Inflammation is a defensive reaction against pathogens or irritants and is characterized by the five cardinal symptoms of redness, increased heat, swelling, pain, and impaired function. While acute inflammation is a crucial part of our immune process, there are many instances when persistent inflammation leads to serious health problems. Chronic inflammatory disease is an overall term for a variety of chronic diseases such as rheumatoid arthritis, asthma, chronic heart failure, chronic obstructive pulmonary disease, cystic fibrosis, type 1 and type 2 diabetes mellitus, inflammatory bowel disease (e.g., Crohn’s disease, ulcerative colitis), and multiple sclerosis. Despite common characteristics of systemic inflammation, these disorders have a variety of underlying deficiencies while the precise causes and underlying physiological processes are mostly unknown. In Crohn’s disease, multiple sclerosis, rheumatoid arthritis, and type 1 diabetes, chronic systemic inflammation is related to underlying autoimmune disorders whereby the body’s immune system attacks its own tissues. Emerging research suggests that stress-related disorders are significantly associated with risk of subsequent autoimmune disease (Song et al. 2018).
Studies demonstrate an association between physical inactivity and low-grade systemic inflammation in healthy subjects, while regular exercise protects against diseases associated with chronic low-grade systemic inflammation (Petersen and Pedersen 2005). A study by Martin, Pence, and Woods (2009) suggested that moderate intensity exercise improves the immune response to respiratory viral infections. In a systematic review of the literature, Ploeger and colleagues (2009) investigated the effects of acute and chronic exercise on various inflammatory markers in patients with a chronic inflammatory disease. They reported that while training programs can reduce chronic inflammation in some patients, single bouts of exercise might elicit an aggravated inflammatory response. They suggested that the exercise training-induced response appears highly dependent on the type of disease; the severity of the disease; and the frequency, duration, and intensity of the exercise intervention. The authors also noted that the results of the review reveal a major gap in our knowledge regarding the evidence for safe but effective exercise for patients with a chronic inflammatory disease. A study by Haaland and colleagues (2008) also reported that the intensity of the exercise plays an important role. They suggested that strenuous exercise may cause acute immunologic changes (such as diminished natural killer cell activity), which may predispose to infection in certain individuals.
Relationships between mind and body have gradually become more since the early 1990s, and since Ader and Cohen (1975) coined the term psychoneuroimmunology, a body of evidence on this interaction has been growing. The field of investigation looking specifically at yoga and immune function is still young, and the current body of evidence is small.
A systematic review of randomized controlled trials by Falkenberg, Eising, and Peters (2018) looked at the relationship between yoga and immune functioning. Fifteen studies met their inclusion criteria, and they concluded that, although the existing evidence is not entirely consistent, a general pattern emerged suggesting that yoga can downregulate proinflammatory markers. They suggested that these results imply that yoga may be implemented as a complementary intervention for populations at risk for or already suffering from diseases with an inflammatory component. The authors hypothesized that longer time spans of yoga practice are required to achieve consistent effects, especially on circulating inflammatory markers.
A meta-analysis by Morgan and colleagues (2014) looked at the effects of mind–body therapies (tai chi, qi gong, meditation, and yoga) on the immune system. Thirty-four studies published in 39 articles (total 2219 participants) met the inclusion criteria. The authors concluded that mind–body therapies, both short term and long term, appear to reduce markers of inflammation and influence virus-specific immune responses to vaccinations. These immunomodulatory effects, albeit incomplete, warrant further methodologically rigorous studies to determine the clinical implications of these findings for inflammatory and infectious disease outcomes.
It is well established that psychological stress and depression impair antiviral immune responses and activate innate immunity or markers of inflammation via the sympathetic nervous system and the hypothalamus-pituitary-adrenal axis (Morgan et al. 2014). In chapter 2 of The Physiology of Yoga on the nervous system, we explore in much more detail the role that yoga can play in combating stress and depression.
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References:
Ader, R., and N. Cohen. 1975. “Behaviorally Conditioned Immunosuppression.” Psychosomatic Medicine 37 (4): 333-340.
Falkenberg, R., C. Eising, and M. Peters. 2018. “Yoga and Immune System Functioning: A Systematic Review of Randomized Controlled Trials.” Journal of Behavioral Medicine 41:467-482.
Haaland, D., T. Sabljic, D. Baribeau, I. Mukovozov, and L. Hart. 2008. “Is Regular Exercise a Friend or Foe of the Aging Immune System? A Systematic Review.” Clinical Journal of Sport Medicine 18:539-548.
Martin, S., B. Pence, and J. Woods. 2009. “Exercise and Respiratory Tract Viral Infections.” Exercise and Sport Sciences Reviews 37 (4): 157-164.
Morgan, N., M. Irwin, M. Chung, and C. Wang. 2014. “The Effects of Mind–Body Therapies on the Immune System: Meta-Analysis.” PLOS ONE 9(7): e100903.
Petersen, A., and B. Pedersen. 2005. “The Anti-Inflammatory Effect of Exercise.” Journal of Applied Physiology 98:1154-1162.
Ploeger, H., T. Takken, M. de Greef, and B. Timmons. 2009. “The Effects of Acute and Chronic Exercise on Inflammatory Markers in Children and Adults With a Chronic Inflammatory Disease: A Systematic Review.” Exercise Immunology Review 15:6-41.
Song, H., F. Fang, G. Tomasson, F. Arnberg, D. Mataix-Cols, L. Fernández de la Cruz, C. Almqvist, K. Fall, and U. Valdimarsdóttir. 2018. “Association of Stress-Related Disorders With Subsequent Autoimmune Disease.” JAMA 319 (23): 2388-2400.