As conceptualized in the Taoist and Dharmic traditions, the sequences of postures are meant to stimulate the channels of the subtle body, known as meridians in Chinese medicine and as nadis in Hatha yoga.Yin Yoga poses apply moderate stress to the connective tissues of the body—the tendons, fasciae, and ligaments—with the aim of increasing circulation in the joints and improving flexibility.Zink's approach includes the full range of Taoist yoga, focusing on animalistic movements and the balancing of Yin and Yang energies.[4] Taoist priests taught long-held poses, along with breathing techniques, to Kung Fu practitioners beginning 2000 years ago, to help them fully develop their martial arts skills.[5] The practice of a series of long-held floor poses was introduced in North America in the late 1970s by the martial arts champion Paulie Zink.[12][13][14][15] In his first years of teaching, many of Zink's students were martial arts practitioners who had developed strong but tight muscles, and he taught them only beginner level Taoist Yoga, focusing on long-held yin poses to alleviate their lack of flexibility.[19] In 1989, Grilley met Hiroshi Motoyama, a Japanese scholar and yoga practitioner,[16] who had researched the physiology of Traditional Chinese Medicine and written on it extensively.[30] In the body, the relatively stiff connective tissues (tendons, ligaments, fascia) are considered yin, while the more mobile and pliable muscles and blood are called yang.[16] During the long hold times of the yin asanas, teachers usually give "dharma talks", informal monologues that often explain the physiology and anatomy of poses, including the meridian lines being affected.