REVOLVING HALF-MOON POSE
Parivrtta ardha chandrasana merges balancing with twisting. As with Parivrtta Trikonasana and Parivrtta Parsvakonasana, the shoulder girdle and pelvis move in opposite directions, connected by the revolving spinal column. Initially we use the hand on the floor for stability; as balance in the pose improves, press the hand into the mat and use it to lever the body deeper into the twist. Work to align the femur over the tibia and ankle, so that the bone strength supports the weight of the body while perpendicular to the floor. Raise and lower the pelvis to work with the center of gravity and maintain balance. If you waver or start to fall, bend the standing-leg knee and/or lower the raised leg from the hip to regain stability. Extend the upper arm straight up into the air and use it to lever the upper-side chest into the twist. Create a line of action extending back through the raised-leg heel to constrain the body back, and then open the chest forward in the opposite direction. This creates an energetic coil from the heel to the top of the head. Pelvic stability is the key to success in this pose. Obtain this by engaging the psoas of the standing leg and the gluteus maximus of the raised leg. These two opposing actions create a helical force across the pelvis, tethering it in place and minimizing wavering in the pose.
BASIC JOINT POSITIONS
Bend the front knee and grasp the outside of the lower leg with the hand, as with Parivrtta Trikonasana. Bend the elbow to lever the torso into a twist against the thigh. Roll the upper shoulder back and raise the upper arm to turn the chest.
Next, walk the back foot toward the front, and at the same time, bring the lower-side hand a few inches ahead of the front foot. Pause for a moment in this position. Maintain the torso turning and squeezing against the front thigh; this engages the hip flexors, including the psoas. With the standing leg bent, tilt the torso down while contracting the gluteal muscles to raise the back leg like a teeter totter. Squeeze the buttocks muscles to lift the leg parallel to the floor. Simultaneously contracting these two muscles—the psoas and the gluteus maximus—stabilizes the pelvis. Finally, activate the quadriceps to straighten the knee and lift the torso like the action of a hydraulic lift.
STEP 1 Engage the hip flexors, including the psoas, pectineus, and adductors longus and brevis, to bend the torso over the standing leg. Bend from the pelvis rather than rounding the back to come into the pose. Engage the quadriceps to straighten the standing leg. Contracting this muscle group automatically activates the rectus femoris, a subpart of the quadriceps. The rectus femoris and sartorius cross the pelvis and knee and synergize the psoas to flex the trunk over the leg. These polyarticular muscles all cross multiple joints; this creates a connection that extends from the lumbar spine to the lower leg.
STEP 2 Lift the back leg by contracting the gluteus maximus, the prime mover of hip extension. This muscle also externally rotates the femur. In this pose, we want the kneecap to face directly down. To accomplish this we need to counteract the external rotation caused by the gluteus maximus contracting. Do this by activating the tensor fascia lata and gluteus medius to internally rotate the femur. A cue for this is to imagine pressing the outer edge of the back foot against a wall. This invokes both the abduction and internal rotation components of the tensor fascia lata and gluteus medius and illustrates “dual action” of a muscle. When you try this cue, don’t let your leg abduct to the side. Instead, engage the adductor magnus to resist this action. The adductor magnus also synergizes the gluteus maximus in extending the hip. Straighten the knee by engaging the quadriceps. The already contracted tensor fascia lata helps to straighten the knee. The peroneus longus and brevis on the side of the lower leg engage to evert and open the sole of the foot backwards.
STEP 3 The quadriceps and knee form the extensor mechanism of the standing leg. This combination functions like a hydraulic lift to straighten the knee and lift the pelvis in this pose. When we stand on one leg, the gluteus medius automatically contracts to tether the pelvis in place. The tensor fascia lata along the side of the leg synergizes both this action and that of straightening the knee. Align the femur over the tibia and ankle, so that the weight is supported by the arch of the foot. Activate the arch by contracting the peronei at the side of the lower leg to press the ball of the foot into the floor.
STEP 4 Contract the lateral deltoids to abduct the arms, and contract the triceps to straighten the elbows. Engage the pronators teres and quadratus to internally rotate the lower-side forearm and press the palm of the hand into the floor. Externally rotate the shoulders by activating the infraspinatus and teres minor muscles. The opposing rotations of the forearm and shoulder produce a double helical force through the arm. Activate the lower-side serratus anterior to press down from the shoulder into the floor. Contract the upper-side rhomboids to draw the scapulae toward the spine. Feel how this aids to turn the chest.
SUMMARY All of these steps culminate in a rotational pose that also trains balance. The focal point of the stretch is the back of the standing leg, including the gastrocnemius/soleus complex, the hamstrings, and the gluteus maximus. The upper-side oblique abdominals and the pectorals lengthen. The lower-side erector spinae and rhomboids stretch. The stretch is the result of flexing and rotating the trunk and straightening the knee. Engaging the muscles that create the form of the pose produces reciprocal inhibition of the muscles that stretch.
