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'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're someone who already lifts weights regularly, pushing your muscles until they can't do another rep might help you grow slightly bigger muscles than if you stop before reaching failure.

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.

Lifting weights until you can't do another rep doesn't help you build more muscle than stopping before you hit total exhaustion—so you don't need to push yourself to the absolute limit to get the best results.

Lifting weights until you can't do another rep won't stop your muscles from growing bigger, and it's probably safe to do—even if you're doing the same total amount of work as someone who stops short of failure.