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.

If you lift light or heavy weights but do the same total amount of work, your muscles grow about the same amount—whether you're using light dumbbells or heavy barbells.

Total training volume, training intensity, and consistency are more significant determinants of muscle hypertrophy than the specific muscle length at which training occurs.

If you lift light or heavy weights but do the same total amount of work, your muscles grow about the same amount—so lifting light weights can be just as good for building muscle as lifting heavy ones.

Doing more sets at the gym than you're used to—like going from 18 to 33 sets a week per muscle group—doesn’t make your muscles grow significantly more, even though you might see a little more growth overall.

Everyone’s body responds differently to workouts—what works wonders for one person might be too much or too little for another, because of differences in genes, energy use, and how fast they recover.