Say I give you a backpack with 10 pounds in it and tell you to run down the track. You’ll move slower than you would have without the weight, right? Well, bulking up your pecs has the same effect as the backpack, which is why my sprinters aren’t allowed to bench press. They only do bodyweight exercises for their upper bodies, such as fingertip push-ups. These strengthen your hands so you’re more stable when starting from the blocks. – Ken Harnden / Florida State University / Sprints coach