The plank is a lot harder than it looks. It’s a core exercise designed to improve strength and tone in the stomach and lower back.
Get into a prone position on the floor bending your elbows at 90 degrees with your forearms on the floor and elbows directly beneath your shoulders. You will be supporting your weight on your toes and your forearms.
Your body should be straight like a plank of wood from your head to your feet. Beginners have a tendency to lifting their hips up in the air. This is not a plank and decreases the effectiveness of the exercise.
Keep your body straight, and hold this position as long as possible. Increase difficulty by raising an arm or leg.
For those who are struggling with the plank then a modified plank with your knees on the floor will make it a lot easier.