To perform a proper Plank, you must:
- Get into a face down position on the floor supporting your upper body on your forearms.
- Your elbows should be bent at 90 degrees.
- Extend your legs straight out behind you, supporting them on your toes and balls of your feet.
- Keep your body in a straight line by tightening your abdominal and oblique muscles.
- Hold for as long as possible.