When young adults train really hard until they can’t do another rep, it doesn’t matter whether they’re working their arms, legs, or doing squats vs. bench presses — the results for muscle growth and strength stay pretty much the same.

If you're already experienced with weightlifting, pushing your muscles to failure might help them grow bigger—but if you're new to lifting, doing the same thing doesn't seem to give you the same benefit. Your experience level changes how effective this technique is.

If you lift weights until you can't do another rep, you might build more muscle than if you stop before reaching that point—but we’re not totally sure yet.

If you lift weights until you can't do another rep or stop a little earlier—but do the same total amount of work—your muscles will grow and get just as strong either way. So you don’t have to push to absolute failure to see results.

If you lift weights until you can’t do another rep or stop before that—as long as you do the same total amount of work—you’ll get just as strong either way. You don’t have to push to absolute exhaustion to build strength.

When lifting lighter weights, pushing until you can't lift anymore helps build bigger muscles, but this doesn't happen with heavier weights. Heavier weights always build more strength than lighter ones, no matter how hard you push.