Chest muscles have no strength, so do push-ups first, and then practice flying birds easily after 30. Birds can practice contours and inner sides, but if they simply increase muscles, push iron. But the muscle density of unarmed exercise is better than that of pushing iron, and the lines are more harmonious and beautiful. I have been exercising with my bare hands, and my muscles are not very big, but my explosive power is much stronger than pushing iron.