For young guys just starting out at the gym, doing 1 set or 3 sets of each exercise gives about the same strength boost in the upper body after 11 weeks.

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.

If you're already fit and lift weights, doing way more sets (15–20 per muscle group per week) doesn't make you stronger faster—in fact, you might even gain less strength than if you stick to just 5–10 sets.

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're already experienced with weight training, doing 5 to 10 sets per muscle group each week builds just as much muscle and strength as doing 15 to 20 sets—so going over 10 sets won't give you extra gains.

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.