Lifting weights until you can't do another rep leaves you much more tired during and after the workout than stopping a few reps short — even if both methods build muscle equally.

If you lift weights until you literally can't do another rep, you'll feel more tired right after than if you stop a couple reps before failure — even if you're someone who regularly lifts weights.

If you lift weights until you can't do another rep, or stop just before failure, your thigh muscles grow about the same amount after eight weeks — but stopping short feels less exhausting each time.

If you lift weights until you can’t do another rep versus stopping before failure—while doing the same total amount of work—you’ll feel more tired and more worn out during the workout, especially if you’re a regular gym-goer.

Stopping a few reps short lets you do about the same total amount of work over weeks as going all the way to failure — because you can recover faster and do more sets without burning out.

Doing 8 weeks of strength training with your muscle either stretched or bunched up doesn’t make you much better at resisting fatigue — the improvement is very small and not clearly real.