Effects of resistance training performed to repetition failure or non-failure on muscular strength and hypertrophy: A systematic review and meta-analysis

If you lift weights until you're almost too tired to do another rep, you'll likely build bigger muscles—but your strength gains won't be any better than if you stopped earlier, as long as you're doing the same total amount of work and lifting the same weight.

Going all the way to exhaustion on every set probably doesn't build more muscle than stopping a few reps short — both seem to work about the same.

Going all the way to muscle failure during weight training makes you way more tired—both mentally and physically—but doesn’t help you build more muscle than stopping just short, so it might not be worth the extra effort.

If you push your muscles until they can't do another rep, you create more force per set—which can help if you're not doing many sets, but might hurt your progress if you're already doing a lot of work.

If you lift weights without pushing yourself to total exhaustion, you might get stronger faster—especially if you end up doing more total lifts overall compared to people who do go all the way to failure.

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.