In Yin Yoga, poses are held for several minutes at a time in order to the stretch the connective tissue around the joints. The most prominent advocate of this method is the American teacher Paul Grilley, who learned the basic technique from Taoist Yoga teacher and martial arts expert Paulie Zink. Grilley also studied with the Japanese Dr. Motoyama, whose research posits that our connective tissue may actually be the key to discovering subtle energy channels in the body (called nadis in yoga and meridians in Traditional Chinese Medicine).
Despite having an advanced asana practice, which is supposed to help prepare the body for meditation, Grilley found himself uncomfortable when he began to attempt long, seated meditations.
Yin Yoga directly addresses the demands that sitting still in one position for a long time places on the body by focusing on stretching connective tissue instead of muscle. Sarah Powers, who studied with Paul Grilley, is another well-known teacher in this field.
Yin and Yang
In Chinese philosophy, the yin yang symbolizes the duality and interdependency of the natural world. Things that are yang are moving, changing, and vigorous. In contrast, things that are yin are still, static, and calm.
The majority of western yoga practices have evolved into being very yang- lots of movement, with an emphasis on stretching the muscles. Muscles are yang, while connective tissues like tendons and ligaments are yin. Sitting for meditation is more yin, and therefore requires a practice that adresses this use of the body. While joints like the knees and ankles are fragile and easily over stretched, the body also contains joints in the pelvis, hips and lower spine that are naturally much less flexible. It is these joints that yin yoga primarily addresses.