When trained guys do lots of reps, they feel more tired, weaker longer, and more stressed than when they do fewer heavy reps — even though their muscles are damaged about the same.

When you lift weights that get harder or easier as you move (like with resistance bands), your body reacts more strongly in the short term—your muscles get more tired, your stress hormones spike higher, and your cells show more signs of being worked hard—compared to lifting the same weight the whole time, even after training for 20 weeks.

More reps don’t break your muscles more than heavy lifts — but they do make you more stressed and tired right after.

Lifting heavy weights just a few times doesn’t stress your body as much right after as doing lots of lighter reps.

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.

You can make your workout feel harder and your muscles burn more by resting less between sets—but you can still lift the same total weight without getting weaker.