Here is a terrific exercise that not only strengthens your back and buttocks but also helps to align your spine and stretch your chest and hips.
Lie face-down on a mat with your legs straight behind you. Place the palms of your hands on the floor near your hips and outer thighs. Keep your inner legs close together with the soles of your feet facing upward. Slide your shoulder blades down your back and press your hands firmly on the floor.
On an inhalation, reach out through the crown of your head as you arch your upper back and raise your right leg off the floor. Pause at the peak of the lift and take two to three breaths while continuing to hold your head, shoulders, chest and leg off the floor. Make sure you don't bend your knees or roll to one side during the entire movement. Release and lower your upper body and leg to the floor. Repeat, but this time raise your left leg off the floor. Continue to alternate until you have done six to eight lifts with each leg.
Voight is the creator of a line of fitness DVDs, including "Full Body Stretch" and "Ballet BodySculpt."