Your spine is naturally curvy. Near the top of your back, your thoracic spine rounds slightly, while the lower part of your spine, called the lumbar spine, creates the curve in the back known as the "arch." Exercises that cause the spine to extend, or bend backward, emphasize the arch in your back. These exercises strengthen the muscles that support your spine, especially those in your lower back, and they help lengthen the muscles along the front of your torso and pelvis.
This yoga pose warms up the spine, emphasizing both the thoracic curve and the lumbar curve.
To do the Cat-Cow, start on all fours with a neutral spine, your hands under your shoulders and your knees under your hips. Inhale and drop your belly down toward the floor, lifting your hips and head and opening across your chest. Inhale as you reverse the position, rounding your back and tucking your pelvis and chin. Alternate between the two positions for five to 10 rounds.
Another yoga position, this exercise lengthens the abdominal and hip flexors and strengthens the low back muscles, both of which are necessary to progress to more advanced back-bending exercises.
Baby Cobra: Lie on your stomach on the ground with your legs extended and your palms on the floor next your chest. Keeping your neck long, press through your hands to lift your chest off the ground. Use the strength of your lower back, rather than your arms, to lift your upper body. Keep your elbows pointing back behind you. Holding here, try to lift your palms off the ground for a few seconds at a time.
Go deeper: From the starting position, press up a little higher this time, still using your lower back strength, not your arms. Press up until your elbows are bent at about 90 degrees or more. Keep your hip points in contact with the ground.
Final step: This time, press until your arms are almost straight. Stop if your hip points start to lift off the ground.
Half-Bridge and Full-Bridge
This is the ultimate back-bending exercises in which your body looks like a true "arch" in the advanced version. Start with half-bridge if you're a beginner, and progress gradually; backbending can be dangerous if not done correctly and conservatively.
Half-Bridge: Lie on your back with your knees bent and your feet flat on the floor. Extend your arms alongside your body with your palms down. Keep your knees and feet hip-distance apart throughout the exercise. Press through your feet and lift your hips off the ground, until your pelvis comes in line with your knees.
Next step: From the starting position of half-bridge, place your hands on the floor next to your head with your fingers pointing back toward your shoulders. Push through your feet and hands to lift your body off the floor. Tilt your head back and rest the top of your head on the floor. Keep your elbows as close to parallel as possible.
Full-Bridge: Extend your arms and legs to lift your head off the floor. Straighten your elbows and knees, and press your chest forward, as if you're trying to touch it to the wall behind you. Press your hip points up toward the ceiling.
Whichever version you're doing, hold for as long as you can. Then come down and rest, and repeat one or two more times.