Before fitness, you should relax and mobilize your body. For example, move your knees and wrists and stretch your arms. You can download a fitness software "keep", which has a very detailed tutorial.
When stretching, you should move your whole body. The broadcast gymnastics we usually do is a very good body stretching exercise. You can try it. Then, move all the joints of your body, especially the knee, wrist and ankle.
Some stretching exercises can be done, such as side leg press, lunge leg press, knee lift and butterfly step, which can all be used as sports stretching. Before running down, it's best to run for a while, so that your body can get used to it and move completely.
After exercise, don't sit down or rest immediately, and finally walk for a while to adapt your body. Then pat the thighs and calves. At this time, you can also use some leg press exercises to relax.