Why is the eight-character brake in skiing?

Squat down in the process of sliding, choose a steep terrain to slide down, and accelerate with a pole. You can use the inner eight characters to slow down. But if the speed is too fast, you can't slow down like this. Sideslip deceleration should be used. In the process of sideslip, the upper body keeps upright, the knees are pushed to the mountain side, the two skis keep parallel, and the ski on the mountain side protrudes slightly forward. The snowboard on the lower side of the mountain bears the weight and gets stuck on the snow surface after standing on the edge.