If you work out more often, your muscles grow bigger — but only if you keep increasing your workouts, because your body gets used to the same routine and stops responding as well.

If you’ve been lifting for a while, doing more workouts over time will help you build more muscle than just lifting heavier weights.

The total amount of work done (weight × reps × sets) seems to matter for muscle growth — more work generally leads to more muscle, even if the weights are light.

For older people, doing four sets of weight exercises instead of just one can help build more muscle—but only if their body is already somewhat responsive to exercise; if it’s not responsive at all, more sets don’t help.

If you're already used to lifting weights, doing more sets and reps over time will help you build bigger muscles and get stronger — but only if you keep training consistently.

Doing more sets in a workout helps you get stronger and bigger, but after a certain point, extra sets don’t help much—especially for strength. You hit your sweet spot for strength with fewer sets than you need for muscle growth.