After deep inhalation or shallow inhalation, close the glottis and try to exhale. This is called holding your breath. It is usually necessary to hold your breath when completing the maximum static exercise, such as carrying weights, lifting weights, wrestling, tug-of-war, "arm wrestling" and so on. Holding your breath has a good effect on exercise: holding your breath can reflect the increase of muscle tension and create the most effective contraction support conditions for related sports links. However, people only see the beneficial side of holding their breath, and they don't know that holding their breath will have a negative effect on the human body. The adverse effects of holding your breath mainly include: First, holding your breath increases the internal pressure in the chest cavity, which hinders the venous blood return, and then the heart is not fully filled, the output drops sharply, and the blood pressure drops sharply, resulting in insufficient blood supply to the myocardium, brain cells and retina, resulting in dizziness, nausea, tinnitus and blackness in front of your eyes, which affects and interferes with the normal exercise; Second, at the end of breath-holding, there will be reflective deep breathing, which will cause the pressure in pleural cavity to drop sharply. The blood originally trapped in the vein will quickly return to the heart, impact the myocardium, make it overstretched, and the blood pressure will also rise sharply, which will have serious adverse consequences for children's hearts, easily make the myocardium overstretched and relaxed, and for the elderly, it will easily damage the blood vessels in the heart, brain and eye due to poor blood vessel elasticity and brittleness.

From this perspective, holding your breath has advantages and disadvantages for exercise. Sometimes you need to struggle and hold your breath to win the final victory. Then the necessary and correct and reasonable way to hold your breath should be not to inhale too deeply before holding your breath; In order to gradually reduce the internal pressure in the pleural cavity, the exhaled air should gradually squeeze out of the glottis slightly and moderately, that is, the larynx exhales with a "hi" sound; Hold your breath in the critical moment of winning the game, not every movement and every process needs to hold your breath.

Suicide without holding your breath.

The breathing of the human body can also be controlled by the will. However, if you deliberately hold your breath for too long, it will lead to a decrease in oxygen concentration in the blood and an increase in carbon dioxide concentration. At this time, people will gradually fall asleep and their willpower will weaken, so the mechanism of brain stem automatically controlling breathing will start, and finally the concentration of oxygen and carbon dioxide in blood will return to normal.