Sitting in a sauna is relaxing after a tough workout. Plus, the heat that a sauna produces helps soothe your achy muscles. You might think that's the only benefit of soaking up the intense warmth from a sauna – but there's growing evidence that saunas have additional health benefits.

Most homes in Finland have a sauna because the residents believe in the health benefits a sauna offers. To them, the experience of resting in a sauna is almost sacred and an experience they take part in for the mental and physical health benefits it offers. Can Americans learn a lesson from the Finnish?

Here's a benefit that may surprise you. Preliminary research shows that saunas may help with muscle building. Should you head for the sauna before or after a strength-training workout? Let's look at how saunas and hot baths might aid muscle development when you train.

Impact on Growth Hormone

You often hear bodybuilders talk about growth hormones in the context of bodybuilding. Growth hormone is secreted by the anterior part of the pituitary gland in your brain. You release the most significant amount of growth hormone during the deepest stage of sleep. That's one reason sleep is so vital for healthy body composition. Your pituitary gland also churns out more growth hormones in response to resistance and endurance training, especially when increasing exercise intensity.

What's so special about growth hormones? It aids in muscle growth and helps with the preservation of bone mass. Growth hormone stimulates muscle growth by its impact on a hormone called IGF-1. This hormone is made by the liver and turns on muscle protein synthesis. If you're trying to get stronger or build muscle size, that's what you want. Unfortunately, you produce less growth hormone as you age. This partially explains why people lose muscle and why it's harder to build muscle later in life.

You might wonder what this has to do with saunas. A study from 1986 showed that sitting in a dry sauna for one hour twice daily for seven days led to a four-fold increase in growth hormone release in women. It also stimulated growth hormone release in men. Since growth hormone through, IGF-1, aids in muscle protein synthesis, this works in your favor if you weight train. Remember, as we age, we naturally produce less growth hormone. Resistance training, combined with adequate sleep and sauna visits, could boost your body's growth hormone release.

Activation of Heat Shock Proteins

Sitting in a hot sauna places mild stress on your body as you expose it to more heat than it's accustomed to. In response, your body produces heat shock proteins. Other stressors such as infection, starvation, low levels of oxygen, toxins, and even exercise also trigger the production of heat shock proteins. Your body makes these proteins to help repair cellular damage that could occur in response to heat exposure.

In addition, these proteins activate your body's internal antioxidant defense system. This, in turn, can stimulate muscle growth. In animals, heat shock protein enhances the growth of muscle tissue. Heat shock proteins also make your body, including your heart, more resistant to stress, partially by reducing oxidative damage. So, along with potentially boosting muscle growth, heat shock proteins offer an added layer of protection against stress-induced damage.

Improvements in Insulin Sensitivity

Insulin sensitivity is vital for healthy body composition. When muscle cells are more sensitive to insulin, they take up amino acids and glucose more efficiently and don't require much insulin release. The muscle cells then use the amino acids to build new muscle tissue.

Greater insulin sensitivity helps better deliver muscle-building amino acids into muscle cells. Plus, greater insulin sensitivity makes you more resistant to gaining body fat. When you don't have good insulin sensitivity, your pancreas has to produce more insulin. As insulin floods your bloodstream, fat cells can't release fat stores as readily, and you hang on to stored fat.

The good news is that regular sauna sessions seem to improve insulin sensitivity. This is important for muscle development as it helps with blood sugar control. If you have diabetes, sauna sessions may be beneficial. However, always consult your doctor before using a sauna or taking a hot bath, especially if you have diabetes or heart disease.

Other Benefits of Sauna Sessions

Relaxing in a sauna may be good for the health of your heart as well. Studies show that heat enhances the release of nitric oxide from the inner walls of arteries. This improves blood vessel function, making the blood vessel more flexible and, in turn, lowering blood pressure.