Chris Gthin has been doing contrast therapy since the 90s and credits it — alongside other practices — with reducing his biological age every year since 2014. His protocol is straightforward: 15 to 20 minutes sauna, 2 to 3 minutes cold plunge, repeated three times. He points to muscle soreness reduction, faster recovery, and two benefits that don't get enough attention in most contrast therapy discussions: emotional stability and blood sugar regulation.
That last pair is worth sitting with. Most people come to contrast therapy for the physical recovery angle. Fewer people talk about what it does to your mood and your metabolic signaling. Gthin noticed it. The research backs it up. And it changes how you should think about when and why to use this practice.
The knowledge base has a 2023 systematic review on contrast therapy in soft tissue injury management that lands in an interesting place. Subjective recovery — how people feel, how sore they report being — consistently improves. Participants felt better. They felt less muscle soreness. But the objective markers? More equivocal. The review is honest about this gap between perceived recovery and measurable physiological change.
That's not a knock on contrast therapy. It's a nuance. Perceived recovery matters enormously. If athletes train harder and recover faster subjectively, performance improves regardless of what the biomarkers say. But it does mean we should be honest about what we know and what we don't.
The 2025 paper on thermal interventions and skeletal muscle adaptation fills in part of the picture. Heat specifically enhances protein turnover — your body becomes more efficient at repairing and building muscle tissue when exposed to heat. This is the sauna's contribution to the equation. Not just relaxation. Actual cellular signaling that accelerates repair.
Timing is one area where the research speaks clearly. A 2022 cryotherapy study found that whole-body cold treatment immediately post-exercise outperformed treatment delayed by four hours — smaller decrease in muscle strength, faster return to baseline. The window matters. Waiting doesn't serve you the same way.
The disagreement in the field is subtler. Some researchers, Huberman among them, have raised the question of whether cold exposure immediately after strength training might blunt hypertrophy signals — specifically suppressing the inflammatory response that triggers muscle growth. If you're optimizing for building muscle, there's a case for separating cold from your training window. If you're optimizing for recovery and general resilience, contrast therapy wins. These goals aren't always the same.
The emotional stability piece Gthin mentions isn't incidental. When you alternate between heat and cold, you're running your autonomic nervous system through a deliberate cycle. Heat activates the parasympathetic — you soften, you open. Cold activates the sympathetic — norepinephrine floods your system, alertness sharpens. Repeat this three times in a session and you've essentially trained your nervous system's switching mechanism.
The blood sugar regulation follows from this. Norepinephrine and the muscle contractions from cold-induced shivering both improve glucose uptake. Sauna has separately been shown to improve insulin sensitivity. Together, you're hitting glucose regulation from two different angles. For people managing metabolic health, this is an underappreciated benefit hiding inside what most people call a "recovery tool."
Gthin's protocol is solid and the research supports it. Start with heat — 15 minutes minimum to trigger the protein turnover and heat shock protein response. Move immediately to cold — 2 to 3 minutes is enough. Repeat the cycle two to three times. Hydrate before and after, and take electrolytes seriously; you're losing minerals through sweat that affect everything from muscle function to mood.
Do this three to four times per week. Consistency compounds in ways that individual sessions don't. The nervous system adaptation, the metabolic benefits, the emotional equilibrium Gthin describes — these aren't acute effects. They're the product of showing up repeatedly and letting your biology catch up to the demand you're placing on it.