This is quite a simple question. Sports will of course affect how muscular you are, but if you do not play a sport ( or a sport that does not involve working the muscles) try lifting weights and consuming adequate amounts of protein, amino acids ( two of the many building blocks of muscle ) and carbohydrates. Good sources of protein include lean red meat and of course protein supplements.
excerice
no
There are lots of fun ways to gain muscles by playing outside! Simply by playing sports, and running around you can gain some strength. If you are looking for significant muscle growth, I would suggest choosing an athletic activity that you enjoy, and working on isolating those muscles. For example, if you love playing football, focus on improving the muscles that you use the most in football.
The lower the weights, the stronger and leaner your muscles will become with more repetitions. If you want bigger muscles, you should try heavier weights.
Squats, swimming, wall sits
Some good ways to strengthen your knees would be to perform exercises which would strengthen the muscles around your knees. Low impact sports would help to build muscles on your knees as well.
Lift weights with them
milk
poseidon
bigger muscles
i don no
The gymnast have more muscles but the foot ball player has bigger muscles.