Lifting heavier weights for nine weeks made young men stronger in a max lift test than lifting lighter weights, even when both groups worked until they couldn't do another rep.

Lifting heavy weights for 10 weeks makes you stronger, no matter how long you rest between sets or how many reps you do, as long as you’re lifting around 80% of your max.

If you're a healthy young adult lifting weights, lifting heavier weights (fewer reps) helps you get stronger faster than lifting light weights (more reps), but lifting medium weights works almost just as well as heavy weights — the difference isn't big enough to say for sure.

If you lift heavy weights (85% of your max) instead of light ones (30% of your max) for nine weeks, you’ll get stronger on exercises like squats and deadlifts—even if your muscles don’t grow any bigger than if you’d lifted light weights.

Lifting heavier weights (fewer reps) leads to bigger strength gains than lifting lighter weights (more reps), even if both are done until exhaustion.

Lifting heavier weights might help you get stronger a bit more than lifting lighter weights, but the difference is so small that we can’t be sure it’s real — it could just be luck.