Before attempting this abs workout from Men's Health, make sure you're loose and start off light before increasing the weight. This "dumbbell double wood chop" exercise is a more advanced one, so be careful… start off light.
Hold a light dumb-bell with a hand over hand grip, your arms extended above your left shoulder. Keeping your arms straight but not locked, bend at the knees and forcefully rotate your torso to the right as you draw your arms down and across your body.
When your arms reach the outside of your right ankle, pause, then quickly reverse the movement with the same intensity, pausing at the top. That's just one rep. Go for your prescribed number of reps, then hold the weight over your right shoulder and repeat the move, this time chopping towards your left ankle. By accelerating, rotating and decelerating you work your core muscles in a much more varied way.
As with all advanced exercises, we recommend you start off light before increasing the weight. Increase the speed of the movement as you become confident in both accelerating and decelerating. Exhale as you lift up and inhale as you approach the target ankle. Make sure no one is close by when you perform this exercise and try not to let go of the dumb-bell!