Short answer: after, for most people, most of the time.

Longer answer depends on what you are training for and what you want out of the sauna.

After a workout: the default

Recovery. Increased blood flow to muscle tissue supports the recovery process. Most people report less stiffness the following day.

Heat adaptation. The heat exposure benefits, including plasma volume expansion and improved thermoregulation, come from the sauna itself and are not diminished by having trained first.

Growth hormone response. Some research shows a growth hormone spike from sauna use. Whether that meaningfully compounds with post-exercise hormonal response is unclear, and it is a plausible reason to stack them.

Practicality. You are already hot, already sweaty, already at the gym mentality. Going after is what people actually do.

Wait 10 to 20 minutes after finishing to let your heart rate come down and rehydrate before you get in.

Before a workout: narrower use case

As a warm-up. Raises tissue temperature, which can improve range of motion. Fifteen minutes maximum, then get moving.

Before mobility work or stretching. This one is legitimate. Warm tissue lengthens more readily, which is why assisted stretching after heat works well.

The problem: a long sauna session before hard training leaves you dehydrated and with elevated core temperature going into the workout. Performance drops and in Phoenix that is a real risk, not a theoretical one.

If you sauna before, keep it short and hydrate aggressively.

The strength training exception

This is worth knowing and it applies to the cold, not the heat.

Cold exposure immediately after resistance training may blunt some of the muscle-building adaptation. The inflammatory signaling that follows hard lifting is part of how the adaptation happens, and cold suppresses it.

So if your goal is hypertrophy or strength, do the cold plunge several hours after lifting or on a rest day. Sauna after lifting is fine.

If your goal is recovery between competitions or between hard endurance sessions, cold right after is a reasonable trade.

The Phoenix version of this question

In May through September the calculation changes.

If you trained outdoors in the morning, you already got substantial heat exposure. Adding a sauna session the same day is a lot of thermal load and you should be honest about your hydration status before doing it.

If you trained indoors in air conditioning, sauna after is fine.

Either way, drink before you get in. Sixteen to twenty ounces minimum, with electrolytes if you have been sweating a lot already. Coming into a sauna dehydrated is how people end up dizzy.

Session structure

Fifteen to twenty minutes for a first session, building to 30 to 45.

Three to four sessions a week is where most of the research clusters. Twice a week still helps.

Sessions start at $40. The $149 monthly membership includes daily sauna, cold plunge, hot tub, red light and compression, which is the sensible option if this is a routine.

Contrast option

Sauna, then plunge, then repeat. Fifteen minutes hot, one to three minutes cold, two or three rounds.

End on cold for alertness, end on heat if you are going home to sleep.

Who should ask a doctor first

Cardiovascular conditions, uncontrolled blood pressure, pregnancy, and medications affecting sweating or thermoregulation. Some blood pressure medications and antihistamines qualify.

Never after drinking.

Book a session

Reserve an infrared sauna session in North Phoenix.