High lunge, or crescent moon (also called Alanasana, although there’s not really an agreed-upon Sanskrit name for this pose) opens the hip flexors, strengthens the hip extensors, helps to develop a strong core and balance, and is excellent preparation for Virabhadrasana I (Warrior I).
Begin in Adho Mukha Svanasana (Downward-facing Dog). Raise your right leg above your torso into Three-legged Dog. As you exhale, step your right foot between your hands and align your knee above your ankle. Curl your left toes under and reach back through your left heel. Bring your hands to your right thigh and pause here, hug your thighbones in toward one another to create grounded support.
Inhale and lift your torso up. Rest your hands on your hips. Sink your right thigh toward the floor as you lift your inner back thigh and internally rotate it toward the sky. Continue to press through your left heel and extend your arms overhead.
Now, lift your chest, reach through your fingers, and draw your arms back toward your head, lifting up through your biceps. If your shoulders or low back feel tight, spread your arms more widely apart or keep your torso moving slightly forward of your hips.
Feel the connection between the crown of your head and your tailbone. Draw your abdominals in, lengthen your tail toward the earth and hug your front ribs in lightly toward the back body. From this core stability, draw energy up toward your heart. Draw your chin lightly in towards your throat, keeping a sense of containment – and contentment – within your heart space.
Excerpt from Article Alanasana: High Lunge/Crescent Moon By Chrisandra Fox Walker