Yoga as exercise The postural yoga of the Western world is a physical activity consisting of asanas (often connected by smooth transitions, sometimes accompanied by breathing exercises and usually ending with a period of relaxation or meditation. It is often known simply as "yoga", despite older Hindu traditions (some dating to the Yoga Sutras) in which asanas played little or no part; asanas were not central to any tradition. Yoga as exercise is part of a modern yoga renaissance, a 20th-century blend of Western gymnastics and haṭha yoga pioneered by Shri Yogendra and Swami Kuvalayananda. Before 1900, hatha yoga had few standing poses; the Sun Salutation was pioneered by Bhawanrao Shrinivasrao Pant Pratinidhi, the Rajah of Aundh, during the 1920s. Many standing poses used in gymnastics were incorporated into yoga by Krishnamacharya in Mysore between the 1930s and the 1950s. Several of his students founded schools of yoga. Pattabhi Jois created ashtanga vinyasa yoga, which led to Power Yoga; B. K. S. Iyengar created Iyengar Yoga and systematised asanas in his 1966 book, Light on Yoga; Indra Devi taught yoga to Hollywood actors; and Krishnamacharya's son, T. K. V. Desikachar, founded the Krishnamacharya Yoga Mandalam in Chennai. Other schools founded during the 20th century include Bikram Choudhury's Bikram Yoga and Swami Sivananda of Rishikesh's Sivananda yoga. Modern yoga has spread around the world. The number of asanas used in yoga has increased from 84 in 1830 (as illustrated in Joga Pradipika) to about 200 in Light on Yoga and over 900 performed by Dharma Mittra by 1984. The goal of haṭha yoga (spiritual liberation through energy) was largely replaced by the goals of fitness and relaxation, and many of its more esoteric components were reduced or removed. The term "hatha yoga" also refers to gentle yoga, often for women. Yoga has developed into a worldwide, multi-billion-dollar business involving classes, teacher certification, clothing, books, videos, equipment, and holidays. The ancient, cross-legged lotus position and Siddhasana are widely-recognised symbols of yoga. The United Nations General Assembly established 21 June as the International Day of Yoga, and it has been celebrated annually around the world since 2015. On 1 December 2016, yoga was listed by UNESCO as an intangible cultural heritage. The effect of postural yoga on physical and mental health has been a subject of study, with evidence that regular yoga practice is beneficial for low back pain and stress. In 2017,