According to Pāṇini, the term yoga can be derived from either of two roots, yujir yoga (to yoke) or yuj samādhau ("to concentrate"). In the context of the Yoga Sutras of Patanjali, the root yuj samādhau (to concentrate) is considered by traditional commentators as the correct etymology. In accordance with Pāṇini, Vyasa who wrote the first commentary on the Yoga Sutras, states that yoga means samādhi (concentration).
Alexander the Great reached India in the 4th century BCE. Along with his army, he took Greek academics with him who later wrote memoirs about geography, people and customs they saw. One of Alexander's companion was Onesicritus, quoted in Book 15, Sections 63–65 by Strabo, who describes yogins of India. Onesicritus claims those Indian yogins (Mandanis ) practiced aloofness and "different postures – standing or sitting or lying naked – and motionless".
"...[T]here is the cultivation of meditative and contemplative techniques aimed at producing what might, for the lack of a suitable technical term in English, be referred to as 'altered states of consciousness'. In the technical vocabulary of Indian religious texts such states come to be termed 'meditations' ([Skt.:] dhyāna / [Pali:] jhāna) or 'concentrations' (samādhi); the attainment of such states of consciousness was generally regarded as bringing the practitioner to deeper knowledge and experience of the nature of the world." (Gethin, 1998, p. 10.)
Overtraining occurs when a bodybuilder has trained to the point where his workload exceeds his recovery capacity. There are many reasons why overtraining occurs, including lack of adequate nutrition, lack of recovery time between workouts, insufficient sleep, and training at a high intensity for too long (a lack of splitting apart workouts). Training at a high intensity too frequently also stimulates the central nervous system (CNS) and can result in a hyperadrenergic state that interferes with sleep patterns. To avoid overtraining, intense frequent training must be met with at least an equal amount of purposeful recovery. Timely provision of carbohydrates, proteins, and various micronutrients such as vitamins, minerals, phytochemicals, even nutritional supplements are acutely critical. A mental disorder, informally called “bigorexia” (by analogy with anorexia), may account for overtraining in some individuals. Sufferers feel as if they are never big enough or muscular enough, which forces them to overtrain in order to try and reach their goal physique.
Yogaśataka a Jain work by Haribhadra Suri 6th century CE "With conviction, the lords of Yogins have in our doctrine defined yoga as the concurrence (sambandhah) of the three [correct knowledge (sajjñana), correct doctrine (saddarsana) and correct conduct (saccaritra)] beginning with correct knowledge, since [thereby arises] conjunction with liberation....In common usage this [term] yoga also [denotes the soul’s] contact with the causes of these [three], due to the common usage of the cause for the effect. (2, 4).
Tantra is a range of esoteric traditions that began to arise in India no later than the 5th century CE.[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. 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.