Introduction
Yoga was born thousands of years ago in India as an integrated physical, mental and spiritual practice based on the ancient Vedic Philosophy and is linked to Ayurveda, the system of traditional Indian medicine. During the 20th century, yoga has become increasingly popular outside of India and in recent decades has continued to grow in popularity worldwide as a system to promote health and well-being. While modern yoga focuses on body positions and is sometimes regarded as a type of physical exercise, complete practice should include one or more of the mental or spiritual elements that are traditionally part of yoga, such as relaxation, concentration or meditation. In recent years, scientific research has evaluated the effectiveness of yoga in various aspects of human pathology and its possible underlying mechanisms have also been studied.
This Science Pill summarizes a review that is part of the Cochrane Library, published by the Cochrane Collaboration. It is an international collaboration initiative created with the aim of collecting and evaluating information on the effectiveness and safety of health interventions.
Below the reader will find a description of some significant work from a clinical and basic research point of view.
Musculoskeletal Diseases
Wieland LS, Skoetz N, Pilkington K, Vempati R, D’Adamo CR, Berman BM.
Yoga treatment for chronic non-specific low back pain.
Cochrane Database Syst Rev. 2017;1(1):CD010671. Published 2017 Jan 12. doi:10.1002/14651858.CD010671.pub2
Non-specific low back pain is an extremely common and potentially disabling condition. It is often treated with over-the-counter drugs without a prescription. For chronic low back pain, current guidelines state that physical therapy can be helpful. There is sufficient evidence that yoga, compared to unexercised controls, leads to moderate improvements in back function at three and six months. Yoga may also be slightly more effective for pain at three and six months, but further studies are needed to clarify whether there is any difference between yoga and other back function or back pain related exercises, or whether yoga added to exercise is more effective than exercise alone. Yoga, however, is not associated with serious adverse events.
Lung Diseases
Asthma
Yang ZY, Zhong HB, Mao C, et al.
Yoga for asthma.
Cochrane Database Syst Rev. 2016;4(4):CD010346. Published 2016 Apr 27. doi:10.1002/14651858.CD010346.pub2
Asthma is a common chronic inflammatory disorder that affects about 300 million people worldwide. As a holistic therapy, yoga has the potential to alleviate the physical and psychological suffering of people with asthma and its popularity has expanded globally. Although several clinical studies conducted to assess the effects of yoga practice have reported inconsistent results, evidence has been found in this study that yoga probably leads to some improvements in quality of life and symptoms in people with asthma. There is more uncertainty about the potential adverse effects of yoga and its impact on lung function and drug use.
COPD, chronic obstructive pulmonary disease
Holland AE, Hill CJ, Jones AY, McDonald CF.
Breathing exercises for chronic obstructive pulmonary disease.
Cochrane Database Syst Rev. 2012;10:CD008250. Published 2012 Oct 17. doi:10.1002/14651858.CD008250.pub2
Breathing exercises, including those associated with yoga, aim to modify respiratory muscle recruitment, improve respiratory muscle performance and reduce the feeling of breathlessness in people with COPD. In this study, an improvement in functional exercise capacity was observed in people with COPD compared to no intervention. However, there are no coherent effects on breathlessness or health-related quality of life. Breathing exercises associated with yoga may still be useful to improve exercise tolerance in people with COPD who are unable to undertake physical training.
Cancer
Support for cancer therapy
Cramer H, Lauche R, Klose P, Lange S, Langhorst J, Dobos GJ.
Yoga for improving health-related quality of life, mental health and cancer-related symptoms in women diagnosed with breast cancer.
Cochrane Database Syst Rev. 2017;1(1):CD010802. Published 2017 Jan 3. doi:10.1002/14651858.CD010802.pub2
This interesting study considered a group of patients undergoing chemotherapy cycles due to breast cancer. Although survival rates are steadily increasing, breast cancer is often associated with long-term psychological distress, chronic pain, fatigue and impaired quality of life. Yoga, understood as an ethical lifestyle, spiritual practice, physical activity, breathing exercises and meditation has been shown to improve physical and mental health. There is some evidence to support the recommendation of yoga as a supportive intervention to improve health-related quality of life and reduce fatigue and sleep disorders compared to no therapy, and to reduce depression, anxiety and fatigue compared to psychosocial or educational interventions.
Cardiovascular Diseases
Coronary heart disease and hypertension
Chu P, Gotink RA, Yeh GY, Goldie SJ, Hunink MG.
The effectiveness of yoga in modifying risk factors for cardiovascular disease and metabolic syndrome: A systematic review and meta-analysis of randomized controlled trials.
Eur J Prev Cardiol. 2016;23(3):291-307.
doi:10.1177/2047487314562741
This review helps to strengthen the evidence base for yoga as a potentially effective therapy for cardiovascular and metabolic health. The results support previous reviews of the positive benefits of yoga on primary and secondary prevention of CVD and metabolic syndrome. Two recently published systematic reviews find that there is evidence for yoga with favorable effects on CVD risk factors.
Yoga can provide the same benefits in reducing the risk factor as traditional physical activity such as cycling or fast walking, supporting a previous narrative review. This is significant because individuals who cannot or prefer not to do traditional aerobic exercise could still achieve similar benefits in reducing cardiovascular risk. The evidence supports the accessibility and acceptability of yoga to patients with lower physical tolerance such as those with pre-existing heart disease, the elderly or those with musculoskeletal or joint pain.
The mechanism underlying the therapeutic effect of yoga for cardiovascular disease is not yet clear; studies have suggested that yoga can modulate the function of the autonomic nervous system and beneficially alter sympathetic and parasympathetic activity markers. Through yoga practice, the effects of stress can be reduced, leading to positive impacts on the neuroendocrine state, metabolic and cardio-vagal function, and related inflammatory responses.
Research on basic mechanisms
Peter R, Sood S, Dhawan A.
Spectral Parameters of HRV In Yoga Practitioners, Athletes And Sedentary Males.
Indian J Physiol Pharmacol. 2015;59(4):380-387.
Yoga seems to be able to benefit all components of health, i.e. physical, mental, social and spiritual well-being by incorporating a wide variety of practices. The pathophysiology of many non-communicable diseases recognizes a strong correlation with stress. Stress depresses the immune system and neuro-humoral actions, thus influencing the normal psychological state.
The postulated mechanism of action of yoga is through parasympathetic activation and the associated anti-stress mechanism. It reduces perceived stress and activation of the HPA axis (hypothalamic-pituitary-adrenal cortex) thus improving the general metabolic and psychological profiles.
Heart rate variability (HRV) has been used as an indicator for health and autonomic regulation and, therefore, it seems useful to assess the changes that occur with mind-body practices that facilitate autonomous balance. The studies examined suggest that yoga can influence autonomic cardiac regulation with reduction in heart rate and vagal dominance during yoga practices. It has also been found that regular yoga practitioners have increased vagal tone at rest compared to non- yoga practitioners.
By Claudio Molinari