When you tire out a muscle with one exercise before doing a bigger workout, you can't do as many reps in the big workout, so you end up doing less overall exercise than if you just did the big...

When you do a special workout called pre-exhaustion, you get tired faster and end up lifting less total weight compared to regular workouts.

When people who don't exercise regularly get tired out before doing certain workouts, they can't do as many repeats afterward—about 25% fewer.

Doing a special warm-up before lifting weights lets you finish your workout faster while still building just as much muscle.

Doing single-muscle exercises first makes you tired, so you can build muscle with lighter weights on bigger exercises.

Doing a light warm-up set before lifting heavy weights might help you build more muscle and get stronger, according to some research that tried a similar but different approach.