Lifting heavier weights (60-80% of your max) makes you stronger than lifting lighter weights, even if you do the same total amount of work, especially after 12 weeks of training.

Lifting weights at different effort levels all help men get stronger and build bigger muscles after 12 weeks, but using the lightest effort isn't as good as pushing harder.

Lifting weights at different effort levels (from light to heavy) all made muscles bigger and stronger in men over 12 weeks, but the lightest effort wasn't as good as heavier ones.

Lifting heavier weights with proper form was better than lifting lighter weights for building both muscle strength and size in men after 3 months of training.

If you lift the same total amount of weight, lifting heavier weights (80% or more of your max) makes you stronger in a single big lift than lifting lighter weights—but lifting very light weights and light weights (under 60%) give you about the same strength gains.

If guys who already lift weights increase their workout volume by 30%, they’ll last longer before getting tired compared to doing the same amount or doubling up—after 8 weeks, they can do about 5 more reps before failing.