if your wanting muscles so that u hit harder...hitting the bag at a proper distance strengthens your punching power ..boxers to maintain there weight and speed try not to bulk up and "strength train" instead of try to thicken up w/ muscles

anyway its mainly doing lots of medium-light weight reps and u GRADUALLY through time can add more on your rips ...but you MAx out almost every other time u lift ....

this is opposed to pumping the heavy iron less reps


the 1st way i said helps keep your arm endurance along w/ speed and weight '
but if u wanna just get bigger and not just stronger then eat Large amounts of protein and keep doing the heavy lifting as heavy as u can get w/ most reps as u can get in your pyramid