When you do strength training, your body gets better at building the proteins that make muscles strong, while cutting back on making other less important proteins. It's like your body learns to focus on what really matters for muscle power.

Lifting weights at a challenging level makes your muscles build more protein, and this boost happens just as much in arms or legs that are used to exercising as in ones that aren't.

If you do lots of reps with lighter weights for six weeks, your body might make more of the non-muscle proteins inside your muscles than if you lift heavy weights with fewer reps — and this difference is pretty big.

Doing a tough leg workout with lots of sets makes your leg muscles start building new proteins much faster—2 to 3 times more than usual—right after the workout.

When young men lift weights to build muscle, their muscle-building process speeds up at first but slows down after 10 weeks, even if they keep increasing the difficulty.

Your muscles make more protein at first when you start lifting weights, but after a few weeks, that boost fades—even if you keep lifting harder.