Lie on your back with your arms extended straight over your head so your body forms a straight line. Bend your knees and keep your feet flat on the floor then – keeping your arms locked – contract ...

(a) Lie on the floor, knees bent, holding a medicine ball overhead. Keeping your arms straight and core tight, raise the ball over your knees. Lower back to start. That’s one rep. Do 10. (b) On the ...