The plank is an isometric core strength exercise that involves maintaining a position similar to a push-up for the maximum possible time

1. Start in a push-up position with your arms straight and hands shoulder-width apart.
2. Lower your forearms to the ground, keeping your elbows directly beneath your shoulders.
3. Engage your core and maintain a straight line from your head to your heels.
4. Hold the position for the maximum possible time.