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.

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 experienced with weight training, doing 5 to 10 sets per muscle group each week builds just as much muscle and strength as doing 15 to 20 sets—so going over 10 sets won't give you extra gains.

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.

Doing drop sets (lifting heavy, then lighter weights without resting) builds muscle just as well as doing regular sets with longer breaks, at least in young, experienced lifters.

After 10 weeks of hard lifting, your arms only get a tiny bit bigger — less than the thickness of a penny — no matter which method you use.