When you think of core training everyone usually thinks of a girl doing some type of exercise on a stability ball, or a plank or pillar bridge of some type. What people fail to realize is that the best core training comes from resistance training with dumbbells, kettlebells or barbells where you are standing. This requires all of your stabilizer muscles to fire just to keep you standing straight while performing the exercise. I started doing heavy (what else) dumbbell overhead press for core training and shoulder training. Dumbbells are much harder to stabilize with (for me) than kettlebells. I started with 50lb dumbbells and have worked my way up to 70lb dumbbells as you can see in the video. It takes every fiber of my being to stabilize with a 70lb dumbbell in each hand. It works everything from head to toe and is very effective. I encourage everyone to try lifting while standing instead of being seated. Sitting while lifting takes alot of the stabilization effort out of the lift and allows you to lift even heavier. Anyway, this shows that you don't need to bounce around on a ball to work your core. It's only too heavy if you can't lift it and as always "Go heavy or Go home".