Begin by lying on your right side, legs extended and stacked, elbow directly underneath the shoulder, and forearm/elbow placed on top of a balance board (not pictured). Make sure your body is in a nice straight line from your feet to your head. With legs stacked, use your abs and obliques to lift your right hip away from the floor into a side plank position (pictured).
Breathe steadily as you hold the side plank position for 15-30 seconds, keeping your abs engaged and the right side of your waist pulled away from the floor at all times. For added intensity, extend your left arm up toward the ceiling (pictured). Gradually work your way up to holding the plank for 1-3 minutes for an isometric core challenge. Repeat on opposite side.
Hold your body as still as possible and try to keep the balance board steady, too. Remember to breathe. Try to square your chest and shoulders with the front of the room, keeping your body in one plane and your shoulders pulled back.
Make it easier: Instead of stacking your legs and feet, stagger one leg in front of the other; place left hand on the hip instead of extending it (not pictured).
Muscles Worked: Abs, Obliques