone stimulus of the training session itself.
Women also produce testosterone — in amounts roughly ten times lower than men, but physiologically significant for energy, libido, mood, muscle function, and bone density. The assumption that testosterone optimization is a male-specific concern is both common and incorrect.
Seager's case studies included women, and the findings were parallel: pre-training cold plunge (discussed further here) produced meaningful testosterone elevations in female subjects as well. Most women are unaware of how beneficial testosterone is for them, and of how amenable their hormonal profile is to the same cold timing principles that apply to men.
This has implications for how women structure their training and cold practice — particularly during phases of the cycle when testosterone naturally drops.
Greenfield describes his experience with the Morozko Forge — Seager's ice bath, capable of maintaining temperatures below 34°F — with the enthusiasm of someone who genuinely relishes the extreme version of the practice. The ice that forms on the surface. The icicles that greet a morning plunge.
There is a psychological dimension to this framing worth acknowledging: some practitioners find that the ritual of extreme cold — the preparation, the entry, the exit — carries a quality of felt aliveness that more moderate protocols do not fully replicate. This is not science. It is phenomenology. And it is real.
The distinction matters because Seager is careful to note that the physiological benefits do not require the extreme temperatures that Greenfield describes. The hormonal effect plateaus. The psychological effect of the extreme experience is a separate variable — one that some individuals value and some do not.
For most people, the practical recommendation from this conversation is straightforward: if testosterone support is among your goals for cold practice, plunge in the morning, before training.
The full protocol Seager endorses for testosterone support: two to four minutes at 34–50°F, morning, before any strength or endurance training. Daily frequency produces the most consistent hormonal effect. The window of LH elevation lasts several hours, covering most morning training sessions.
If morning plunging is not feasible, the next best timing is at least four hours after training. This allows the post-exercise anabolic cascade to complete before cold attenuates it. The worst timing — cold within 30–60 minutes after a strength session — should be avoided if testosterone support is the goal.