**3. Hat.ha Yoga**

*Hat.ha Yoga*, the form of yoga most commonly practiced in yoga studios around the world and which has been the subject of most of the scientific studies that we will invoke below, involves a number of developments based on its conception of the body as a complicated system of pneumatic and hydraulic forces. Breath control becomes highly advanced in this form of yoga with increasingly involved practices that include precise degrees of control of the breath, sometimes leading to long periods of both extremely deep breathing and breath stoppage (White 2012, pp. 15–16). These practices are aimed at awakening and then propelling upwards the *kun. d. alin¯ı*, a serpentine force viewed as lying coiled, dormant at the base of the spine that represents the potential of *sakti ´* or energy in the body and which, when awakened, travels up through the *sus.umn. a¯* passage in the spine and pierces the energy *cakras* as it flies up to the top of the head, bursting into the cranium and delivering a state of ecstasy and bliss. According to Sarbacker: "This upward movement is homologized with an ascension through the cosmological process itself, from the gross elements to the subtle reality of consciousness, through the concentric circles on the vertical axis of the *sus.umn. a n¯ a¯d.¯ı*" (Sarbacker 2021, p. 163). Here, the human being is conceived of as a microcosm of the universe, with the soul equivalent to the divine power which is the ground of all being, the *na¯d.¯ıs* or channels equivalent to the great rivers that feed the world, the spine representing Mount Meru, the lofty center of the universe.

The Tantric tradition that established much of the foundation for Hat.ha Yoga did not deny the body entirely but perceived it to be a vessel where the divine resides, one that could be used to experience the divine through the creation of a transubstantiated body that is the result of these practices. In contrast to earlier forms of yoga whose aim was to entirely separate the soul from the body, Hat.ha Yoga accepts and uses the body in the quest for higher goals. The *Yoga-Sik ´ a-Upani ¯ s. ad* observes that The Absolute (*Brahmatva*) has attained embodiment (*Dehatva*), even as water becomes a bubble. The phases of matter are portrayed metaphorically by water changing from a liquid form to a bubble form, which requires heat or an abundance of light (Feuerstein 2013, p. 382). The key insight of this analysis is that, here, the body is used to achieve the goals rather than being completely denied or renounced, thus producing the kind of beneficial effects outlined in some of the studies we will present below. The concept of the subtle body *(suk¯ s.ma-´sar¯ıra*), an inner body that houses the main lifegiving functions and energies that support the gross material body, is a key player in this drama, for it is through purification and perfection of this subtle body that the beneficial effects are felt in the gross body. The "subtle body" as described as early at the 6th century BCE in the *Chandogya Upani ¯ s. ad* (Section 8.6) includes a series of channels (*na¯d.¯ı*) that bloom out of a central channel, known as the *sus.umn. a n¯ a¯d.¯ı* (Jha 1942, pp. 441–46). The *suk¯ s.ma-´sar¯ıra* is described as having wheels (*cakra*) or lotuses (*padma*) where the vital energy (*pra¯n. a*) and drops (*b¯ıja, bindu*) of vitality move throughout the *na¯d.¯ı*. The physiology underlying Hat.ha Yoga became fully developed in the medieval period and holds that the *suks ¯ .ma-´sar¯ıra* may have knots (*granthi*) that inhibit the flow of vital energy throughout the na¯d.¯ı. To alleviate *granthi* within the *suk¯ s.ma-´sar¯ıra, layayoga, kun. d. alin¯ıyoga,* and *hat.hayoga* began to be practiced in order to affect the free flow of vital force (Sarbacker 2021, p. 162).

The most popular forms of yoga practiced today are Hat.ha and Vinyasa, both of which ¯ take the traditional modalities discussed above and mix them with newer developments that were adopted from other sources, such as British calisthenics used in the Indian Army as well as the developing gymnastic and bodybuilding practices of the West (Singleton 2010). The sun salutation is an exemplification of the practice of Vinyasa, which builds ¯ on the Hat.ha Yoga practice of "victorious breath control" (*ujjay¯ ¯ı-pra¯n. ay¯ ama ¯* ). Vinyasa also ¯ includes other forms of breath control called the "upward flying" (*ud. d.¯ıyana ¯* ) abdominal and "root" (*mula ¯* ) pelvic lock. It is also referred to as *ud. d.¯ıyana ¯* "binding" (*bandha*), which means holding on to the breath after a full expiration. Vinyasa incorporates the use of a ¯ focused gaze (*dr.s.t.i*) on a point on the body or in space while practicing the more developed form of breath control and performing certain postures (*asana ¯* ) with movements of the body. Vinyasa moves from one pose to the next in a fluid manner, whereas Ha ¯ t.ha tends to hold one in the locked poses for longer. Bikram Yoga emphasizes the ranges involved in *asana ¯* such as static *asana ¯* (seated postures) and dynamic *asana ¯* (standing postures) but in an extremely hot environment (Sarbacker 2021, p. 196).

The traditional views of the body explain how the thinkers who laid out the yogic system thought it worked, but their claims and insights do not necessarily correspond to modern scientific understandings of the body. While some question how verifiably measurable the benefits of the practices that are grounded in the action of yoga's postures, breathing techniques, and mental habits are, when the results of specific practices are subject to repeated testing and experimental replication, results can be affirmed as having pragmatic value even if the mechanisms of such effects are poorly understood (Van Fraassen 1980, pp. 2–5). Indeed, there is a body of clinical research supporting these observations. Yoga practices have been shown to reduce stress levels and promote a healthy lifestyle, while boosting the immune and pulmonary systems, particularly the upper respiratory tract, the portal of entry for the SARS-CoV-2 virus infection (Bushell et al. 2020, p. 547). Additionally, the health of the respiratory system is an important line of defense in preventing fatality (Beltramo et al. 2021). Finally, yoga displays few adverse side effects (Bushell et al. 2020; Agarwal and Maroko-Afek 2018; Balkrishna et al. 2021). Clinical studies have suggested that yoga has immunity-inducing, pulmonary protective, stress-reducing, well-being improving, and overall ailment-alleviating results (Naoroibam et al. 2016, p. 57). This all suggests that overall health and well-being help combat COVID-19 and are fostered by yoga. With this background about the spiritual referents and health benefits now established, we may turn our attention to the SARS-CoV-2 viral outbreak, which the World Health Organization declared to be a widespread pandemic in March 2020.

We may recall that when the WHO made this declaration, independent national governments across the globe were urged to create emergency restrictions and regulations for mitigating the alarming spread of the SARS-CoV-2 virus and its virulent impact. The biggest obstacle to this effort was the uncertainty of the mode of transmission and morbidity of COVID-19. As the pandemic progressed in 2020, differential transmission trends in various contexts became visible. Prevalence rates of transmission and the morbidity and mortality statistics varied substantially across regions, races, ages, and communities of different socioeconomic status. Social determinants of health became a focal concern as strategies in preventing transmission grew in importance. In response to this crisis and uncertainty, one form of preventive care to which many turned was yoga, specifically Hat.ha or Vinyasa Yoga, along with their associated forms of meditation. To this end, we ¯ now consider what we have long known and have recently acquired evidence for with regard to yoga's efficacy in minimizing the severity of mental health struggles, boosting immunity function, and combating pulmonary ailments of the virus responsible for COVID-19. (Tillu et al. 2020, p. 2).
