If you want to exercise your muscles, you should exercise after running. If you want to lose weight, run after fitness. After running, there is a certain consumption of sugar in the body, and the energy consumption of white muscle is large. At this time, fitness can stimulate the red muscle to increase the fiber diameter (the number of muscle fibers remains unchanged), while the red muscle, which is in charge of explosive force, recovers energy faster than the white muscle and gets more effective exercise. To store more non-sugar energy. On the contrary, muscle tissue will be congested after fitness, and the diameter of muscle fiber (total muscle mass) will increase slightly, because the increase of muscle tissue will increase the consumption of calories, thus improving the efficiency of weight loss.