Modified plank

Another good core-strength exercise is called the modified plank. In a plank, you raise yourself up on your forearms and feet while keeping your body lined up with your hips. To do a modified plank:

• Lie on your stomach. Raise yourself up so that you're resting on your forearms and knees. Line up your head and neck with your back. Place your shoulders directly above your elbows. Tighten the abdominal muscles.
• Create resistance by pressing your elbows and knees toward one another. Neither should move from their positions on the floor. Hold for three deep breaths.
• Return to the start position and repeat.