Health science is the branch of science focused on health. There are two main approaches to health science: the study and research of the body and health-related issues to understand how humans (and animals) function, and the application of that knowledge to improve health and to prevent and cure diseases and other physical and mental impairments. The science builds on many sub-fields, including biology, biochemistry, physics, epidemiology, pharmacology, medical sociology. Applied health sciences endeavor to better understand and improve human health through applications in areas such as health education, biomedical engineering, biotechnology and public health.
The high levels of muscle growth and repair achieved by bodybuilders require a specialized diet. Generally speaking, bodybuilders require more calories than the average person of the same weight to provide the protein and energy requirements needed to support their training and increase muscle mass. In preparation of a contest, a sub-maintenance level of food energy is combined with cardiovascular exercise to lose body fat. Proteins, carbohydrates and fats are the three major macronutrients that the human body needs in order to build muscle.[24] The ratios of calories from carbohydrates, proteins, and fats vary depending on the goals of the bodybuilder.[25]

According to Geoffrey Samuel, our "best evidence to date" suggests that yogic practices "developed in the same ascetic circles as the early śramaṇa movements (Buddhists, Jainas and Ajivikas), probably in around the sixth and fifth centuries BCE." This occurred during what is called the ‘Second Urbanisation’ period.[8] According to Mallinson and Singleton, these traditions were the first to use psychophysical techniques, mainly known as dhyana and tapas. but later described as yoga, to strive for the goal of liberation (moksha, nirvana) from samsara (the round of rebirth).[78]
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.[46][47][unreliable medical source?][48]
Tantra is a range of esoteric traditions that began to arise in India no later than the 5th century CE.[181][note 17] George Samuel states, "Tantra" is a contested term, but may be considered as a school whose practices appeared in mostly complete form in Buddhist and Hindu texts by about 10th century CE.[183] Tantric yoga developed complex visualizations which included meditation on the body as a microcosm of the cosmos. They included also the use of mantras, pranayama, and the manipulation of the subtle body, including its nadis and cakras. These teachings on cakras and Kundalini would become central to later forms of Indian Yoga.[184]
Organized interventions to improve health based on the principles and procedures developed through the health sciences are provided by practitioners trained in medicine, nursing, nutrition, pharmacy, social work, psychology, occupational therapy, physical therapy and other health care professions. Clinical practitioners focus mainly on the health of individuals, while public health practitioners consider the overall health of communities and populations. Workplace wellness programs are increasingly adopted by companies for their value in improving the health and well-being of their employees, as are school health services in order to improve the health and well-being of children.

Classical yoga incorporates epistemology, metaphysics, ethical practices, systematic exercises and self-development techniques for body, mind and spirit.[144] Its epistemology (pramana) and metaphysics is similar to that of the Sāṅkhya school. The metaphysics of Classical Yoga, like Sāṅkhya, is mainly dualistic, positing that there are two distinct realities. These are prakriti (nature), which is the eternal and active unconscious source of the material world and is composed of three gunas, and the puruṣas (persons), the plural consciousnesses which are the intelligent principles of the world, and are multiple, inactive and eternal witnesses. Each person has a individual puruṣa, which is their true self, the witness and the enjoyer, and that which is liberated. This metaphysical system holds that puruṣas undergo cycles of reincarnation through its interaction and identification with prakirti. Liberation, the goal of this system, results from the isolation (kaivalya) of puruṣa from prakirti, and is achieved through a meditation which detaches oneself from the different forms (tattvas) of prakirti.[243] This is done by stilling one's thought waves (citta vritti) and resting in pure awareness of puruṣa.

Ascetic practices, concentration and bodily postures described in the Vedas may have been precursors to yoga.[59][60] According to Geoffrey Samuel, "Our best evidence to date suggests that [yogic] practices developed in the same ascetic circles as the early sramana movements (Buddhists, Jainas and Ajivikas), probably in around the sixth and fifth centuries BCE."[8]
Vajrayana is also known as Tantric Buddhism and Tantrayāna. Its texts were compiled starting with 7th century and Tibetan translations were completed in 8th century CE. These tantra yoga texts were the main source of Buddhist knowledge that was imported into Tibet.[187] They were later translated into Chinese and other Asian languages, helping spread ideas of Tantric Buddhism. The Buddhist text Hevajra Tantra and Caryāgiti introduced hierarchies of chakras.[188] Yoga is a significant practice in Tantric Buddhism.[189][190][191]
Various yogic groups had become prominent in Punjab in the 15th and 16th century, when Sikhism was in its nascent stage. Compositions of Guru Nanak, the founder of Sikhism, describe many dialogues he had with Jogis, a Hindu community which practiced yoga. Guru Nanak rejected the austerities, rites and rituals connected with Hatha Yoga. He propounded the path of Sahaja yoga or Nama yoga (meditation on the name) instead.[204] The Guru Granth Sahib states:
Malaysia's top Islamic body in 2008 passed a fatwa, prohibiting Muslims from practicing yoga, saying it had elements of Hinduism and that its practice was blasphemy, therefore haraam.[298] Some Muslims in Malaysia who had been practicing yoga for years, criticized the decision as "insulting."[299] Sisters in Islam, a women's rights group in Malaysia, also expressed disappointment and said yoga was just a form of exercise.[300] This fatwa is legally enforceable.[301] However, Malaysia's prime minister clarified that yoga as physical exercise is permissible, but the chanting of religious mantras is prohibited.[302]
Many trainees like to cycle between the two methods in order to prevent the body from adapting (maintaining a progressive overload), possibly emphasizing whichever method more suits their goals; typically, a bodybuilder will aim at sarcoplasmic hypertrophy most of the time but may change to a myofibrillar hypertrophy kind of training temporarily in order to move past a plateau. However, no real evidence has been provided to show that trainees ever reach this plateau, and rather was more of a hype created from "muscular confusion".[clarification needed][citation needed]
Health, as defined by the World Health Organization (WHO), is "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity."[1][2] This definition has been subject to controversy, as it may have limited value for implementation.[3][4][5] Health may be defined as the ability to adapt and manage physical, mental and social challenges throughout life.[6]