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The earliest references to hatha yoga are in Buddhist works dating from the eighth century. The earliest definition of hatha yoga is found in the 11th century Buddhist text Vimalaprabha, which defines it in relation to the center channel, bindu etc. Hatha yoga synthesizes elements of Patanjali's Yoga Sutras with posture and breathing exercises. It marks the development of asanas (plural) into the full body 'postures' now in popular usage and, along with its many modern variations, is the style that many people associate with the word yoga today.
Carbohydrates play an important role for bodybuilders. They give the body energy to deal with the rigors of training and recovery. Carbohydrates also promote secretion of insulin, a hormone enabling cells to get the glucose they need. Insulin also carries amino acids into cells and promotes protein synthesis. Insulin has steroid-like effects in terms of muscle gains. It is impossible to promote protein synthesis without the existence of insulin, which means that without ingesting carbohydrates or protein—which also induces the release of insulin—it is impossible to add muscle mass. Bodybuilders seek out low-glycemic polysaccharides and other slowly digesting carbohydrates, which release energy in a more stable fashion than high-glycemic sugars and starches. This is important as high-glycemic carbohydrates cause a sharp insulin response, which places the body in a state where it is likely to store additional food energy as fat. However, bodybuilders frequently do ingest some quickly digesting sugars (often in form of pure dextrose or maltodextrin) just before, during, and/or just after a workout. This may help to replenish glycogen stored within the muscle, and to stimulate muscle protein synthesis.
Muscle growth is more difficult to achieve in older adults than younger adults because of biological aging, which leads to many metabolic changes detrimental to muscle growth; for instance, by diminishing growth hormone and testosterone levels. Some recent clinical studies have shown that low-dose HGH treatment for adults with HGH deficiency changes the body composition by increasing muscle mass, decreasing fat mass, increasing bone density and muscle strength, improves cardiovascular parameters, and affects the quality of life without significant side effects.[unreliable medical source?]
The number of asanas used in modern yoga has increased rapidly from a nominal 84 in 1830, as illustrated in Joga Pradipika, to some 200 in Light on Yoga and over 900 performed by Dharma Mittra by 1984. At the same time, the goals of Haṭha yoga, namely spiritual liberation (moksha) through the raising of kundalini energy, were largely replaced by the goals of fitness and relaxation, while many of Haṭha yoga's components like the shatkarmas (purifications), mudras (seals or gestures including the bandhas, locks to restrain the prana or vital principle), and pranayama were much reduced or removed entirely. The term "hatha yoga" is also in use with a different meaning, a gentle unbranded yoga practice, independent of the major schools, sometimes mainly for women.