According to your current body, you can't keep up because you haven't practiced high intensity for a long time. Even if I have a better way, it is not suitable for you, and my body is particularly vulnerable.
I suggest:
Flexible thigh lacing helps to lift legs quickly and warm up (actually lacing). Both the outer thigh and the front thigh can be solved on stairs or high buildings.
Sir, you can do quick leg lifts. It's best to tie it to a building such as a tree or a pillar with a leather rope, and then tie the other side to your waist for 30 seconds. Do three groups respectively and lift your legs as fast as you can.
Third, 100 meters is very important. You must practice breaststroke. You must squat down all your legs and jump forward quickly. 12 Jump into a group and make three groups. Then you jump in the same place. That is, you can jump up with your head in your hands and squat down in succession. Group one and group three jump faster. )
Fourthly, technically, since I can't teach you personally, I suggest you find a video to teach the swing arm. Remember to keep your palms facing each other. Don't make a fist, it will become a dead strength. There is also running with a straight waist and abdomen and a relaxed upper body. Running is running with your feet, not your hands. When your body is tense, it will only become dead strength and form obstacles.
Summary: First of all, I realize that the speed of running is simply the two most important factors. First of all, the speed of leg lifting is what we call frequency, and then the strength is explosive power and high-frequency endurance. High-frequency endurance is how long you can hold on to extremely fast leg lifts, so I emphasize that you should practice leg lifts, which will definitely help you recover. I wish you good grades. If you think it is good, don't forget to adopt it. Oh, if you understand, you can also ask thank you.