You’ve probably heard that sauna can support recovery. But if your goal is to build muscle, reduce soreness, and get stronger, when you use heat matters just as much as how you use it.

Let’s break down what the research suggests — and when heat or cold may make the most sense around your training.

Every workout creates small amounts of stress within your muscles. That’s intentional.

Strength doesn’t happen while you’re lifting weights. It happens afterward, when your body repairs those microscopic changes and adapts by becoming stronger.

One of the most immediate effects of sauna is increased circulation.

As your body warms, blood vessels dilate and blood flow increases. This can support circulation to tissues during the recovery period after exercise.

Repeated heat exposure has also been associated with increases in heat shock proteins — specialized proteins involved in helping cells respond to stress and supporting cellular repair.

Some studies have also observed temporary increases in growth hormone after sauna exposure. These short-term hormonal changes should not be viewed as a shortcut to muscle growth, but they may be part of the broader physiological response to heat.

Cold exposure can be useful when the goal is reducing perceived soreness, cooling down, or feeling refreshed after hard training.

However, if your primary goal is maximizing muscle growth, research suggests that immediate cold-water immersion after resistance training may blunt some of the cellular signaling associated with muscle hypertrophy.

This article is for general educational purposes and is not medical advice. Individual responses to heat and cold vary. Consult your healthcare provider if you have a medical condition or questions about whether sauna or cold exposure is appropriate for you.