If you lift lighter weights with only 30 seconds of rest between sets, your body might spike growth hormone and make your muscles look bigger right after the workout—more than if you lift heavier weights and rest for 3 minutes between sets, as long as the total amount of lifting is the same.

In guys who lift weights regularly, doing more reps with lighter weights and short breaks gives a bigger boost in growth hormone early on (by week 3) than doing fewer reps with heavier weights and longer breaks—but by week 10, that difference goes away.

Even though lifting weights with short breaks makes your body release more growth hormone, that doesn’t mean you’ll grow bigger muscles over time.

Lifting lighter weights with very short breaks between sets makes your muscles swell up more right after working out than lifting heavy weights with long breaks—so if you want that pumped feeling fast, go light and quick.

If two groups of young men lift weights with the same total effort but one rests longer with heavier weights and the other rests briefly with lighter weights, they both get just as strong after 8 weeks—even though you’d think the heavy weights would win.

If you lift light weights with short breaks between sets for eight weeks, your upper arms might grow bigger than if you lift heavy weights with long breaks—even if you do the same total amount of work. Light weights + quick rest = more muscle growth in this study.