It is easier to learn to swim when you are young, because children accept it quickly. Don't swim too long. Swimming for too long is not only unacceptable to the body, but also will not bring us much swimming effect.
Generally speaking, the swimming time should not exceed 1.5-2 hours, which is determined by the three reaction periods of skin to cold stimulation.
The first stage is after entering the water, stimulated by cold, the skin blood vessels contract and the skin color is pale.
In the second stage, after staying in the water for a certain period of time, the blood flow on the body surface expands, the skin turns from pale to reddish, and the skin turns from cold to warm.
In the third stage, if you stay too long, your body temperature will dissipate more than your fever, and your skin will get goose bumps and chills.