When lifting lighter weights, you need to push until you can't do any more reps to build as much muscle as lifting heavy weights. But with heavy weights, you can build a lot of muscle without pushing to total exhaustion.

You can build muscle just as well lifting light weights as heavy ones — as long as you push yourself until you can’t do another rep.

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 and lifting lighter weights both build muscle about the same amount in healthy adults, as long as you do enough reps until you can't lift anymore.

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.

Lifting weights until you can't lift anymore makes muscles grow bigger no matter how heavy the weights are, but using heavier weights builds more strength than lighter ones.