Cold Plunge & Sauna:
Good or Bad
for Your Gains?

The short answer — before we go deep

The wellness industry has sold cold plunges and saunas as universally beneficial recovery tools. The science is more specific than that — and more interesting. The truth depends entirely on what you are trying to achieve, when you use them, and how you combine them with your training. Here is the one-line summary for each:

What cold actually does to the body

Cold water immersion triggers a cascade of physiological responses that explain both its benefits and its drawbacks for athletes. Understanding the mechanism is what allows you to use it strategically rather than reflexively.

The critical detail for gym-goers: vasoconstriction and inflammation suppression are exactly the mechanisms that make cold immersion feel so effective after a hard session — and exactly what attenuates muscle growth. Post-exercise inflammation is not purely damage to be minimised. It is a signalling environment that initiates muscle protein synthesis, satellite cell activation, and the downstream adaptations that make you stronger and larger. Blunt that inflammatory signal prematurely and you reduce the adaptation stimulus.

Cold water immersion and muscle growth: what the meta-analyses show

This is where the wellness industry narrative and the peer-reviewed evidence most clearly diverge. The research on cold immersion and hypertrophy is now robust enough to draw firm conclusions — and those conclusions should change how you use cold therapy if building muscle is a priority.

The most definitive analysis is the Piñero et al. (2024) systematic review and meta-analysis published in the European Journal of Sport Science, led by researchers at CUNY Lehman College including Brad Schoenfeld — one of the world's leading authorities on resistance training and muscle hypertrophy. The study reviewed 8 controlled trials and reached the following conclusions:

Supporting this at the molecular level, a 2025 study from Maastricht University published in Medicine & Science in Sports & Exercise (Betz et al.) directly measured microvascular blood flow and amino acid incorporation into muscle tissue following CWI. The findings were unambiguous: cold water immersion lowered skeletal muscle microvascular perfusion and directly blunted amino acid uptake into muscle — the raw material for muscle protein synthesis — during the post-exercise recovery window.

An earlier study from the Journal of Applied Physiology found that 15 minutes at 10°C following resistance training attenuated anabolic signalling markers and skeletal muscle fibre growth over a 7-week training period — while interestingly leaving absolute strength gains relatively intact. This distinction matters: cold immersion may harm hypertrophy more than it harms strength development.

The practical implication is clear: if your goal is maximum hypertrophy, avoid cold immersion in the hours immediately following resistance training. If you train twice a day, or have a competition the next morning, cold immersion is a legitimate acute recovery tool. If you have 48 hours before your next session, keeping the post-exercise inflammatory environment intact serves your long-term adaptation better.

What sauna does to the body — the molecular case

Sauna exposure is a hormetic stressor: a mild, controlled stress that activates protective biological responses disproportionately larger than the stress itself. The mechanisms are distinct from cold — and in several ways, more directly aligned with the goals of strength and endurance training.

Sauna, muscle growth, and longevity: the data

Unlike cold immersion, sauna does not blunt anabolic signalling. In fact, the research suggests it may actively support muscle growth — and the longevity evidence is among the strongest in the broader thermal therapy literature.

Infrared sauna and neuromuscular performance

A 2025 study from the University of Jyväskylä, published in Frontiers in Sports and Active Living (Ahokas et al.), investigated whether regular post-exercise infrared sauna use during a 6-week training period promotes neuromuscular performance and body composition changes in 40 female team sport athletes. The study represents one of the most methodologically rigorous tests of sauna's effect on resistance training outcomes in a real athletic population.

The longevity data: the Kuopio study

The most powerful long-term evidence for sauna comes from the Kuopio Ischaemic Heart Disease Risk Factor Study — a prospective cohort study that followed 2,315 middle-aged Finnish men for over two decades. Its findings established a dose-response relationship between sauna frequency and cardiovascular protection that has anchored the longevity conversation around heat therapy:

These figures are observational — they cannot establish that sauna directly causes mortality reduction, as they may reflect the lifestyle patterns of frequent sauna users. But the dose-response relationship and the biological plausibility of the mechanisms (HSP production, cardiac conditioning, anti-inflammatory signalling) make the connection compelling. No other low-effort, passive intervention in the literature produces associations of this magnitude with cardiovascular and all-cause mortality.

For athletes specifically, the sauna's value extends beyond longevity. Regular use improves heat acclimation — the body's ability to maintain performance in warm environments — and has been shown to improve time to exhaustion and reduce muscle soreness as a standalone recovery modality. Unlike cold immersion, none of these effects come at the cost of blunted adaptation when used post-resistance training.

Contrast therapy: what happens when you alternate hot and cold

Contrast therapy — the deliberate alternation of heat and cold exposures in repeated cycles — has become the defining recovery protocol of elite sport. LeBron James has used it for over two decades. Cristiano Ronaldo has a cryotherapy chamber installed at home. The current NBA standard, per Sports Illustrated, is approximately 3 minutes of cold at 39–42°F alternating with 15-minute infrared sauna sessions across multiple rounds.

The mechanism is physiologically elegant. Heat causes vasodilation — blood vessels expand, delivering oxygen and nutrients to fatigued tissue. Cold causes vasoconstriction — vessels contract, flushing metabolic waste and reducing inflammation. Alternating the two creates what researchers call a "vascular pump" effect: a rhythmic expansion and contraction of the vascular system that clears lactate, delivers nutrients, and modulates inflammatory signalling far more efficiently than either modality alone.

Contrast therapy vs. cold alone for recovery

A 2023 systematic review and meta-analysis published in Sports Medicine concluded cold water immersion was equal to or better than alternatives for recovering athletic performance after strenuous exercise. Crucially, the addition of heat phases in contrast therapy produces superior outcomes to cold alone for reducing delayed-onset muscle soreness (DOMS) and improving joint range of motion — findings confirmed by a 2025 scoping review in Medicina.

The hypertrophy caveat from cold immersion applies equally to the cold component within contrast therapy. If building maximum muscle is the priority following a resistance session, the sauna component is the element to preserve — the cold dips should be delayed or minimised. If the priority is recovery between two training sessions within 24 hours, the full contrast protocol is the most effective tool available.

When to use what — the evidence-based guide

The research supports a clear decision framework based on your training goal and session timing. This is not one-size-fits-all — it is goal-dependent.

Evidence-informed contrast therapy protocol

Total session: approximately 45–60 minutes. Frequency: 2–4× per week for general health; daily for athletes in active recovery phases. Hydrate consistently throughout.

Use it / skip it: the goal-based guide

• Use it

  Cold plunge after endurance or cardio training. CWI does not blunt endurance adaptations. For cyclists, runners, and team sport athletes recovering from aerobic sessions, cold immersion accelerates recovery without the hypertrophy trade-off.

• Time it

  Cold plunge after resistance training — wait 24 hours. If building muscle is a priority, avoid cold immersion in the window immediately following your weights session. Separate by at least 24 hours, or use cold only on off-days and endurance days.

• Use it

  Sauna after any training session. Sauna does not blunt anabolic signalling. Post-resistance sauna supports growth hormone elevation, heat shock protein production, and cardiovascular conditioning without attenuating hypertrophy. 15–20 minutes at 80–90°C is the evidence-informed dose.

• Use it

  Contrast therapy on recovery days or between double sessions. When you need to prepare for training again within 24 hours, the vascular pump effect of contrast therapy is your most powerful recovery tool. This is the elite sport application — prioritise it in periods of high training load.

• Use it

  Sauna 4× per week for longevity, independently of training. The Kuopio data suggests four or more sauna sessions per week produces the strongest longevity and cardiovascular benefit. This is a standalone health practice with a 40% reduction in all-cause mortality at the highest frequency — not merely a training recovery tool.

• Avoid

  Cold plunge immediately after a hypertrophy-focused resistance session. This is the one scenario where the evidence is clearest. Suppressing post-exercise anabolic signalling through vasoconstriction and inflammation blunting directly attenuates the muscle protein synthesis that drives growth. If gains matter to you, protect the post-training window.