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'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.

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.

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.

Whether you lift light weights with lots of reps or heavy weights with few reps—so long as you push until you can’t do another rep—you’ll build muscle about the same amount.