Mainly because the metabolism of the body is accelerated after exercise, the secretion of hormones in the body is also increased, and nutrition sometimes cannot keep up, leading to hair loss.
I suggest you control your daily exercise. Don't make your body too tired. It is best to go to the gym every other day to let your body have an adaptation process. After a while, your body won't lose hair.
Keep exercising! Having a good body is good for all parts of the body.
Come on!