If a young, healthy man lifts weights for 8 weeks, his muscles will likely get bigger—by about 6%, give or take a little.

Using machines or bands that change how hard they feel as you move might make your muscles work more evenly during an exercise, but that doesn’t always mean you’ll grow bigger muscles faster than with regular weights—especially if you’re just starting out.

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.

Higher weekly resistance training volume leads to greater muscle hypertrophy in trained individuals.

If healthy guys between 18 and 40 lift weights regularly for at least two weeks up to a year, they typically gain about 1.5 kilograms of muscle—no matter what kind of weight routine they follow.

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.