The first is the issue of race. European and American races are naturally stronger than yellow races. Secondly, it is because of diet. Europeans and Americans like to eat high-protein foods such as beef, and muscle synthesis just needs high protein. Finally, the problem of fitness. Europeans and Americans love fitness, which is relative. Some people don't. Compared with people in our country, it is common to invite a few people to play ball games or go to the gym to exercise their muscles after work. This is like our usual date.