If you're a guy who lifts weights and stops just before your muscles give out, you'll do fewer reps and lift less total weight than if you go all the way to failure — but you'll still gain just as much muscle and strength. That means pushing close to failure might be a smarter, more efficient way to train.

If you're lifting heavy weights and stop just before your muscles give out, you'll still gain about as much muscle as if you pushed to the very last rep you can possibly do.

For beginners lifting weights, pushing muscles to complete exhaustion doesn't build more muscle than stopping just short of exhaustion, as long as the total amount of lifting is the same over 8 weeks.

Lifting heavy weights until you can't lift anymore makes young male athletes much stronger than lifting light weights over 8 weeks, even if both make muscles grow about the same size.

When people lift light weights until they can't anymore, their thigh muscles grow much more than if they just lift lightly without pushing to the limit, showing that working really hard is key for muscle growth even with light weights.

If you lift weights until you can’t do another rep—whether you use heavy weights or light ones—you’ll end up with about the same muscle growth after nine weeks, as long as you’re putting in the same effort and number of reps.