Are 20lb dumbbells good for me?
I'm 15, 5 foot 5 and weigh 101lb. I started lifting 10lb dumbbells for 1 hour but I thought I could lift more. So I stepped it up to 20lb because the store rep. said that lifting hevier weights and less reps. build muscle while lifting lighter weights with a lot of reps. would just tone. I can do about only like 5 reps. with the 20's. Is what he was saying true?