Only by striding can you run fast, swinging your arms back and forth can you save effort, and you can't stop running fast. Can stride, land lightly, bend your arms and swing back and forth. No defects such as left calf and splayed foot. Mastering the methods of running in circles, running back and forth, taking things and relaying can better control the running direction and adjust the running speed. Running 20 meters in a straight line is not slower than 6.5 seconds.