Sat Bir Khalsa is a yoga researcher who spent his career at Harvard Medical School and Brigham and Women's Hospital, and now serves as Director of Yoga Research for the Kundalini Research Institute. He developed a logic model that maps how yoga's components (postures, breathing, meditation) act on shared physiological and psychological mechanisms to produce measurable health outcomes. His model is widely cited in yoga therapy research as a framework for studying yoga as a whole practice rather than isolated techniques.