HOW: Start by positioning yourself laying on a swissball in between your chest and stomach. Your knees should be straight out with your toes pushing into the ground. Have a weighted ball in each hand and extend your arms up overhead to make a “Y” position. While keeping your body still, bounce the ball up and down by slightly dropping it and catching it right away.
FEEL: You should feel your shoulder muscles working.
COMPENSATION: Keep your knees off of the ground. Don’t arch your back, stay as straight as you can.