This variation of High Lunge, sometimes called Crescent Pose, is a great preparation for the full version of Virabhadrasana I (Warrior I Pose).
Start in Downward-Facing Dog. Exhale and step your right foot forward between your hands, aligning your knee over the heel. Keep your left leg strong and firm.
Inhale and raise your torso to upright. At the same time, sweep your arms wide to the sides and raise them overhead, palms facing.
Be careful not to overarch the lower back. Lengthen your tailbone toward the floor and reach back through your left heel. This will bring the shoulder blades deeper into the back and help support your chest. Look up toward your thumbs.
Be sure not to press the front ribs forward. Draw them down and into the torso. Lift the arms from the lower back ribs, reaching through your little fingers. Hold for 30 seconds to a minute.
Then exhale, release the torso to the right thigh, sweep your hands back onto the floor, and, with another exhale, step your right foot back and return to Down Dog. Hold for a few breaths and repeat with the left foot forward for the same length of time.