Lifting weights for three months can make the upper arm muscle about 13% bigger in young college guys.

After a tough bicep workout, your arm gets a little swollen, but it goes back to normal by the next day — and it doesn’t matter if you changed your shoulder angle during the workout.

Doing more biceps workouts each week might help build stronger, thicker muscles—even if the differences aren’t crystal clear in the data, it seems like more sets could mean better results.

Lifting weights for three months didn’t increase the number of muscle fibers in young guys’ biceps, so their muscles got bigger without adding new fibers.

If you're a young guy who already lifts weights, doing twice or three times as many sets per week won't noticeably grow your biceps more over six weeks — even if there's a small trend toward more growth.

Lifting weights for three months makes the muscle fibers in young men's biceps get bigger — both the endurance-type and power-type fibers.