Reps: 20-50

Lie with your legs straight out and your fingers touching your temples.

Reps: 20-50

Raise and twist your torso to the left as you bring your left knee in to meet your right wrist.

Reps: 20-50

Lower your leg and torso without pausing and repeat on the other side so that your right knee meets your left wrist.

Reps: 15-30

Fix some weight plates to a barbell. Kneel down and hold the bar with an overhand, shoulder-width grip. Your shoulders should be above the bar and your hips over your knees.

Reps: 15-30

Slowly roll the bar forwards as far as you can. Keep your abs held tight and your torso in a straight line from shoulders to hips. Use your abs to pull you back again.

Reps: hold for 30 seconds to two minutes

Place your toes on a bench and your forearms on a stability ball so that your body forms a straight line from shoulders to ankles. Contract your abs and hold for 30 seconds to two minutes.