This is called delayed muscle soreness, which means that it is normal for you to feel sore 24 hours after training. Usually it reaches its peak within 48 hours, and then it begins to recover gradually. Fully relaxing after training can alleviate this problem. In the end, the academic circles didn't give a standard answer, so I can't give you an answer. After this happens, reduce the intensity and amount of exercise or train muscles in other parts, and then strengthen the intensity of exercise when the pain is small. At the same time, pay attention to protein's supplement. Have a good rest. Well, corresponding to it is acute muscle soreness, that is, muscle soreness during or immediately after exercise. It usually disappears within a few hours after exercise.