Why is muscle soreness less obvious after fitness?

This is because you have gradually adapted to it, so you don't feel sore. In fact, I think pain can be said to be a good thing or a bad thing, which is good for people who gain muscle. The way to increase muscle is to stimulate local muscles with heavy weight to achieve slight muscle tearing, and to increase the cross section of muscles through supplementary repair by protein, so as to achieve the effect of increasing muscle.