Just 20 minutes of exercise enough to reduce inflammation, study finds

The long-term health benefits of physical exercise are numerous; they include reducing the risk of cardiovascular disease, improving metabolism and weight control, as well as generally strengthening the heart, muscles, and bones.According to the United States Department of Health and Human Services, a regular dose of physical activity also lowers blood pressure, and reduces the risk of type 2 diabetes and some forms of cancer.

New research, published in the journal Brain, Behavior and Immunity, investigates the benefits of 20-minute exercise sessions on the body's immune system.

Researchers from the University of California-San Diego School of Medicine - led by Suzi Hong, Ph.D., from the Department of Psychiatry and the Department of Family Medicine and Public Health - hypothesized that exercise would improve the body's anti-inflammatory response by activating the sympathetic nervous system.

The sympathetic nervous system helps to increase heart rate, blood pressure, and breathing rate. Physical exercise activates this system to help the body keep up.

During this time, the body releases hormones such as epinephrine and norepinephrine into the bloodstream, which activate the adrenergic receptors of immune cells.

Analyzing the body's immune response to exercise
More specifically, the researchers tested the hypothesis that a single 20-minute session of exercise would be enough to trigger sympathoadrenergic activation, which, in turn, would suppress the production of monocytic cytokines.

Monocytes are a type of white blood cell, or immune cell, that help to fight off bacteria and infections. Cytokines are a type of protein that help other cells to become so-called effector cells, which, in turn, kill off cancerous or infected cells.

TNF is one of these cytokines. TNF can induce cell differentiation and proliferation, but also cell death, including cancerous ones. TNF also has pro-inflammatory properties, which help the body to bring its inflammatory cells to the site of the injury, creating an immunological response.

Inflammation is a necessary part of the body's immune response, but too much inflammation can lead to disease. Chronic inflammation may contribute to diabetes, obesity, celiac disease, arthritis, fibromyalgia, or bowel diseases such as Crohn's disease or ulcerative colitis.To test their hypothesis, the researchers asked 47 participants to walk on a treadmill for 20 minutes at an intensity rate adjusted to suit each individual's fitness level. Hong and team took blood samples from the participants both before and immediately after the exercise sessions.

As little as 20 minutes of exercise reduces inflammation
The results revealed that a 20-minute session of moderate exercise can have anti-inflammatory effects.

The study confirmed the researchers' hypothesis. Exercise did seem to produce an anti-inflammatory cellular response, which could be seen in the reduction of the cytokine TNF.

"Our study found one session of about 20 minutes of moderate treadmill exercise resulted in a 5 percent decrease in the number of stimulated immune cells producing TNF," says Hong.

Although the anti-inflammatory benefits of physical activity are already known to researchers, Hong explains, this study explains the process in more detail.

"Knowing what sets regulatory mechanisms of inflammatory proteins in motion may contribute to developing new therapies for the overwhelming number of individuals with chronic inflammatory conditions, including nearly 25 million Americans who suffer from autoimmune diseases," Hong adds.