Maintaining Balance: Paripurna Navasana
To maintain healthy, balanced muscle tone on all sides of the spine, you will also need to strengthen the paraspinal muscles of the lower back, which support the inward arch of the lumbar spine, and to stretch the hip flexors, especially the psoas. It’s important to keep these muscles strong and supple, balancing their strength with the strength of the abdominals. If you overdo the abdominal exercises described here and don’t balance them with lower back strengtheners, you may end up creating too much of a backward tilt in your everyday posture, flattening your lumbar curve.
Toning the lower abdominals in your yoga practice will protect your lower back in your daily life as well.
Attaining this balance in your practice is quite simple. Ardha navasana (half boat pose) works the obliques directly while countering the pull of the hip flexors. Paripurna navasana (full boat pose) does the opposite: it strengthens the paraspinal muscles of the lower back as well as the hip flexors, particularly the quadriceps and psoas, while the abdominals work only moderately.
Paripurna navasana is often thought to be an abdominal pose, but only because it is so often done with the spine misaligned. If your lower back is weak, you will roll back toward your tailbone, your abdominals will grip to hold you up, and your thighs and hips may grip and cramp as well. But when you execute the pose correctly, your back is straight, or even slightly arched. Your lower back muscles work strongly, while the hip flexors can release some of their gripping action in the hips.
To start, sit with both knees bent and your feet on the floor (you can do this posture with or without a yoga wheel). Hold your thighs with your hands so that your fingertips are behind the knees. Lean back into the yoga wheel to straighten your spine, bringing a small arch into your lower back (the yoga wheel will help you with it).
Keep your head slightly forward. As you rock back on the back edges of your sit bones—but not so far that you come onto your tailbone—your feet will rise a few inches off the ground. Keep your spine straight and steady.
Lift your feet until your shins are parallel to the floor.
Pull with your hands against your thighs to keep your spine straight and your hip joints relatively relaxed. Use your hands to spiral your thighs inward so that they remain parallel, with the inner edges of your thighs firm: the support of these adductors will help your lower back.
If your lower back feels strong (i.e., you’re not rocking back onto your tailbone), your chest is lifted and open, and your shoulders are back, then press your thighs into your hands and start to straighten your legs using the strength of your quadriceps.
Don’t allow your knees to turn out; by spiraling your thighs inward, you will maintain the strength of your lower back.
To complete the pose, extend your arms forward, parallel to both each other and to the floor. Draw your shoulders straight back again to keep your chest open and lifted. Draw your chin back to work your neck muscles.
The main work should be in your lower back and thighs, with some toning throughout the abdominals. In the full pose, your hip flexors (at your hip creases) will be working as well, but if they begin to grip and cramp, it’s because your lower back and quadriceps are weakening and your pelvis is tipping back. In that case, hold your thighs with your hands to keep your lower back strong.
Abdominal exercises inevitably involve some tightening of the psoas, so if you fail to release the psoas after this work, you may end up with a stiff, sore lower back. Do a mild variation of eka pada rajakapotasana (king pigeon pose) to release the psoas and other hip flexors. Start with one knee bent and the sole of the foot near the opposite groin. Extend the entire length of the other leg behind you straight on the floor. Reach back through the toes of the back leg, gently pressing the top of your foot into the floor to activate the thigh. Now lift up through your lower belly to get a stretch and release deep inside the pelvis, where the psoas lies. Repeat the pose on the other side.
Using Your Abdominals in Twisting Poses
Abdominal support is especially important in twisting poses where it stabilizes the otherwise vulnerable lumbar spine. To come into a simple seated twist, initiate the twist from the external obliques on your left side. Simultaneously, activate the internal obliques on your right side. This will keep your lower belly firm and lifting. Keep a neutral arch in your lower back, not tipping your pelvis back; and keep the left sit bone grounded. As you maintain an inward arch of your lower back, turn your hips slightly in the direction opposite to the twist to keep your foundation stable.
With support from the obliques, the twist comes more from the middle and upper back, and less from the lumbar spine. The deepest part of the twist comes from a gentle lift just above the pelvic floor. As you’ll see, it is possible to turn from the pit of your abdomen from the action of your obliques, while keeping your hips and lower back stable, giving a gentle, healthy squeeze to your inner organs. Repeat this entire process on the other side.
This approach to twisting, which honors the protective role that the abdominals play for the lumbar spine, makes the pose safe, as well as energizing. Your lumbar disks will thank you for it.