Exercise and inflammation
Having worked in the fitness industry for over 15 years and helping people with their weight loss goals, I always wondered what role exercise had on inflammation. In obesity, various mechanisms are thought to contribute to a low grade inflammation within the fat tissue affecting the development of several secondary diseases such as metabolic syndrome, insulin resistance (IR), diabetes, arterial hypertension and asthma (Schmidt et al., 2015).
The study I examined look at levels role of exercise and how it influences the levels of pro-inflammatory cytokines in participants with high vs. low physical activity (Gleeson et al., 2011). The study demonstrated a strong relationship to BMI that may indicate that the decrease in inflammatory molecules may be related to decrease in visceral fat. Interestingly, calorie restriction and fasting has been shown to reduce visceral fat in numerous other studies, as well as subsequent reduction in inflammation (which is an area I am very interested in digging into more). Additionally, physical activity may further mitigate inflammation by improving endothelial function, increasing insulin sensitivity, enhancing liver health and increasing blood vessel growth and blood flow.
An article by Gleeson et. al discusses the anti-inflammatory effects of exercise and explains 3 main mechanisms of action:
- Reduction in visceral mass-as mentioned early, a reduction in visceral mass has an indirect effect of being able to decrease inflammation, since accumulation of fat in the omentum, liver and muscles, as well as the expansion of adipose tissue, results in enhanced production of certain inflammatory mediators. Therefore loss of visceral fat can result in reduction in inflammation.
- Release of IL-6 from working muscles-A fall in muscle glycogen content with exercise signals the muscles to secrete IL-6 (a pro-inflammatory cytokine), which stays high during the duration of exercise. However, this also initiates a rise in anti-inflammatory cytokines IL-10 and IL-1RA to minimize the effects on the tissue. Also, it was interesting that you really need 2.5 hours or more of strenuous exercise to get a significant elevation of IL-6, which may partially explain why marathon runners may have suppressed immune systems.
- Increased levels of cortisol and adrenaline-IL-6 stimulates the release of cortisol, which is smaller doses, can have anti-inflammatory effects. It should be pointed out that too much cortisol secretion from the adrenal glands can create a chronic state of inflammation as well, so this could also be a dose dependent phenomenon.
There also appears to be a strong relationship between exhaustive exercise, such as marathon running, and chronic low-grade inflammation induced by the massive systemic release of several pro-inflammatory cytokines and chemokines, such as IL6 and IL8, G-CSF, although host tissue damage may be restricted by compensatory mechanisms. In conclusion, benefits of regular exercise and physical activity are well observed, but I think more clear direction is needed on the types and intensities as well as the health of the person doing the exercise to understand the impact it may have on inflammation.
Gleeson, M., Bishop, N. C., Stensel, D. J., Lindley, M. R., Mastana, S. S., & Nimmo, M. A. (2011). The anti-inflammatory effects of exercise: mechanisms and implications for the prevention and treatment of disease. Nat Rev Immunol, 11(9), 607-615. doi:10.1038/nri3041
Part 2 of 2: Inflammation and Exercise: friend or foe? (2011, August 25). Retrieved 2018, May 2 from https://inscientioveritas.org/inflammation-and-exercise/ (Links to an external site.)
Schmidt, F. M., Weschenfelder, J., Sander, C., Minkwitz, J., Thormann, J., Chittka, T., . . . Himmerich, H. (2015). Inflammatory cytokines in general and central obesity and modulating effects of physical activity. PLoS ONE, 10(3), e0121971. doi:10.1371/journal.pone.0121971