The definitive core exercise. The plank involves minimal movement but maximal effort, requiring you to support your body on your forearms and toes while holding your body in a straight line from your shoulders to your ankles. You can make it easier by resting on your knees, or harder by extending your arms so you’re supported by your hands.
Lie on your back with your arms extended straight up towards the ceiling, and your legs raised with your knees bent at 90°. Lower your right arm and left leg at the same time until they are hovering just above the floor, then return to the starting position. Then do the same with the opposite limbs.
Sit on the floor with your knees bent. Lean back slightly, keeping your back straight, and hold your arms out in front of you as you raise your feet off the ground with your legs together. If you can, extend your legs so they are straight and your body forms a V shape. You can also raise your arms and spread your legs to make the hold harder.