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.

Lifting heavier weights for fewer reps makes your legs much stronger than lifting lighter weights for more reps, but both types of training help your upper body a little bit too, and this might work differently for different muscles.

Lifting heavier weights for fewer reps makes well-trained young men stronger faster than lifting lighter weights for more reps, especially in exercises like squats and bench presses.

Lifting weights until you can't do any more reps, whether with light or heavy weights, makes muscles grow bigger in fit young men after 8 weeks. It shows that pushing to your limit is what really matters for growth, not how heavy the weights are.

Lifting lighter weights many times in a row helps untrained young men build more muscle endurance than lifting heavier weights fewer times. After 8 weeks, they can do more reps before getting tired.

Lifting heavy weights fewer times, three days a week for a month, helps young active men build more muscle and get stronger than lifting lighter weights many times.