The exercise ball dumbbell extension is the same as a one arm seated dumbbell extension,but you're seated on an exercise ball. The ball makes your core work harder to maintain stability. Set up by sitting on an exercise ball with your feet firmly placed on the floor holding a dumbbell above your head with your left hand, thumb facing your head (palm forward).

Use your other arm to help stabilize the body on the ball.

Tense the mid section and straighten the lower back. This is the starting position for the exercise.

Keeping your eyes facing forwards and elbow locked in position, slowly lower the dumbbell behind your head as far as possible.

Pause, andthen raise the dumbbell back to the starting position without locking your elbow out.

Lower and repeat for desired reps, and then repeat the same process for your right arm.

Exercise Tips:

As a general rule always work your weakest arm first.In most cases this will be the left.

Keep the core muscles tight during the set to assist in keeping your back straight.

The elbow must remain fixed above the head.Don't allow it to move as you lower and raise the dumbbell.