Fighting is mainly about practicing the explosive power of muscles, which can provide high instantaneous speed. Boxers are muscular, but not very big, just as Bruce Lee is not the muscular man people remember.

If you are thin, the instantaneous high-intensity exercise will have a strong stimulating effect on your muscles. Coupled with reasonable and sufficient nutritional supplements, your muscle latitude will rise, but if you keep practicing, your muscle growth will slow down. It will definitely grow slower than fitness, but it will become more and more exquisite, just like carving. Fighting is very good if you don't pursue that clumsy and bulky muscle. I met two boxers in the gym, but look.

Take two animals for example. They fight like frogs and exercise like toads. Toads are big and strong, while frogs are quick and fast.