If you're a guy who already lifts weights regularly, doing too few or too many sets won't make you stronger the fastest — the sweet spot is around 5 to 10 sets per muscle group, and doing 15 to 20 might actually help less.

If you're already fit and lift weights, doing anywhere from 5 to 20 sets per muscle group each week will make you stronger and build more muscle — and it doesn't matter much which number you pick within 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.

The more you lift weights (up to a point), the more muscle and strength you gain—and new studies say it’s a steady climb, not a peak and drop like we used to think.

When you lift weights, how much total work you do matters more for getting stronger and bigger than whether you use heavy weights with few reps or light weights with many reps.

Doing 14 sets vs. 21 sets doesn’t make your muscles look any different on ultrasound—even though you lifted more total weight in the 21-set version.