Side planks are a great way to work your core, but why not add a twist to spice things up? Adding any kind of motion to a side plank challenges your balance, works your obliques, and tones your shoulders. Needless to say, it's a move you have to try!

• Start in side elbow plank on your right side, with your feet stacked one on top of the other. Keep your weight on your right elbow with your fingers reaching away from your body.
• Place your left arm behind your head, and inhale to prepare.
• Exhale, and pull your navel to your spine and engaging your deep abs. Rotate your left ribcage toward the floor, bringing your left elbow to your right hand.
• Return to the starting position to complete one rep.
• Do 10 reps on each side.

Bonus: although this is a strength-training move, this exercise also provides a nice stretch for your upper back!