Because of lack of exercise. After exercise, capillaries will relax, which not only promotes the growth of muscle fibers, but also burns fat and produces lactic acid.

Under normal circumstances, the pain will gradually disappear. If you don't warm up well before exercise, the pain will last for a long time, and you may even get hurt.

If your pain is not serious, you can apply a hot towel to your calf. You can continue to exercise the next day, but you must warm up in advance.

If you feel serious, you should immediately stop exercising, fully massage and apply hot compress. Wait until you feel you can bear it, and then resume exercise.

If you suspect a muscle or tendon injury, you should wait until the injury is completely healed before exercising.

My experience is that muscle strain does not need medical treatment.

Whether the landlord wants to become a muscle or not, whether it is fitness or bodybuilding, warm-up before exercise and massage after exercise are very important and must not be omitted.