Lifting lighter weights many times until you can't do more improves muscle endurance better than lifting heavy weights just a few times, especially for people who already work out.

Whether you lift heavy weights for a few reps or lighter weights for more reps until you can't do any more, both ways make your thigh muscles grow about the same amount in people who already work out.

Lifting heavy weights for just a few reps makes you stronger in exercises that work one muscle at a time, more than lifting lighter weights for many reps, especially if you already work out regularly.

Lifting lighter weights many times in a row helps well-trained young men do more push-ups longer than lifting heavier weights fewer times, after 8 weeks of training.

Using light weights until you're exhausted or slow builds your muscle stamina better than heavy weights, but doesn't make you as strong as lifting heavy weights.

When people lift light weights until they can't anymore, their thigh muscles grow much more than if they just lift lightly without pushing to the limit, showing that working really hard is key for muscle growth even with light weights.