Tui na involves stretching, kneading and pushing the muscles, while Zhi Ya involves pressing and pinching acupressure points to relieve stress and pain. Each technique is based on therapeutic principles with relative effects such as stimulating the body to release more hormones, regulating blood flow or boosting energy or recovery. "Shou fa" or hand techniques are further categorized into sedating techniques or "yin" and stimulating techniques or "yang." The idea is to balance both yin and yang to achieve full health.