Lifting weights until you can't do any more reps makes your muscles grow just as much, no matter how heavy or light the weights are.

When you train hard enough to fail on every set, how heavy the weights are matters less than your body’s natural ability to grow muscle.

Whether you lift heavy weights for fewer reps or light weights for more reps—as long as you push until you can’t do another rep—your muscles grow about the same amount.

Whether you lift heavy weights with fewer reps or light weights with more reps—as long as you push until you can’t do another rep—your muscles grow about the same amount.

When people lift weights until they can't do another rep, their muscles grow about the same amount whether they use heavy or light weights — and how much they grow depends more on their own body than on how heavy the weights are.

When healthy young men lift weights until they're too tired to continue, their muscles grow about the same amount in both their arms and legs, no matter how heavy the weights are.