In nature, no animal wants to run in the big sun except being forced to be attacked or hungry to hunt. Hot weather is not suitable for running, and few animals in the animal kingdom are willing to hunt in hot weather. People's long-distance running ability in nature is unparalleled, but there are still many unsuitable places for running at high temperature. High temperature does damage the running combat effectiveness from many angles.
High temperature, blood flows to the skin, muscle blood supply decreases, and fatigue is more likely. Dazzling sunshine is easy to cause psychological anxiety. Sweating consumes energy and raw materials. When the temperature is higher than 35 degrees, the human body can only rely on sweating to dissipate heat, and other methods such as convection and thermal radiation have no effect. When running, you have to sweat a lot and consume energy. Sweating also requires water and salt (mainly sodium ions, and a small amount of calcium and potassium). Minerals such as sodium, calcium and potassium will be lost with sweat and affect the internal environment of the body. Therefore, in order to balance this loss, it is necessary to supplement salt or sports drinks.
In addition, wearing a hat in summer also needs to pay attention to heat dissipation.