The plank is a handstand and balance pose that strengthens the abdominal and lower-back muscles as well as the shoulders and upper back. Variations of the plank provide different levels of challenge and work diverse muscle groups. For example, the high and low planks engage the rectus abdominus and lower-back muscles, while the side plank focuses more on the obliques. The reverse plank focuses more on the lower back.
Brace your abs and raise your hips into the air as described above, but keep your knees straight. From there, bend your knees and roll the ball back toward you. Keep your hips elevated throughout the set.
Place the ball against a wall and stand with your back against it, holding it in place. Place your feet shoulder-width, and turn your toes out about 15°. Squat down as low as you can, rolling the ball down the wall as you descend.
Lie back on a Swiss ball so your upper back is supported, and your butt is in front of the ball hovering above the floor. Place the soles of your feet together, and rest them on the floor in front of you. Brace your abs, push your knees out, and drive your feet into the floor to raise your hips until they’re level with your torso.
Lie face-up and rest your feet on the ball. Bend your knees 90°, rolling the ball toward you a bit. Brace your abs, and drive through your heels to raise your hips into the air until they’re in line with your torso.