a. Hanging knee raise
Sets: 3  Reps: 12

Hold a chin-up bar with an overhand grip. Bend at the hips and pull your legs up as far as you can, lifting your knees in to your chest. Slowly lower yourself with your feet together and steady yourself before starting another rep.

b. Medicine ball chop
Sets: 3  Reps: 12 (each side)

Stand with feet shoulder-width apart and hold a medicine ball in both hands over your left shoulder. Then slowly swing the ball down and cross your body to the outside of your right leg. Do 12 reps, then switch sides.