Originally Posted by Pen2AndyP

I tried 3 lbs for awhile, that's a bit too much, my arm hyperextended too much, and my technique got sloppy for about a week, I wouldn't do it, terrible arm pain, with no helpful results, you can use 3 lb dumbells and work on your stance to build arm stamina, but not shadowboxing. You'll sprint faster on the road than on a treadmill too. Roadwork beats treadmill by far because you go at your own pace, you can pratice turns and slips better by dashing, and there is incline.