In long-distance running, we should swing our arms and focus on training trapezius muscle, rhomboid muscle and serratus muscle.
The leg-crossing action mainly trains gluteus maximus, posterior thigh muscle, quadriceps femoris, triceps femoris and posterior tibial muscle. There is little training for abdominal, chest, back and neck muscles. Long-distance running can maintain a normal lean weight, because most of the time you are doing aerobic exercise, which consumes fat completely, but if you want to keep your muscles fit, you'd better do fitness exercise. Although long-distance running has also exercised some muscles, it is not conducive to muscle shaping because of its high energy consumption.