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.

When lifting lighter weights, pushing until you can't do any more reps helps build more muscle than stopping early. But with heavier weights, pushing to failure doesn't give much extra muscle growth compared to stopping a bit sooner.

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.

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.

If you lift weights until you can’t do another rep, your muscles will grow about the same no matter how heavy the weights are—but you’ll get stronger faster if you lift heavier weights.

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.