Since the 1020’s researchers have been studying and publishing articles on the results of a Yoga practice. Listed below are some of the research results of Hatha Yoga and specific medical conditions. :
ADHD Eighteen boys with diagnosed attention-deficit/hyperactivity disorder (ADHD) were randomly assigned to either a yoga treatment or a cooperative activities group. After 20 sessions of yoga, the boys showed improvement on a variety of indices, including oppositional behavior, emotional lability, and restlessness or impulsivity. The subjects exhibited a dose/ response curve, with those subjects who participated in additional home practice showing a greater response. The control group showed superior scores on measures of hyperactivity, anxiety, and shyness, as well as social function measures.7
Anxiety A meta-analysis of the research involving yoga interventions for anxiety and related disorders reviewed eight studies conducted during 2004. Overall, this research reported positive results, especially in cases of obsessive-compulsive disorder. However, the authors were quick to point out a generally poor quality of research techniques, inadequacies in methodology, and difficulty comparing studies.8 A Cochrane review of two RCTs that investigated the effectiveness of meditation and yoga on patients with diagnosed anxiety disorders stated that based on the available research, no distinct conclusions can be drawn on the ability of meditation and yoga to be effective for anxiety disorders.9
Asthma To determine the efficacy of Iyengar yoga practice on symptoms and perceived quality of life of people living with asthma, 62 patients with mild to moderate asthma were randomized and divided into two groups. The treatment group performed Iyengar yoga for 4 weeks, and the control group enrolled in a “stretching” program. Both groups underwent spirometry testing and recorded their bronchodilator use, symptoms, and quality of life assessments. At no point in the study did the yoga intervention group show a measured benefit in clinical indices.10 Another small RCT divided 17 subjects into a yoga treatment and a control group. The yoga group engaged in relaxation pranayama (mindful breathing) techniques, yoga postures, and meditation 3 times per week for 16 weeks. Spirometry testing showed little difference between the two groups; however, the yoga group showed improved exercise tolerance and reported relaxation as well as a more positive attitude as measured by questionnaire. This study also showed a trend toward less use of short-acting bronchodilator medication in the yoga group.11
Back pain A 12-week RCT compared viniyoga practice with conventional therapeutic back exercises or a self-help book for 101 patients with chronic low back pain. The yoga group met with one instructor for a weekly 75-minute viniyoga practice. Patients were also encouraged to practice at home daily and were given handouts and an audio CD guide. This group showed greater improvement in functional status, decreased activity restriction, and increased general health compared to the conventional exercise group or the self-help book group at 12 weeks. At 26 weeks post treatment, the conventional exercise and yoga therapy group did not show a significant difference in outcome, though at all points in time, viniyoga therapy appeared to be more effective than the self- care book. The viniyoga benefit also lasted for months after the intervention.12
Cardiovascular disease A systematic literature review of 70 studies published over the past two decades showed a trend toward beneficial changes in metabolic syndrome risk factors such as insulin resistance, lipid profiles, BP, and anthropomorphic indices. The author noted that by controlling risk factors for metabolic syndrome, a regular yoga practice might possibly reduce the risk of cardiovascular disease (CVD). It is important to note that approximately one-third of the reviewed studies were RCTs and that the majority of the others were uncontrolled or nonrandomized controlled clinical trials.4 A 2002 comprehensive review of the literature on the psychophysiological effects of hatha yoga concluded that regular hatha yoga practice and a “yoga lifestyle” have the potential to benefit CVD risk indices.5
Cardiovascular fitness A 50-minute hatha yoga routine burns 2.2 to 3.6 kcal/min, the equivalent a very slow walk. Except in persons who are very deconditioned, this type of yoga practice alone is unlikely to have a significant training effect on cardiovascular fitness, pulmonary function, body composition, or fat metabolism.13 More vigorous forms of power or vinyasa yoga require a higher energy output, depending on the method of teaching and selection of asanas (postures). One recent study demonstrated a 7% increase in VO2 max after previously sedentary subjects practiced 8 weeks of yoga training.13 However, the general consensus is that yoga does not provide the significant cardiovascular stimulus necessary to enhance cardiovascular function.14
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4. Innes KE, Bourguignon C, Taylor AG. Risk indices associated with the insulin resistance syndrome, cardiovascular disease, and possible protection with yoga: a systematic review. J Am Board Fam Pract. 2005;18(6):491-519.
5. Raub JA. Psychophysiologic effects of Hatha yoga on musculoskeletal and cardiopulmonary function: a literature review. J Altern Complement Med. 2002;8(6):797-812.
6. Luskin FM, Newell KA, Griffith M, et al. A review of mind-body therapies in the treatment of musculoskeletal disorders with implications for the elderly. Altern Ther Health Med. 2000;6(2): 46-56.
7. Jensen PS, Kenny DT. The effects of yoga on the attention and behavior of boys with attentiondeficit/ hyperactivity disorder (ADHD). J Atten Disord. 2004;7(4):205-216.
8. Kirkwood G, Rampes H, Tuffrey V, et al. Yoga for anxiety: a systematic review of the research evidence. Br J Sports Med. 2005;39(12):884-891.
9. Krisanaprakornkit T, Krisanaprakornkit W, Piyavhatkul N, Laopaiboon M. Meditation therapy for anxiety disorders. Cochrane Database Syst Rev. 2006;(1):CD004998.
10. Sabina AB, Williams AL, Wall HK, et al. Yoga intervention for adults with mild-to-moderate asthma: a pilot study. Ann Allergy Asthma Immunol. 2005;94(5):543-548.
11. Vendanthan PK, Kesavalu LN, Murthy KC, et al. Clinical study of yoga techniques in university students with asthma: a controlled study. Allergy Asthma Proc. 1998;19(1):3-9.
12. Sherman KJ, Cherkin DC, Erro J, et al. Comparing yoga, exercise, and a self-care book for chronic low back pain: a randomized, controlled trial. Ann Intern Med. 2005;143(12):849-856.
13. Tran MD, Holly RG, Lashbrook J, Amsterdam EA. Effects of Hatha yoga practice on the healthrelated aspects of physical fitness. Prev Cardiol. 2001;4(4):165-170.
14. Clay CC, Lloyd LK, Walker JL, et al. The metabolic cost of Hatha yoga. J Strength Cond Res. 2005;19(3):604-610.