Virabhadrasana III (Warrior 3) is a fundamental standing balance that strengthens the body and steadies the mind.
The muscles of the foot, ankle, and calf work strongly in the standing leg to steady the balance. The quadriceps support the standing knee and the hamstrings engage eccentrically to regulate flexion of the hip. In the lifted leg, the glutes engage to extend the hip while the tensor fascia lata works against these muscles to prevent external rotation. In the torso, the spinal extensors, abdominals, and psoas engage to support and elongate the spine. The trapezius, deltoids, and triceps extend the shoulders and straighten the arms.
The foundation of balance in any of the single-legged postures is in the feet. Press into the big toe and lift through the arch of the foot to activate the muscles of the lower leg and contribute to the lightness of the pose. Microbend the standing knee to avoid hyper-extending at the joint and be aware of any external rotation in either leg caused by overuse of the glutes. There is a tendency, especially in the extended leg, to roll the hip open in order to recruit the gluteus maximus more fully. Use a slight internal rotation of the extended leg to drop the hip and counteract any imbalance in the pelvis.
Draw the shoulderblades onto the back to bring the tops of the shoulders away from the ears as you stretch out through the fingertips. Lift the spine, arms, and extended leg parallel to the floor beneath you. Consciously engage the muscles of the abdomen to prevent overuse of the spinal extensors. Point the sternum forward as you push back through the sole of the foot. Use the gaze to steady your mind. Imagine that you are drawing energy up from the earth through the standing leg and directing it out through both ends.
If you feel strain in the low back while practicing Virabhadrasana III, you may press the palms in anjali mudra at the heart center or bring the fingertips to the floor. A variety of arm positions may be used in this posture to change the focus or level of challenge. A couple of my favorite variations include fingers interlaced behind the back to help keep the chest lifting or with Garudasana (Eagle Pose) arms for a nice stretch across the shoulders and upper back.