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Sick All the Time?

While it is difficult to prevent 100% of colds and flu, studies have shown over-exercising and intensified training can actually increase risk of illness.

Exercise the Right Way to Prevent Colds and Flus! 

Exercise, as you already know, is great for many elements of your health–and that includes your immune system! Science has shown that exercise strengthens your body’s defense system through many different pathways; it “improve[s] immune regulation, delaying the onset of age-related dysfunction”, “improve[s] defense activity and metabolic health”, and “has an anti-inflammatory influence.”  

That being said, sometimes exercise can actually hurt–not help–your immune system. 

Over-Exercising and Intensified Training Can Increase Risk of Cold and Flu

Last year, my goal was to improve my cardio. I was doing long, punishing sprint intervals at least twice a week, on top of frequent strength training sessions, and feeling pretty tired and rundown. And I was frequently getting sick. At the time, to be honest, I didn’t think much about the relationship between my exercise regimen and my immune health. Colds are random, right? 

Wrong-ish! While it is difficult to prevent 100% of colds and viral infections, studies have shown that periods of over-exercising and intensified training can actually increase one’s risk of illness. Ask yourself: do you feel energized and strengthened by your exercise sessions? Or do you feel run-down and burnt out? This can be an indication that your immune system is not functioning in top-form.

Moderate Intensity Exercise has Preventative Effect on Cold and Flus

High intensity exercise can have amazing benefits, so it is still a part of my weekly regimen. But I now put a greater emphasis on proper recovery, and I’ve replaced one of my high intensity interval sessions with moderate-intensity exercise. Moderate intensity exercise has been shown in multiple cases to have a preventative effect when it comes to cold and flus. High intensity exercise, when done frequently and without appropriate recovery, can result in over-training and has been shown to result in frequent illnesses and general poor health (poor sleep, malaise, lack of appetite, etc.)–and if you combine overtraining with prolonged calorie restriction, you may be even more likely to get sick! If you’re interested in learning more about different exercise intensities and the effects of over-training, we recommend checking out our Infofit articles. 

What are some other steps you can take to prevent illness during the cold and flu season? 

A very important piece to a healthy immune system is rest and recovery. Sleep, as you undoubtedly already know, is especially important. Studies have shown that even a 25% reduction in sleep time will negatively impact your immune system* (to improve your sleep, check out our Infofit article here). Meditation, as well, has been demonstrated to have a negative correlation with incidences of colds and flus, with similar positive effects to exercise! 

Should I Exercise If I’m Sick?

Another frequently asked question is: should I exercise if I’m sick? According to the Mayo Clinic, mild or moderate exercise when you have a common cold and no fever is probably fine! But if you’re miserable and can’t get out of bed – let yourself rest. You won’t lose progress by taking a couple of days off and some experts say that exercising can actually delay your recovery. 

There are tons of science-backed, low-investment interventions that you can take when it comes to preventing viral infections; check them out here

​​Written by Theresa Faulder, Master’s in English, Certified Personal Trainer and Infofit fitness blog writer.

Works Cited

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Edward R. Laskowski, M. D. (2023, November 18). Tips for working out with a cold. Mayo Clinic.,19%20or%20other%20contagious%20illnesses. 

Exercising when sick can delay recovery and can spread the infection; symptoms above and below neck are a key guideline. Kentucky Health News. (2014, January 17). 

MACKINNON, L. T. (2000). Overtraining effects on immunity and performance in athletes. Immunology and Cell Biology, 78(5), 502–509. 

Nieman, D. C., & Wentz, L. M. (2019). The compelling link between physical activity and the body’s defense system. Journal of Sport and Health Science, 8(3), 201–217. 

Nimmo, M. A., & Ekblom, B. (2007). Fatigue and illness in athletes. Journal of Sports Sciences, 25(sup1). 

Shephard, R. J., & Nieman, D. C. (2007). Moderate-intensity exercise reduces the incidence of colds among postmenopausal women. Yearbook of Sports Medicine, 2007, 134–136. 

Woods, J. A., Keylock, K. T., Lowder, T., Vieira, V. J., Zelkovich, W., Dumich, S., Colantuano, K., Lyons, K., Leifheit, K., Cook, M., Chapman‐Novakofski, K., & McAuley, E. (2009). Cardiovascular exercise training extends influenza vaccine seroprotection in sedentary older adults: The Immune Function Intervention Trial. Journal of the American Geriatrics Society, 57(12), 2183–2191.