In fact, it doesn't matter much, as long as you are comfortable and don't interfere with your movements. Dispel sweat, cool, and have an advantage when doing endurance. Tightness (especially functional clothing, not just small size) has a certain protective and boosting effect on muscles, and it will definitely be more refreshing when doing strength.

But there is one exception-a fat, shaky buddy, wearing tight clothes and tying the meat. The popular view is that the vibration of exercise will damage the joints. Similarly, it is necessary for girls to have a pair of tight underwear when they exercise.