Work them legs............if you wanna grow
 

Work on your legs if you want to grow your upper body

This may look confusing, but think about it, why you should train your legs? Almost 70% of your muscle mass is in your legs. Training them will help you grow all over. Like I mentioned before – doing squats and deadlifts will trigger the release of anabolic hormones that will help you develop other areas, not just legs.