In this variation, the abs work extra hard to maintain stability as you pull the dumbbell away from your centre.
- Begin sitting with your heels planted about two feet from your butt, holding the weights at chest level with a slight bend in your elbows. Lean back a few inches, pulling your abs toward your spine.
- With your left arm remaining still, open your right arm to the side, making sure the weight doesn't go beyond your shoulder.
- Bring your right arm back to centre to complete one rep.
- Switch sides, and do the same number of reps on each side.