Is Exercise Medicine?

Despite the resistance of some, I personally continue to insist that exercise plays a vital role in the maintenance of wellness. Exercise has proven to be more than merely a preventative measure that simply maintains a pre-existing state of good health; it is also very therapeutic and can slow or reverse serious illness. And we know much today how exercise can help you to improve your immune system.

I find it strange and disappointing that mice with cancer will spontaneously choose to use an exercise wheel placed in their cage and enjoy measurably improved health outcomes, but that human counterparts will actively resist the prescription of exercise programs and thus lose the proven benefits that they would otherwise accrue.¹⁾Hojman P, Gehl J, Christensen JF, Pedersen BK. Molecular Mechanisms Linking Exercise to Cancer Prevention and Treatment. Cell Metab. 2018 Jan 9;27(1):10-21. doi: 10.1016/j.cmet.2017.09.015. Epub 2017 Oct 19. PMID: 29056514. I just have to ask, “Why is that!?” Why is it that animals will voluntarily do the right thing, but often with only great difficulty will people be coerced to do what is in their own best interests? It reminds me of when all the animals spontaneously showed up on their own to board Noah’s ark after 120 years’ worth of failed attempts to give away free tickets to ride out the coming storm and cataclysmic, worldwide flood!

If exercise is medicinal, how “medicinal” is it? Well, in the aforementioned study involving mice with cancer researchers deprived a control group of mice of having the option to freely exercise on spinning wheels inside their cages.²⁾Hojman P, Gehl J, Christensen JF, Pedersen BK. Molecular Mechanisms Linking Exercise to Cancer Prevention and Treatment. Cell Metab. 2018 Jan 9;27(1):10-21. doi: 10.1016/j.cmet.2017.09.015. Epub 2017 Oct 19. PMID: 29056514. This dramatically reduces their physical activity. These mice were then compared to a matched group of cancerous mice that were granted their very own, private little version of Planet Fitness inside their cages (totally free of charge to them and open 24 hours a day, seven days a week).

The results of the study indicate that tumor growth was reduced in all mice that exercised. In cases of liver and lung cancer, the reduction was 59% and 58% respectively. And in mice with melanoma, tumor growth was reduced by 67%. That’s medicinal enough to grab my attention, how about you? If I had cancer, I would be happy to engage in therapy that had those kinds of proven outcomes. Especially if I didn’t have health insurance, or didn’t want to risk experiencing the known side effects and adverse events associated with standard cancer treatments such as chemotherapy.

At this point, you should probably be asking the questions, “How does exercise actually achieve these amazing immune-enhancing effects?” Before pharmaceutical agents are approved for general use in the public, regulatory requirements typically demand evidence of their mechanism of action. If it’s not a placebo, then you should expect to see some scientific reason that explains exactly why it works to help people. So then, what is it that happens in the body when one exercises that is so beneficial as to consider it to be medicinal? For simplicity, I will narrow the discussion of the known mechanisms whereby exercise improves how the body more successfully fights against disease. The mechanisms are complex and many, so let’s start with one that is not too hard to understand. Relax, I’ll try to make this less complex than your average doctor would!

Role of Natural Killer Cells

One of the important issues we have identified is the role that natural killer (NK) cells have in immune function. NK cells are a sub-type of lymphocytes. They make up about 5-15% of all your lymphocytes, which in turn make up around one-third of all your white blood cells (WBCs). These are the ones that respond to help you fight infection, as opposed to red blood cells (RBCs) which contain the hemoglobin that transports oxygen throughout the circulatory system.

What makes normal functioning NK cells so interesting and important is that they do not require any knowledge, prior instruction, or memory of an invader to identify, attack, and destroy it. No antibodies are required, no previous exposure or vaccinations (just like the conditions presently dominating the SARS-CoV-2 pandemic). If you isolate NK cells from a healthy person and put them into a culture with cancer cells, it only takes a few hours before most of the cancer cells are dead! How this happens is largely beyond the scope of this article. BUT… I will tell you how exercise improves NK cell’s function.

Catecholamines (epinephrine, for example, is one of them) are released into the bloodstream during exercise. NK cells have receptors on their surface that respond favorably to these catecholamines, making NK cells move around more, and become more active in their assault against your body’s enemies (both foreign and domestic). Research showed that after 30 minutes of moderate exertion on a stationary exercise bicycle the number of lymphocytes in the bloodstream increased by 100%.³⁾Graff RM, Kunz HE, Agha NH, Baker FL, Laughlin M, Bigley AB, Markofski MM, LaVoy EC, Katsanis E, Bond RA, Bollard CM, Simpson RJ. β2-Adrenergic receptor signaling mediates the preferential mobilization of differentiated subsets of CD8+ T-cells, NK-cells and non-classical monocytes in response to acute exercise in humans. Brain Behav Immun. 2018 Nov;74:143-153. doi: 10.1016/j.bbi.2018.08.017. Epub 2018 Aug 30. PMID: 30172948. And, the specific sub-type of lymphocytes that increased the most, 400-500%, was the NK cells! Researchers continued taking blood samples, and within only 5 minutes from stopping exercise, about half of all those NK cells had left the bloodstream and entered adjacent tissues looking for a fight to win.

Call to Action

These types of laboratory findings have hopeful implications for the current pandemic, suggesting those who follow the recommended guidelines for regular exercise could reasonably expect to have a much greater margin of safety for their immune function when they are exposed to others around them who are actively shedding viruses (of all types). What those recommendations are, and how one might go about beginning to implement them into daily practice will be the topic of upcoming articles, along with additional encouraging research findings relating to exercise and immune function.

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Franklin V. Cobos II

Franklin initially trained as a medicinal organic synthesis chemist, now he is double board-certified in Anesthesiology and Lifestyle Medicine. In 2011 he decided to move into a country property, and enjoys remodeling his home, building furniture, growing his own food and being involved in his local church.