For many years, I have always liked to relax in the sauna, especially in cold weather. But last summer, I was surprised to see a doctor friend of mine coming out of the sauna in hot July and then going to exercise. Before he got to the gym, he was sweating like a pig.

My friend explained that it becomes more and more important to warm up muscles, tendons and joints before strenuous exercise with the increase of age. Although 10 minutes of warm-up exercise on an exercise bike or treadmill may be a traditional way to warm muscles gently, sauna really warms muscles and prepares them for exercise. This caused my buzz, because in the past few years, I felt pain in my achilles tendon every time I ran. I have been treated by several doctors, and their prescriptions are stretching, putting heel pads in sports shoes and even bombarding my achilles tendon with sound waves-the effect is not lasting.

After talking to my doctor friend, I found a study on the benefits of sauna for athletes. Although the study is quite small, it found that these athletes only need to steam in the sauna for half an hour before high-intensity running, and they can run further before they are exhausted.

The researchers concluded that the most likely explanation was that sauna training increased the plasma volume of athletes.

Now any cyclist knows that you can improve your aerobic exercise ability by increasing the amount of hemoglobin. The function of hemoglobin is to transport oxygen from the lungs to all parts of the body. This is why people who cheat in bicycle races will lose their blood back to themselves. This practice is called "blood stimulant".

But what interests me is that I learned that sauna may also improve the secretion of a series of hormones, including growth hormone and norepinephrine. The latter regulates the so-called "fight or flight" response and increases blood flow to skeletal muscle.

My original intention is to see if sauna can improve my sports performance as mentioned in the above research. I tried to steam in the sauna room for half an hour before running according to the prescription studied above, but I felt too hot to run at all. So I changed to a sauna after running. At first, I could only stay in the sauna for 10 minutes.

In the past six months, I have slowly extended the sauna time. Now, I do a 30-minute sprint twice a week and then steam in the sauna for 20 minutes. When you are in the sauna, you really sweat, which should help train your body to sweat more effectively and lower your body temperature when you exercise.

To my surprise, my achilles tendon pain disappeared after I started sauna therapy. There is an added benefit, that is, the knee pain I felt after carrying out weight-bearing exercise on the leg press suddenly disappeared.

I even feel that my sprint performance has improved, but the reason may be more regular training.

An important warning: Although it is generally believed that sauna is safe for most athletes, people with heart disease or pregnant women should consult their doctors before trying it. Drink plenty of water before and after the sauna to make up for the sweat and water loss caused by the sauna, and the time of each sauna should not be too long. Of course, never drink alcohol before or during the sauna.