Hold a dumb-bell in your left hand and balance on your right leg. Keeping your lower back in its natural arch, bend forward at the hips and knee until the dumb-bell is just below your knee.

Explosively extend your hips and knee and shrug the weight up. When the weight reaches your chest, flip your wrist over so that the momentum carries the weight straight over your head. Lower the weight back down. That’s one rep. Complete 10 reps, and then switch sides and repeat with the opposite arm.