Cold Plunge After a Workout: When to Plunge and Sauna

What cold water is good for: soreness and quick recovery

Cold water does have a real use. A Cochrane review by Bleakley and colleagues pooled 17 small trials with 366 people and found some evidence that cold water immersion after exercise reduced muscle soreness over the following one to four days, compared with resting or doing nothing. The authors rated the evidence as low quality, and most trials did not check properly for harms. In the few comparisons with other methods, including an active cool-down, there was no important difference, though the data were limited.

So cold water is a tool for feeling better quickly, not for building more muscle. It makes most sense when the next session matters more than long-term growth:

• two hard sessions in one day, or on back-to-back days;
• a competition or tournament spread over a weekend;
• a team sport where you play again within a day or two.

Soreness is not a sign that a workout worked, and it fades as your body gets used to training. Does muscle soreness mean a good workout? explains why.

How long to wait between lifting and a cold plunge

The honest answer is that we found no study that has tested it properly. The Roberts study used cold water straight after lifting. We do not know whether waiting two hours, six hours or until the next day removes the cost.

So these are cautious, common-sense choices rather than proven rules:

• Rest days are the safest choice if muscle is your goal.
• On training days, put as many hours as you can between them. Morning plunge, evening lift, or the other way round, is a more cautious choice than back to back.
• After cardio or a sports session, the cost is less clear, because the research above looked at lifting.
• If you love a cold plunge for how it makes you feel, keep it. Just keep it away from your lifting.

Saunas: what we know

Sauna research is mostly about health, not muscle.

Heart health. A large Finnish study (Laukkanen and colleagues, JAMA Internal Medicine, 2015) found that men who used a sauna four to seven times a week had a lower risk of dying from heart disease than men who used one once a week. That was an observational study, so it cannot prove the sauna itself was the cause: men who could fit in daily saunas may have differed in other ways.

Muscle growth. Research on saunas and muscle growth in people is thin. There is no good evidence that a sauna after lifting builds extra muscle, and none that it costs you any. Use it because you enjoy it, not because you expect it to grow your arms.

Weight loss. The weight you lose in a sauna is sweat, not fat. It comes back as soon as you drink.

Practical rules:

• Replace the fluid you sweat out, especially after a hard training session when you are already low.
• Avoid saunas after alcohol.
• Get out if you feel dizzy, sick or unwell, and do not stay in to hit a time.

Cold plunge and sauna timing at a glance

Your goal right now	Cold plunge	Sauna
Building muscle or strength	Rest days, or many hours away from lifting	Any time you enjoy it, with fluids
Losing fat	Rest days, or away from lifting	Any time, but sauna weight loss is water
Recovering fast between events	After the event, if it helps you feel better	Optional; watch hydration
Feeling good and relaxing	Away from lifting	Any time

Staying safe in cold water and heat

Cold water shock is the main danger. The RNLI, the UK's lifeboat charity, defines water below 15 °C (59 °F) as cold enough to cause it. Sudden cold makes you gasp and breathe fast, and it raises your heart rate and blood pressure, which the RNLI warns can trigger a heart attack, even in relatively young, healthy people. In open water, that gasp can also mean breathing in water.

• Get in slowly and keep your head above water. The RNLI says the first shock passes in under a minute, so give your breathing time to settle.
• Never plunge alone in open water, and never after drinking.
• Start short. There is no prize for the longest plunge.
• Get out if you shiver hard, feel numb or feel unwell.

Speak to your doctor or GP first if you have a heart condition, high or low blood pressure, Raynaud's or diabetes, are pregnant, or take regular medicines. Both cold water and heat put real strain on the heart and circulation.

What matters more than either

A cold plunge or sauna is a small add-on. Sleep, enough protein, a training program that keeps progressing and a sensible diet do far more for how you look and feel. Biohacking for lifters sorts the popular recovery tools by the evidence, and sleep and muscle growth covers the recovery tool that beats them all.

How coaching helps

Recovery questions are easier to answer when someone can see your whole week. With one-to-one coaching from CoachAk, your training program is written for you in a private app, and you log every workout, with personal bests and your coach's comments. Your weekly check-in takes about three minutes and covers your weight, training and nutrition adherence, steps, sleep, energy, hunger and stress. Your coach replies with written feedback, adjusts your plan when recovery is slipping, and you can message your coach directly if you are wondering where a plunge or a sauna fits.

If you want a plan built around how you actually recover, apply for coaching.