Two: the main purpose of breathing is to provide the oxygen demand of the human body and eliminate the excess waste gas in the body. When the human body is resting quietly, it breathes about 10 to 12 times per minute, and the amount of each breath (tidal volume) is about 500ml, that is, when the human body is resting quietly, it breathes about 5 to 6 liters per minute. Although the amount of oxygen inhaled in the body is as high as 1000 to 1200ml per minute, 70 kg adults only use about 300ml of oxygen per minute. The air exchange capacity of human body during maximum exercise can reach 100 liter per minute (about 20 times that at rest), but the maximum oxygen intake of human body is only 3000ml per minute. This phenomenon that the exchange capacity of breathing increases and the utilization rate of oxygen decreases seems to indicate that breathing is not the main limiting factor of human endurance sports performance. Sufficient delayed intake can supply the body's needs and ensure the fitness effect.

Two: Breathe in through your nose during exercise. Breathing through the nose during running and cooperating with the fitness rhythm can meet the oxygen demand in the body. With the increase of fitness intensity, the oxygen demand increases, and the breathing mode of inhaling through the nose and mouth should be changed. Inhale and exhale slowly, thin and long, and open your mouth slightly when exhaling, so as to avoid quick breathing or big breathing. Shortness of breath and poor sense of breathing during exercise are due to insufficient exhalation and insufficient discharge of carbon dioxide, which occupies alveoli and limits the inhalation of oxygen. If you want to increase the expiratory volume, you must exhale through your mouth and consciously increase the expiratory volume and time.