This challenging workout takes about 10 to 15 minutes. Your body weight provides resistance so you do not need any equipment. Keep your abdomen pulled in and your lower back rounded, pressed against the floor when possible. Hold the static positions for 30 seconds. For the movements, do either 30 repetitions or as many as you can in 30 seconds. Try to keep a smooth pace and do not rest for more than 30 seconds between exercises.
Lie flat on your back with your legs extended and arms by your sides. Press your lower back into the floor as you round your shoulder blades off the floor and raise your legs off the floor 2 to 3 inches. This is the basic hollow position. Hold it for 30 seconds. After a brief rest, hold the hollow position again, but extend your arms straight over your head. Do not let your lower back arch off of the floor.
From the hollow position with your arms at your sides, simultaneously sit up and bring your knees in toward your chest to balance for a split second on your rear, then lower back to an extended hollow, and repeat. These are lemon squeezers-imagine you are juicing a lemon that is balanced on your navel.
Rear raise: Lie flat on your back with your arms at your sides, legs straight, toes pointing straight up to the ceiling. Raise your rear end a few inches as you keep your toes pointing to the same spot. Lower gently and repeat.
Scissors: From the hollow position, scissor your legs in and out. Do not let your lower back arch off of the floor.
Backwards crunches: Lie on your back with your knees bent in to your chest, then raise your rear until it goes over your head, like the start of a backward roll. Lower to the starting position and repeat.
Side crunches: Lie on one side with your knees slightly bent and your body in a straight line from your shoulder to hip to heels. Lace your fingers behind your head to support your neck. Keep your legs on the floor as you crunch your upper body up as if trying to touch your elbow to your knee. Return to the starting position and repeat; then turn over onto your other side and repeat.
Middle crunches: Lie on your back as if to do a standard crunch, but point your toes up to the ceiling. Crunch from that position.
Elbow plank: With your belly facing the floor, support yourself only on your elbows and toes. Keep your rear as flat as possible and hold.
Side planks: With your right side facing the floor, support yourself only on your wrist (or elbow) and your right foot. Stack your left foot on top of your right. Keep your body in a straight line from your shoulder to your toes, and press your hips up as high as you can. Hold, then repeat on your left side.
Full plank: Use your wrists to support your belly-down plank. This is similar to the start of a push-up except you should extend your wrists in front of your shoulders as much as possible and hold the position.
Lie on your back with your arms overhead and your legs straight. Simultaneously lift your chest and legs to balance for a split second on your rear in a "V" position. Lower down gently and repeat. Keep your legs straight and together throughout the exercise.