We all know that exercising regularly is good for us-- it keeps weight off, helps keep our cardiovascular system healthy, and keeps our muscles strong and lean. However, have you ever wondered how exercise can impact your immune system and ability to fight off sickness? I thought, now more than ever, would be a great time to share about how exercise can help ward off viruses and colds!
Above, I have pictured what is known as in the Exercise Science world as the "J-shaped Curve." I remember learning about this topic in college and thinking how fascinating it was that exercise can actually protect us from getting sick. As you can see from the graph, when individuals are sedentary (meaning not regularly participating in physical activity), their risk of developing an upper respiratory tract infection is "average." When one begins a moderate exercise program, the risk for getting sick actually goes down! However, when someone pushes it and starts overexercising, the risk for infection actually increases above average. This would be a result of overtraining (what happens when athletes, or anyone for that matter, train so intensely and excessively that it essentially wears them out physically and mentally). This can occur when an individual does not take proper rest days, is exercising at too high of intensities, or exercising for too long of durations (or a combination of all three).
So, how much exercise is the right amount to put my immune system in the best position to fight off colds and viruses? Well, it may differ depending on your goals, lifestyle, age, etc. However, for reference, the American College of Sports Medicine recommends that most adults should participate in moderate aerobic exercise for 150 minutes per week. This is generally interpreted as "30 minutes per day, 5 days per week." Intensity of exercise (light, moderate, or hard) can be quantified in many ways, including using your HR, an RPE scale, or simply recognizing your breathing and sweating patterns and what feels moderate for you. You can read more about the ACSM's guidelines for physical activity here:
So, how exactly does moderate exercise improve the health of your immune system? What are the mechanisms going on here? When engaging in aerobic exercise, your body mobilizes immune cells to enter your bloodstream to go to all different parts of your body. These immune cells released are specifically used to attack viruses, and are ready to act when prompted by our bodies. While circulating, these immune cells are working as an "immunosurveillance" team-- meaning they are on watch and ready for when they need to attack any invading viruses or bacteria that come in their way. This makes us better prepared for when our bodies do become attacked by a foreign infection (all thanks to some exercise!)
Along with an increase in the immune surveillance system occurring, exercise also releases cytokines. Cytokines are proteins involved in immune system regulation, with some specific ones released by exercise including IL-6 and IL-7 (interleukin-6 and interleukin-7). Both of these play an important role in prepping the body to fight infection. IL-6 works to direct immune-attacking cells towards sites of infection, whereas IL-7 promotes production of T-cells, a type of white blood cell that responds directly to infections.
So, next time you need another reason to get off the couch and get moving, remember the impact exercise can have on your immune system! On the other side, if you already exercise and find yourself weak, fatigued, or getting sick frequently, you may need to incorporate more rest time into your schedule! A lot of it, like life, is learning to get outside of our heads and listen to what our bodies need. Chalk up another one for exercise!
To learn more, check out some of the references below.
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By: Maresa Bowen, MS, Personal Trainer & Clinical Exercise Specialist