If young men lift light weights with very short breaks between sets for 8 weeks, their upper arms grow more than if they lift heavy weights with long breaks—even if they do the same total amount of lifting—because the short breaks create more muscle-burning stress that helps muscles grow bigger.

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.

If you're a young man who already trains regularly, doing more sets with lighter weights for 6 weeks can make your thigh muscle grow a little bigger — but doing fewer sets with heavier weights won't make it grow at all.

If young men lift weights with the same total effort—whether they use heavy weights with long breaks or light weights with short breaks—they’ll still grow about the same amount of muscle. So, different ways of lifting can both work.

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 weights with either light weights and short breaks, or heavy weights and long breaks—but keep the total work the same—you’ll still build muscle in about 8 weeks. So, there’s more than one way to get stronger and bigger muscles.