Whether you use machines that change resistance as you lift or keep the same weight all the way through, after 20 weeks of training, healthy men gain about the same strength and muscle size either way.

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 new to lifting weights, whether you switch up your weights and reps (variable training) or stick to the same routine (conventional training), you'll build muscle at about the same rate—neither method is better than the other for getting bigger muscles in the first few months.

Doing varied weight workouts might hurt your muscles a little less than doing the same routine over and over—but you still gain just as much muscle, meaning you don’t need to feel wrecked to get stronger.

If you're a young guy lifting weights more often each week, you'll likely get stronger faster—but that doesn't mean your muscles will get noticeably bigger.

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.