Figures
Abstract
While yoga is gaining increased popularity in North America and Europe, its safety has been questioned in the lay press. The aim of this systematic review was to assess published case reports and case series on adverse events associated with yoga. Medline/Pubmed, Scopus, CAMBase, IndMed and the Cases Database were screened through February 2013; and 35 case reports and 2 case series reporting a total of 76 cases were included. Ten cases had medical preconditions, mainly glaucoma and osteopenia. Pranayama, hatha yoga, and Bikram yoga were the most common yoga practices; headstand, shoulder stand, lotus position, and forceful breathing were the most common yoga postures and breathing techniques cited. Twenty-seven adverse events (35.5%) affected the musculoskeletal system; 14 (18.4%) the nervous system; and 9 (11.8%) the eyes. Fifteen cases (19.7%) reached full recovery; 9 cases (11.3%) partial recovery; 1 case (1.3%) no recovery; and 1 case (1.3%) died. As any other physical or mental practice, yoga should be practiced carefully under the guidance of a qualified instructor. Beginners should avoid extreme practices such as headstand, lotus position and forceful breathing. Individuals with medical preconditions should work with their physician and yoga teacher to appropriately adapt postures; patients with glaucoma should avoid inversions and patients with compromised bone should avoid forceful yoga practices.
Citation: Cramer H, Krucoff C, Dobos G (2013) Adverse Events Associated with Yoga: A Systematic Review of Published Case Reports and Case Series. PLoS ONE 8(10): e75515. https://doi.org/10.1371/journal.pone.0075515
Editor: Ted S. Acott, Casey Eye Institute, United States of America
Received: May 17, 2013; Accepted: August 14, 2013; Published: October 16, 2013
Copyright: © 2013 Cramer et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: The authors have no support or funding to report.
Competing interests: The authors have declared that no competing interests exist.
Introduction
Yoga is rooted in Indian philosophy and has been a part of traditional Indian spiritual practice for around 3000 years [1]. While the goal of yoga has been described as uniting mind, body, and spirit, it has now become a popular means to promote physical and mental well-being [1], [2]. While yoga traditionally also comprises advice for ethical lifestyle and spiritual practice [1]–[4], it is most often associated with physical postures (asanas), breathing techniques (pranayama), and meditation (dyana) in North America and Europe [2]. These more physically-oriented yoga forms are gaining increased popularity as a therapeutic practice: in 2008, about 15% of the American adult population reported practicing yoga or being at least strongly interested in it [5]. Of those who were already practicing yoga, about half started practicing explicitly to improve their health status, resulting in more than 13 million people practicing yoga for health reasons [6], [7]. It has been estimated that about 30 million people are regularly practicing yoga worldwide [8]. Yoga has also been recognized as medical therapy: about 14 million Americans (6.1% of the population) reported that yoga was recommended to them by a physician or other therapist [5].
While yoga has often been regarded as beneficial and without harm, this view has been challenged in recent years. Mainly based on anecdotal evidence, the safety of yoga has been questioned in a number of lay-press articles [9]–[11]. In particular, a recent New York Times article by William J. Broad has listed a number of alarming cases of yoga-associated injuries [11]. As these publications seem to have led to a general uncertainty among yoga practitioners and those interested in starting practice [12], it is important to systematically assess the safety of yoga. Therefore, this review aims to assess published case reports and case series on yoga-associated adverse events in order to analyze a) which adverse events were most often reported, b) which yoga forms and specific practices were most often associated with adverse events, and c) which persons (e.g. those which specific preconditions) were most often reported to be affected.
Materials and Methods
Eligibility Criteria
Original English or German language case reports and case series were eligible if they were published in a peer-reviewed journal and reported on yoga-associated adverse events in healthy humans or human patients. Non-case reports such as clinical trials, reviews, basic research, or commentaries were excluded. A specific practice was regarded as ‘yoga’ if a) it was explicitly labeled as yoga by the authors, b) it was labeled with the name of a specific yoga practice, and/or c) the described practice clearly resembled typical yoga practices. Adverse events were classified as yoga-associated if they appeared in temporal connection with yoga practice and/or a causal relationship was assumed by the authors of the report.
Search Methods
An exploratory search in Pubmed was conducted on February 10, 2013 using the following search strategy: (Yoga[MeSH Terms] OR Yoga[Title/Abstract] OR Yogic[Title/Abstract] OR Asana[Title/Abstract] OR Pranayama[Title/Abstract]) AND (Case Reports[Publication Type] OR Case[Title/Abstract] OR Cases[Title/Abstract] OR Adverse[Title/Abstract]). Abstracts identified during this initial literature search were screened and adverse events that were associated with yoga practice in the retrieved abstracts were included in the final search strategy. In this search the following electronic databases were searched from their inception through February 15, 2013: Medline/Pubmed, Scopus, CAMBase, IndMed, and the Cases Database. The complete search strategy for each database is shown in table 1. Reference lists of identified original articles or reviews were searched manually. Additionally, the tables of contents of the International Journal of Yoga Therapy and the Journal of Yoga & Physical Therapy were reviewed.
Data Extraction and Management
For case reports, data were extracted on time of publication, country of origin, age and gender of the case, the specific yoga practice and yoga posture or breathing techniques, and the experience of the practitioner. Data on the reported adverse event, its treatment and clinical outcome were also extracted. For case series, the time of publication, origin, number of cases, the cases age and gender, the specific yoga practice and yoga posture or breathing techniques, the reported adverse event, its treatment and clinical outcome were collected.
Results
Literature Search
The literature search revealed a total of 517 non-duplicate records of which 469 were excluded because they did not report on yoga practices, were not case reports or case series or did not report adverse events. Out of 48 full-texts assessed for eligibility, 11 articles were excluded because they were not on yoga [13]–[20], were not case reports or case series [21]–[23], or were double publications on the same case [24]. Finally, 35 case reports [25]–[59] and 2 case series reporting on a total of 76 unique cases were included [60], [61] (Figure 1).
Reported Cases
Characteristics of the included case reports and case series are shown in table 2 and table 3, respectively.
Of the included 37 reports, 19 originated from the USA [28], [31]–[33], [35], [38]–[40], [43]–[47], [49], [52], [55]–[57], [61], 1 from Canada [60], 2 from the UK [51], [59], 1 from Germany [42], 1 from Switzerland [25], 2 from Italy [26], [34], 1 from Denmark [36], 5 from India [29], [41], [48], [53], [54], and 1 each from Nepal [27], China [37], Taiwan [58], South Korea [30], and Australia [50]. The first included report was published in 1969, the number of reports published each year gradually increased until 2012 (Figure 2).
Of the 76 cases, 66 had no preconditions that were associated with the adverse events while 9 case reports described an aggravation of existing preconditions, i.e. 3 cases of glaucoma [25], [35], [38], 3 cases of osteopenia [61], and 1 case each of asthma [55], psychosis [45], and affective disorder [59]. One case had a congenital hyperelasticity of connective tissue which might have facilitated the occurence of adverse events [34]. Fifty-one cases were female, 25 male; the mean age was 44.23 years.
The yoga practice that was most often associated with reported adverse events was Pranayama or yoga breathing with 4 reported cases [40], [41], [54], [55], followed by Hatha yoga (an umbrella term for physical yoga practices) [25], [31], [48] and Bikram yoga [43], [45], [51] with 3 cases each. Siddha yoga meditation [47], [56] and Vinyasa yoga (a yoga practice that involves flowing sequences of yoga postures synchronized to the breath) [28] were practiced in 2 and 1 cases, respectively. The other case reports or case series did not report the specific yoga practice.
Regarding specific yoga postures, the headstand (Sirsasana) was practiced in 10 cases [25], [27], [28], [32], [35], [37], [38], [46], [52], [53], the shoulder stand in 3 cases [36], [39], [52], variations of the lotus position (Padmasana) in 3 cases [26], [47], [56], forceful breathing techniques in 3 cases [40], [41], [55], voluntary vomiting (Kunjal Kriya) in 2 cases [27], [48], and postures that included putting 1 or 2 feet behind the head in 2 cases [34], [50]. Kneeling posture (Vajrasana) [31], locust pose (Salabhasana) [36], bridge pose (Setu bandha) [49], seated forward bend (Paschimottasana) [57], and downward-facing dog (Adho mukha savasana) [58] were practiced in 1 case each. One case of a female teenager was reported to have practiced “voluntary mouth-to-mouth Yoga breathing exercises with a teenage boy” [33]. Another case was reported doing “extreme yoga postures” that were not further characterized [29]. In 10 cases, the yoga practice that was associated with the adverse event was practiced under supervision [26], [42], [43], [45], [51], [54], [56], [58], [59], [61], in 4 cases it was unsupervised [33], [53], [55], [61]. The remaining reports did not state whether the practice was supervised or not.
In 27 cases, adverse events affected the musculoskeletal system and included fractures [26], [60], [61], ligament tears [50], [58], [60], joint injuries [60], fibrocartilaginous injuries [60], lumbar disc annular tears [60], myositis ossificans [44], and increased muscle enzymes [55]. Nine cases reported orbital adverse events including acute glaucoma [36], [52], worsening of chronic glaucoma [25], [35], [38], and orbital varices or vein occlusion [32], [46], [49], [53]. Peripheral neuropathy was reported by 4 cases [34], [47], [56], [57], stroke by 3 cases [37], [39], [49], and transient headache by 7 cases [60]. Three cases presented with pneumothorax [40], [41] or pneumomediastinum [33]. Two cases presented with rectum sheath hematoma [30], [54]. Ten further adverse events were reported just once [27]–[29], [42], [43], [45], [48], [51], [59], [60] (see tables 2, 3); the remaining 11 adverse events were unclear [60].
Fifteen cases reached full recovery without [25] or after adequate treatment [29]–[31], [36], [40], [44], [45], [48], [50], [51], [54], [55], [57], [59] and 9 cases reached partial recovery [27], [34], [37], [39], [43], [49], [52], [56], [58]. One case did not reach any recovery [53] and 1 case died [33]. In the remaining cases, clinical outcomes were not reported [28], [32], [35], [42], [46], [47], [60], [61].
Discussion
This systematic review included 76 unique cases of yoga-associated adverse events. Most adverse events affected the musculoskeletal, nervous, or visual system. More than half of the cases for which clinical outcomes were reported reached full recovery, 1 case did not recover at all, and 1 case died. Headstand was by far the most often cited yoga posture; and Pranayama and Bikram yoga were the yoga practices that were most often associated with adverse events.
Incidence rates of adverse events associated with yoga are best estimated from large prospective surveys of practitioners. However, these data are rare. In a small survey in 110 Finnish Ashtanga Vinyasa Yoga practitioners, 62% of respondents reported at least one yoga-related musculoskeletal injury, mainly sprains and strains [62]. About half of those reported full recovery, the other half partial recovery. Ashtanga Vinyasa Yoga is a physically demanding yoga style that uses standardized sequences of physical yoga postures with synchronized breathing [62]. More recently, in a large national survey, 78.7% of about 2500 Australian yoga practitioners indicated that they had never been injured during yoga [63]. The remaining practitioners mainly reported minor injuries. 4.6% of respondents had been injured in the past 12 months; 3.4% reported injuries that occurred under supervision. In accordance with the present systematic review, the postures that were most commonly associated with injuries were headstand, shoulder stand and variations of the lotus pose [63]. A survey in more than 1300 mainly North American yoga teachers and therapists found that respondents considered injuries of the spine, shoulders, or joints the most common; many respondents regarded yoga as generally safe and associated adverse events with excessive effort, inadequate teacher training, and unknown medical preconditions [64]. Systematic reviews on clinical trials on yoga interventions generally found insufficient reporting of safety data [65]–[68]. However, if adverse events were reported, they could mostly be classified as non-serious [65]–[67].
Out of 76 cases in the present review, 1 fatality was reported [33]. However, the practice described was “voluntary mouth-to-mouth Yoga breathing exercises”, which can hardly be characterized as a typical yoga practice. This practice is not described in any standard handbook of yoga practices [1], [69]. Moreover, postmortem toxicological studies revealed significant levels of long-acting barbiturates that can be argued to be at least partially responsible for her death. Another case report reported a neuropathy being caused by falling asleep in a seated forward bend due to opioids and tricyclic antidepressants [57]. As yoga requires awareness and concentration [70], [71], it is recommended that practitioners abstain from using alcohol or recreational drugs during practice in order to avoid adverse events.
Several of the reported adverse events occurred in yoga teachers [27], [32], [45], who can be assumed to practice more intensely and more often than non-teachers. The yoga postures that were most often associated with adverse events were headstand, shoulder stand, postures that required putting 1 or both feet behind the head, and variations of the lotus position. All these postures can be considered advanced postures that should normally not be practiced by beginners or individuals with medical preconditions [1]. So-called inversions like headstand and shoulder stand are often regarded as a special category of yoga postures that should be practiced only by experienced practitioners, with extreme care. [1], [72]. Two of the 3 cases who had practiced shoulder stand [36], [52] and 8 of the 10 cases that had practiced head stand [25], [32], [35], [37], [38], [46], [52], [53] reported orbital adverse events, mainly glaucomatous symptoms. It has been reported that headstand induces a twofold increase in intraocular pressure [73]. However, intraocular pressure returned to baseline values immediately after headstand and no association of regular yoga practice with chronically increased intraocular pressure was found [73]. Therefore, beginners should be exceedingly cautious with inversions, which may be contraindicated for individuals with a history or positive family history of glaucoma.
Voluntary vomiting is a common Kriya or cleansing technique in traditional yoga [69]. It is however very rarely practiced in North America or Europe [2]. As a case of intermittent reflux symptoms [27] and another one of dental erosion [48] – both of which originated from India – can be assumed to be directly related to regular vomiting, and the postulated cleansing properties of the practice are not in accordance with biomedical science, this practice should be discouraged in general.
Further, 4 adverse events were associated with yoga breathing, or pranayama. While gentle forms of yoga breathing, such as the relaxed abdominal breath, may be appropriate for beginners, extreme forms that involve holding or forcing the breath are considered an advanced yoga practice that should not be done by those new to yoga. [1], [22], [74]. None of the respective case reports stated the length of practice of the affected individual [40], [41], [54], [55]. Yoga practitioners should be advised to be careful when practicing pranayama and perhaps not start practicing forceful techniques such as Kapalabathi, i.e. a practice that resembles hyperventilation, before they have gained a considerable body control and have mastered easier breathing techniques [1], [74]. People with medical conditions should consult their physician regarding the appropriateness of extreme breathing techniques.
Bikram yoga is a modern yoga style that includes traditional Hatha yoga practices in a room heated to 105°F with a humidity of 40% [75]. Bikram yoga is a very intense physical yoga practice that includes forceful exercise and competition [75]. At least 1 of the 3 Bikram yoga-associated adverse events, a hyponatriaemia due to excessive fluid replacement after intensive sweating [51], can be directly related to the specific conditions in Bikram yoga and cannot be transferred to other yoga styles. The extreme heat and intensity of the Bikram yoga practice may make this style of yoga inappropriate for older adults and people with medical conditions.
The majority of cases were female and the number of reports published each year gradually increased from 1969 to 2012. These findings reflect general characteristics of yoga practitioners. About 75% of all yoga users are female [76], [77] and yoga is gaining increased popularity over time: in 1994, about 5 million American Adults practiced yoga [78], by 2002, more than 10 million [7], and by 2007, more than 13 million [6]. Most cases included in this review originated from the USA. While there are no reliable data on prevalence of yoga use outside the USA, this might reflect a presumable higher prevalence of yoga use in the USA compared to most other countries worldwide [79].
There are several limitations in this review. Only case reports and case series that were published in peer-reviewed journals were included to ensure a certain quality of assessment and reporting. However, cases that were published in grey literature might have enhanced the findings of the review. Moreover, the quality of reporting in the included case reports and case series generally was low. Only few reports described the specific yoga form practiced or the practice experience of the case. Even more critically, for about 2 thirds of reported cases, no information on clinical outcomes was provided. This makes it hard to estimate the number of non-recovered or only partially recovered cases; information that is crucial for assessing the safety of yoga. Case reports and case series are anecdotal by nature. Therefore, this systematic review is unable to estimate the total number or frequency of adverse events associated with yoga.
Conclusions
As any other physical or mental practice, yoga is not without risk. However, given the large number of practitioners worldwide [6]–[8], only relatively few serious adverse events have been reported in healthy individuals. Therefore, there is no need to discourage yoga practice for healthy people. It has however been stressed that yoga should not be practiced as a competition and that yoga teachers and practitioners should never push themselves (or their students) to their limits [9]. Beginners should avoid advanced postures such as headstand or lotus position and advanced breathing techniques such as Kapalabathi. Practices like voluntary vomiting should perhaps be avoided completely.
As yoga has been shown to be beneficial for a variety of conditions [65], [66], [68], it can also be recommended to patients with physical or mental ailments, as long as it is appropriately adapted to their needs and abilities and performed under the guidance of an experienced and medically trained yoga teacher. Especially, patients with glaucoma should avoid inversions and patients with compromised bone and other musculoskeletal disorders should avoid forceful or competitive yoga forms. Yoga should not be practiced while under the influence of psychoactive drugs.
Author Contributions
Conceived and designed the experiments: HC GD. Performed the experiments: HC. Analyzed the data: HC CK. Wrote the paper: HC CK.
References
- 1.
Iyengar BKS (1966) Light on yoga. New York: Schocken Books.
- 2.
Feuerstein G (1998) The yoga tradition. Prescott: Hohm Press.
- 3.
De Michaelis E (2005) A history of modern yoga: Patanjali and western esotericism. London, UK: Continuum International Publishing Group.
- 4.
Hari Y (2006) Hatha Yoga Pradipika. Miramar, FL: Nada Productions, Inc.
- 5.
Macy D (2008) Yoga journal releases 2008 “Yoga in America” market study. Yoga Journal. Available: http://www.yogajournal.com/advertise/press_releases/10. Accessed 20 February 2013.
- 6.
Barnes PM, Bloom B, Nahin RL (2008) Complementary and alternative medicine use among adults and children: United States, 2007. Natl Health Stat Report: 1–23.
- 7.
Barnes PM, Powell-Griner E, McFann K, Nahin RL (2004) Complementary and alternative medicine use among adults: United States, 2002. Adv Data: 1–19.
- 8.
Dangerfield A (2009) Yoga wars. BBC news magazine. 23 January 2009. Available: http://news.bbc.co.uk/1/hi/7844691.stm. Accessed 20 February 2013.
- 9.
Krucoff C (2003) Insight from Injury. If the practice of hatha yoga was meant to heal, why are so many yogis getting hurt? Yoga Journal May/June 2003: 120–124; 203.
- 10.
McCall T (2013) Working with Students Who Have Yoga Injuries, Part 1. Yoga Journal. Available: http://www.yogajournal.com/for_teachers/2634. Accessed 20 February 2013.
- 11.
Broad WJ (2012) How yoga can wreck your body. The New York Times. 5 January 2012. Available: http://news.bbc.co.uk/1/hi/7844691.stm. Accessed 20 February 2013.
- 12.
Grant D (2012) The 10 best responses to New York Times Magazine’s yoga article. New York Observer. December 12, 2012. Available: http://observer.com/2012/01/the-10-best-responses-to-new-york-times-magazine-yoga-article/. Accessed 20 April 2013.
- 13. Barsky AJ, Hartman EE (1997) A 37-year-old man with multiple somatic complaints. Journal of the American Medical Association 278: 673–678.
- 14. Biswas R, Dalal M (2003) A yoga teacher with persistent cheilitis. Int J Clin Pract 57: 340–342.
- 15. Farooq MU, Martin JH, Andary MT (2008) Unusual presentation of hereditary neuropathy with liability to pressure palsies. J Brachial Plex Peripher Nerve Inj 3: 2.
- 16. George HR (1970) A case of the Kleine-Levin syndrome of long duration. Br J Psychiatry 117: 521–523.
- 17. Kennedy RB Jr (1976) Self-induced depersonalization syndrome. Am J Psychiatry 133: 1326–1328.
- 18. Lovell-Smith HD (1985) Transcendental meditation and three cases of migraine. N Z Med J 98: 443–445.
- 19. Schievink WI, Maya MM, Chow W, Louy C (2007) Reversible cerebral vasoconstriction in spontaneous intracranial hypotension. Headache 47: 284–287.
- 20. Yochum TR, Barry MS (1997) Bone marrow edema caused by altered pedal biomechanics. J Manipulative Physiol Ther 20: 56–59.
- 21. Caso V, Paciaroni M, Bogousslavsky J (2005) Environmental factors and cervical artery dissection. Front Neurol Neurosci 20: 44–53.
- 22. Hillsman D, Sharma V (2005) Yoga and pneumothorax. Chest 127: 1863.
- 23. Kugler J (1972) Neurologische Störungen nach Yogaübungen. Med Klin 67: 1195.
- 24. Hwa C, Brauer JA, Mundi JP, Wu JM, Patel RR, et al. (2011) Exercise-induced progressive pigmentary purpura of the forehead. J Am Acad Dermatol 65: e149–150.
- 25. Bertschinger DR, Mendrinos E, Dosso A (2007) Yoga can be dangerous–glaucomatous visual field defect worsening due to postural yoga. Br J Ophthalmol 91: 1413–1414.
- 26. Bianchi G, Cavenago C, Marchese M (2004) Can the practice of yoga be dangerous? Considerations over a case of epiphyseal separation of the distal tibia in a teenager. Journal of Orthopaedics and Traumatology 5: 188–190.
- 27. Biswas R, Paul A, Shetty KJ (2002) A yoga teacher with persistent reflux symptoms. Int J Clin Pract 56: 723.
- 28. Brauer JA, Mundi J, Chu J, Patel R, Meehan S, et al. (2011) Progressive pigmentary purpura. Dermatol Online J 17: 14.
- 29.
Chakraborty J, Umakanth S, Vikram K, Yashodhara BM (2011) A subcutaneous cord over the chest in Mondor’s disease. BMJ Case Reports.
- 30.
Choi Y, Lee D (2009) A case of rectus sheath hematoma caused by yoga exercise. Am J Emerg Med 27: 899 e891–892.
- 31. Chusid J (1971) Yoga foot drop. Journal of the American Medical Association 217: 827–828.
- 32. Cohen JA, Char DH, Norman D (1995) Bilateral orbital varices associated with habitual bending. Arch Ophthalmol 113: 1360–1362.
- 33. Corrigan GE (1969) Fatal air embolism after Yoga breathing exercises. JAMA 210: 1923.
- 34.
Dacci P, Amadio S, Gerevini S, Moiola L, Del Carro U, et al.. (2012) Practice of yoga may cause damage of both sciatic nerves: a case report. Neurol Sci.
- 35. de Barros DS, Bazzaz S, Gheith ME, Siam GA, Moster MR (2008) Progressive optic neuropathy in congenital glaucoma associated with the Sirsasana yoga posture. Ophthalmic Surg Lasers Imaging 39: 339–340.
- 36. Fahmy JA, Fledelius H (1973) Yoga-induced attacks of acute glaucoma. A case report. Acta Ophthalmol (Copenh) 51: 80–84.
- 37. Fong KY, Cheung RT, Yu YL, Lai CW, Chang CM (1993) Basilar artery occlusion following yoga exercise: a case report. Clin Exp Neurol 30: 104–109.
- 38. Gallardo MJ, Aggarwal N, Cavanagh HD, Whitson JT (2006) Progression of glaucoma associated with the Sirsasana (headstand) yoga posture. Adv Ther 23: 921–925.
- 39. Hanus SH, Homer TD, Harter DH (1977) Vertebral artery occlusion complicating yoga exercises. Arch Neurol 34: 574–575.
- 40. Johnson DB, Tierney MJ, Sadighi PJ (2004) Kapalabhati pranayama: breath of fire or cause of pneumothorax? A case report. Chest 125: 1951–1952.
- 41. Kashyap AS, Anand KP, Kashyap S (2007) Complications of yoga. Emerg Med J 24: 231.
- 42. Khalil PN, Ladurner R, Mussack T, Hallfeldt K (2008) [Traumatic lymphocele after yoga exercise]. MMW Fortschr Med 150: 39.
- 43. Kim NN, Wickless HW (2010) Pustular eruption on face. J Fam Pract 59: 399–401.
- 44. Kohanzadeh S, LaFrenierre S, Nasseri Y, Silberman A, Kulber D (2012) Myositis ossificans of the forearm after yoga. Am Surg 78: E361–363.
- 45. Lu JS, Pierre JM (2007) Psychotic episode associated with Bikram yoga. Am J Psychiatry 164: 1761.
- 46. Margo CE, Rowda J, Barletta J (1992) Bilateral conjunctival varix thromboses associated with habitual headstanding. Am J Ophthalmol 113: 726–727.
- 47. Mattio TG, Nishida T, Minieka MM (1992) Lotus neuropathy: report of a case. Neurology 42: 1636.
- 48. Meshramkar R, Patil SB, Patil NP (2007) A case report of patient practising yoga leading to dental erosion. Int Dent J 57: 184–186.
- 49. Nagler W (1973) Vertebral artery obstruction by hyperextension of the neck: report of three cases. Arch Phys Med Rehabil 54: 237–240.
- 50. Patel SC, Parker DA (2008) Isolated rupture of the lateral collateral ligament during yoga practice: a case report. J Orthop Surg (Hong Kong) 16: 378–380.
- 51.
Reynolds CJ, Cleaver BJ, Finlay SE (2012) Exercise associated hyponatraemia leading to tonic-clonic seizure. BMJ Case Rep 2012: pii: bcr0820114625.
- 52. Rice R, Allen RC (1985) Yoga in glaucoma. Am J Ophthalmol 100: 738–739.
- 53. Shah NJ, Shah UN (2009) Central retinal vein occlusion following Sirsasana (headstand posture). Indian J Ophthalmol 57: 69–70.
- 54. Sharma H, Shekhawat NS, Bhandari S, Memon B, Memon MA (2007) Rectus sheath haematoma: a rare presentation of non-contact strenuous exercises. Br J Sports Med 41: 688–690.
- 55. Tamarin FM, Conetta R, Brandstetter RD, Chadow H (1988) Increased muscle enzyme activity after yoga breathing during an exacerbation of asthma. Thorax 43: 731–732.
- 56. Vogel CM, Albin R, Alberts JW (1991) Lotus footdrop: sciatic neuropathy in the thigh. Neurology 41: 605–606.
- 57. Walker M, Meekins G, Hu SC (2005) Yoga neuropathy. A snoozer. Neurologist 11: 176–178.
- 58. Yeh TS, Chang KV, Wang TG (2011) Common Flexor Tendon Tear Following Yoga and Local Corticosteroid Injections: A Case Report. Journal of Medical Ultrasound 19: 91–94.
- 59. Yorston GA (2001) Mania precipitated by meditation: A case report and literature review. Mental Health, Religion and Culture 4: 209–213.
- 60. Le Corroller T, Vertinsky AT, Hargunani R, Khashoggi K, Munk PL, et al. (2012) Musculoskeletal injuries related to yoga: Imaging observations. American Journal of Roentgenology 199: 413–418.
- 61. Sinaki M (2013) Yoga spinal flexion positions and vertebral compression fracture in osteopenia or osteoporosis of spine: case series. Pain Pract 13: 68–75.
- 62. Mikkonen PP, Pedersen P, McCarthy, P W (2008) A survey of musculoskeletal injury among Ashtanga Vinyasa yoga practitioners. Int J Yoga Therap 18: 59–64.
- 63. Penman S, Cohen M, Stevens P, Jackson S (2012) Yoga in Australia: Results of a national survey. Int J Yoga 5: 92–101.
- 64. Fishman LM, Saltonstall E, Genis S (2009) Understanding and preventing yoga injuries. Int J Yoga Therap 19: 47–54.
- 65. Cramer H, Lange S, Klose P, Paul A, Dobos G (2012) Yoga for breast cancer patients and survivors: a systematic review and meta-analysis. BMC Cancer 12: 412.
- 66. Cramer H, Lauche R, Haller H, Dobos G (2013) A Systematic Review and Meta-analysis of Yoga for Low Back Pain. Clin J Pain 29: 450–460.
- 67. Cramer H, Lauche R, Klose P, Langhorst J, Dobos G (2013) Yoga for schizophrenia: a systematic review and meta-analysis. BMC Psychiatry 13: 32.
- 68. Cramer H, Lauche R, Langhorst J, Dobos G (2012) Effectiveness of yoga for menopausal symptoms: a systematic review and meta-analysis of randomized controlled trials. Evid Based Complement Alternat Med 2012: 863905.
- 69.
Vishnu-devananda S (1988) The complete illustrated book of yoga. New York: Harmony Books.
- 70. Cramer H, Lauche R, Haller H, Langhorst J, Dobos G, et al. (2013) “I’m More in Balance”: A Qualitative Study of Yoga for Patients with Chronic Neck Pain. J Altern Complement Med 19: 536–542.
- 71.
Bussing A, Edelhauser F, Weisskircher A, Fouladbakhsh JM, Heusser P (2011) Inner Correspondence and Peacefulness with Practices among Participants in Eurythmy Therapy and Yoga: A Validation Study. Evid Based Complement Alternat Med 2011.
- 72.
Yoshikawa Y (2013) Everybody upside-down. Let gravity work for you. Inversions are good for your lungs, heart, thyroid, and more. Yoga Journal. Available: http://www.yogajournal.com/practice/214. Accessed 20 April 2013.
- 73. Baskaran M, Raman K, Ramani KK, Roy J, Vijaya L, et al. (2006) Intraocular pressure changes and ocular biometry during Sirsasana (headstand posture) in yoga practitioners. Ophthalmology 113: 1327–1332.
- 74. Sharma VP (2007) Pranayama can be practiced safely. Int J Yoga Therap 17: 75–79.
- 75.
Bikram Yoga College of India (2012) Bikram yoga. Available: http://bikramyoga.com/. Accessed 20 April 2013.
- 76. Birdee GS, Legedza AT, Saper RB, Bertisch SM, Eisenberg DM (2008) Characteristics of yoga users: results of a national survey. J Gen Intern Med 23: 1653–1658.
- 77. Cramer H, Lauche R, Langhorst J, Paul A, Michalsen A, Dobos G (2013) Predictors of yoga use among internal medicine patients. BMC Complement Altern Med 13: 172.
- 78. Cushman A (1994) Guess who’s coming to yoga? Yoga Journal 118: 47–48.
- 79.
Lamb T (2006) Yoga statistics and demographics. Prescott: International Association of Yoga Therapists.