Every serious recovery facility in the world now has the same two-station setup: a sauna and a cold plunge, sitting ten feet apart. What was once a Nordic ritual and a Russian tradition has become a global performance protocol, driven partly by research, partly by social media, and partly by the growing realisation that the simplest interventions often produce the most measurable results.
The cold plunge and sauna combination, known formally as contrast therapy or hot cold therapy, has moved from fringe to mainstream in under five years. Plunge, Ice Barrel, and a dozen other companies have turned cold immersion into a consumer category. Home saunas are a booming market. And the science has quietly caught up with the enthusiasm.
But doing both is not the same as doing both well. The sequencing matters. The temperatures matter. The timing matters. And the one rule most people get wrong, what you end on, might be the most important variable of all.
The short answer: Combine sauna (80–100°C) with cold plunge (1–15°C) in alternating rounds. Start with heat, transition to cold. The Søeberg Principle says to end on cold, forcing your body to reheat itself extends the metabolic benefits. Avoid cold plunging immediately after strength training if hypertrophy is the goal.
What Contrast Therapy Actually Does to Your Body
The mechanism is deceptively simple: you're cycling between vasodilation and vasoconstriction, and the transitions are where the work happens. In a sauna at 80–100 degrees Celsius, blood vessels dilate aggressively. Cardiac output rises by 60–70%. Blood rushes to the skin, core temperature climbs, and the cardiovascular system enters a state that closely mimics moderate aerobic exercise. Step into a cold plunge at 1–5 degrees Celsius and the opposite occurs: vessels constrict, blood retreats to the core, and the body mounts a powerful sympathetic response to defend its temperature.
This cycling, hot to cold and back again, creates a vascular pump effect. Each transition forces the circulatory system to adapt rapidly, improving vascular elasticity and endothelial function over time. A 2007 meta-analysis on contrast water therapy found it significantly reduced muscle soreness and improved recovery markers compared to passive rest.
But the more compelling data sits on the cold side of the equation. Brief cold exposure triggers a dramatic release of norepinephrine, a study published in the European Journal of Applied Physiology found that immersion in cold water produced a 200–300% increase in norepinephrine levels. That is not a subtle shift. Norepinephrine sharpens focus, elevates mood, reduces inflammation, and plays a central role in the conversion of white fat to metabolically active brown fat. The cold plunge is not just a recovery tool. It is a neuroendocrine intervention.
Combined with sauna, which elevates heart rate, triggers heat shock proteins, and drives its own anti-inflammatory cascade, contrast therapy delivers a broader physiological stimulus than either modality alone.
The Søeberg Principle: Why You Should End on Cold
If you take one thing from this article, let it be this: end your contrast session on cold, not hot. This is the core insight from Dr. Susanna Søeberg's research on deliberate cold and heat exposure, and it has become known as the Søeberg Principle.
The logic is straightforward. When you finish on cold and then step out, without a hot shower, without warming yourself by a fire, you force your body to reheat itself. That active reheating process is metabolically expensive. It demands energy. It activates brown adipose tissue. It extends the caloric and hormonal benefits of the session well beyond the moment you dry off.
Finish on hot, and you skip this entirely. The sauna has already done the warming for you. Your body has nothing to work against. The metabolic afterburn, the part that makes contrast therapy more than a pleasant experience, is significantly blunted.
Andrew Huberman's deliberate cold exposure protocols reinforce the same principle: end on cold, resist the urge to warm up artificially, and let your physiology do the work.
The discomfort is the point.
This does not mean the cold plunge must be the last thing you do before leaving the facility. A brief rest period at room temperature after the final cold exposure is fine, and for most people, advisable. The key is that you do not return to the sauna or a hot shower to "take the edge off." You let the shiver do its job.
Sequencing, Temperature, and Duration: The Practical Protocols
The default sequence for contrast therapy is sauna first, cold plunge second, and most of the research supports this order. Starting with heat raises your core temperature and primes the cardiovascular system for the cold shock that follows. It also makes the cold more tolerable, which matters when you are asking someone to sit in water that is barely above freezing.
Here are three protocols, scaled by experience.
Beginner Protocol (2 rounds)
Start here. The cold temperatures are moderate and the durations are short. The goal is to build tolerance and learn to control your breathing during the cold exposure. Two rounds is enough to trigger the norepinephrine response and begin the vascular adaptation.
Intermediate Protocol (3–4 rounds)
This is the sweet spot for most regular practitioners. The sauna durations are long enough to accumulate meaningful heat shock protein activation, and the cold is sharp enough to produce a robust neuroendocrine response. Three to four rounds gives you 45–80 minutes of total contrast time, a genuine session, not a token effort.
Advanced Protocol (4+ rounds)
This demands conditioning. Water at 1–3 degrees Celsius is punishing, and spending 3–5 minutes in it requires both physical adaptation and mental discipline. The sauna temperatures are at the upper range of what most commercial saunas produce. Do not jump to this protocol. Earn it.
For all three levels, the Cleveland Clinic recommends starting conservatively, especially for anyone with cardiovascular conditions, and consulting a doctor before beginning cold immersion protocols.
When Not to Do Contrast Therapy
If your primary goal is muscle hypertrophy, cold plunging immediately after strength training may be working against you. This is the caveat that most cold plunge evangelists skip over, and the research is increasingly clear on it.
A 2015 study in The Journal of Physiology found that cold water immersion after resistance training attenuated long-term gains in muscle mass and strength. The mechanism makes sense: the inflammatory response that follows strength training is not a problem to be solved, it is the signal that initiates muscle protein synthesis and satellite cell activation. Cold exposure blunts that signal. You are suppressing the very process you trained to trigger.
This does not mean contrast therapy and strength training cannot coexist. It means they need to be separated. If you trained legs in the morning, do your contrast session in the evening, or better yet, on a rest day. If your training is endurance-focused, the timing matters less; cold exposure does not appear to blunt aerobic adaptations the way it impairs hypertrophy signalling.
For a deeper look at how to sequence sauna around your training, we have covered this in detail.
The rule of thumb: contrast therapy is a recovery and adaptation tool. Use it when recovery is the priority. Keep it away from sessions where the acute inflammatory response is the priority.
Making the Most of Your Time in the Heat
The cold plunge gets the headlines, but the sauna is where you spend the majority of your contrast session, and the quality of that time matters.
Temperature stratification inside a sauna is significant. The air near the ceiling can sit 10–15°C hotter than at bench level, and your head, uninsulated and highly vascularised, absorbs that heat disproportionately. Your hypothalamus reads the head temperature as a proxy for core temperature and fires the exit signal early. For most people, it is not their body that gives out in the sauna. It is their head.
This is where a sauna hat earns its place. A merino wool hat insulates the scalp from the hottest air in the room, allowing the body to accumulate heat at a more even rate and delaying the premature exit signal. In a contrast therapy context, this is not marginal, it is the difference between completing your planned sauna duration and cutting it short on round three.
The Ri Sauna Crown is built from 100% Australian merino wool, designed in Ireland for people who treat contrast therapy as a protocol, not a novelty. Merino breathes, manages moisture, and regulates temperature in both directions, it does not trap steam against your scalp the way felt or synthetics do. It sits light, stays dry, and lets you finish the session you planned.
More time in the heat. A cleaner transition to the cold. That is how the rounds add up.
Frequently Asked Questions
The questions that come up most often, answered plainly.
Should I do sauna or cold plunge first?
Sauna first. Starting with heat raises your core temperature, primes the cardiovascular system, and makes the cold more tolerable. Most research on contrast therapy uses this order. The sauna opens the vasodilation phase; the cold plunge provides the vasoconstriction response. That sequence, heat then cold, is where the vascular pump effect comes from.
What is the Søeberg Principle?
The Søeberg Principle, from Dr. Susanna Søeberg's research, states that you should end your contrast therapy session on cold, not hot, and avoid warming up artificially afterward. By forcing your body to reheat itself, you extend the metabolic benefits: brown adipose tissue activation, elevated norepinephrine, and increased caloric expenditure. Finishing on hot skips this entirely.
How cold should a cold plunge be?
Beginners should start at 10–15°C. Intermediate practitioners can work down to 5–10°C. Advanced users target 1–5°C. The norepinephrine response is dose-dependent, colder water produces a larger release, but the key is consistent exposure over time, not one punishing session. Start moderate and progress as your tolerance develops.
Can I cold plunge after lifting weights?
If hypertrophy is your goal, no, or at least, not immediately. A 2015 study in The Journal of Physiology found that cold water immersion after resistance training attenuated long-term gains in muscle mass and strength. The post-training inflammatory response is the signal that drives adaptation. Cold blunts that signal. Separate your cold exposure from strength training by at least 4–6 hours, or use contrast therapy on rest days.
How many rounds of contrast therapy should I do?
Beginners: 2 rounds. Intermediate: 3–4 rounds. Advanced: 4–6 rounds. Each round consists of one sauna session followed by one cold plunge, with a brief rest period in between. More rounds provide greater cumulative stimulus, but the quality of each round matters more than the count. Always end the final round on cold.
Do I need a sauna hat for contrast therapy?
It is not strictly required, but it meaningfully improves the sauna portion of each round. Temperature stratification means your head sits in air that is 10–15°C hotter than at bench level. A wool sauna hat insulates the scalp, delays the hypothalamic exit signal, and lets you complete longer sauna rounds without cutting short. In a multi-round contrast session, that extra time compounds across every round.
Sources
- Cochrane DJ. "Alternating hot and cold water immersion for athlete recovery: a review." Physical Therapy in Sport, 2004.
- Leppäluoto J et al. "Effects of long-term whole-body cold exposures on plasma concentrations of ACTH, beta-endorphin, cortisol, catecholamines and cytokines in healthy females." European Journal of Applied Physiology, 2008.
- Roberts LA et al. "Post-exercise cold water immersion attenuates acute anabolic signalling and long-term adaptations in muscle to strength training." The Journal of Physiology, 2015.
- Laukkanen JA et al. "Association Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality Events." JAMA Internal Medicine, 2015.
Last reviewed: March 2026
The information in this article is for educational purposes only and is not medical advice. Consult your doctor before beginning any sauna or cold immersion protocol.
Last updated: 2 April 2026