Even doing a huge number of leg sets—over 50 a week—didn’t make anyone’s muscles shrink, which means there might be a very high limit to how much training your muscles can handle without losing size.

Doing a lot more leg workouts—over 50 sets a week—doesn’t make your thigh muscles grow bigger than doing 20–40 sets a week, even if you train for 12 weeks.

If you're already fit and lift weights, doing 5 to 20 sets of exercises for each muscle group every week won't make you grow bigger muscles any more or less than any other number in that range.

If you're already used to lifting weights, training until you can't do another rep gives you about the same muscle growth as stopping a few reps short—so you don't have to push to absolute exhaustion to build muscle.

Even though the guys doing the most workouts looked like they might have grown a little more, the difference wasn’t big enough to say for sure that more sets = more muscle.

Even though guys doing drop sets did only one set instead of three, their muscles grew just as much or more than those who did three sets.