Movement Should Boost Our Immunity
Is your exercise routine helping or hurting your susceptibility to illness?
I recently came down with a cold. It wasn’t terrible, just a change of season sore throat and stuffy head kind of cold. I continued to exercise through it for the first few days. I definitely felt more fatigued, so I kept the intensity and duration of my workouts low, and I took an extra rest day. As I started to feel better, I ramped up my exercise again and got to thinking a lot about the immune system and how it is influenced by our movement routines.
Ideally, how should one exercise to strengthen the immune system? Can exercise have a negative effect on immunity? Is it okay to workout when I have a cold?
In looking for answers to these questions, I found the following principles to be not only supported by research, but also consistent with what I’ve seen in my professional work with athletes.
Our immune system is directly affected by each bout of exercise.
Exercise is perceived as traumatic to our bodies, so there is an immediate 50–100% elevation of white blood cells to repair our tissues post workout. Within 30 minutes of completing exercise, however, cortisol remains elevated and our white blood cell count falls 30–50% below normal levels. It stays here (immune system depression) for 3–24 hours before returning to its pre-exercise state.
Exercise performed at higher intensities and/or for longer durations causes lasting immune system depression.
Exercise lasting >1.5 hours and/or exercise performed at >60% VO2max without food intake results in lasting immune system depression. Prolonged (>1 week) increases in training volume and/or intensity are correlated with increased rates of upper respiratory tract infections. Illness is also more prevalent in the first 1–2 weeks post race or competition.
An athlete’s response to a training plan will depend on how well it is structured and progressed.
When training overload is properly progressed and followed by a taper period prior to competition, athletes exhibit “super-compensation” of the immune and other systems resulting in enhanced performance. A typical pattern during training might be 2–3 weeks of progressive build followed by a“recovery” week of lighter exercise. Prolonged muscle soreness, excessive fatigue, and decreased heart rate response to exercise can all be indicators of overtraining and immune system depression.
Lifestyle factors are important mediators of our immune system’s response to exercise.
Nutrition: intake of carbohydrates, proteins, and antioxidants during and after bouts of exercise can modify the release of stress hormones and therefore alter the immune system response.
Sleep: sleep quality and quantity is an essential mediator of the body’s response to exercise. Many professional athletes sleep 10–12 hours a night to allow their system adequate time to repair tissue, restore mental acuity, improve reaction times, and optimize energy utilization.
Restorative practices: manual soft tissue work by a physical therapist or massage therapist, as well as compression technology, cryotherapy, and other recovery technologies play an important role in bolstering the body’s recovery and restoration mechanisms.
Chronic moderate exercisers have the strongest immune systems.
Moderate intensity exercise (50–70% VO2max) induces smaller fluctuations in immune system response compared to high intensity exercise (>70% VO2max) and long bouts of continuous exercise. Those who exercise 2 or more days per week have lower rates of infection compared to those who are sedentary.
As a sports medicine physical therapist and recreational athlete for life, I think it is essential that our movement routines support and strengthen our immune health. Consider these takeaways:
Yes, it’s okay to continue exercising when you have a cold!
It may in fact boost your immune response if the intensity and duration are kept low to moderate. Avoid exercise if you have a fever, lower respiratory symptoms, muscle/joint aching, or other more serious symptoms.
Pay attention to how long you feel fatigued and/or sore following a bout of exercise.
These are indicators that your immune system is still depressed. Tracking heart rate variability is helpful for determining when your body and nervous system are recovered.
Make sure your higher intensity and/or longer duration workouts are designed with purpose.
They should always be followed by lighter periods of training to avoid prolonged immune system depression.
Don’t jump right back into training after a competition or race!
Give yourself at least 1–2 weeks of “active recovery” time and focus on flexibility/mobility, soft tissue massage, sleep, nutrition, and restorative exercise such as yoga.
You don’t have to be “training” for a race or competition to exercise in a healthy way.
In fact, you are doing your immune system a favor by NOT over-exercising! For healthy immunity and overall longevity, focus on being active for at least 30 minutes most days of the week, varying your modes of exercise, sleeping well, eating a balanced diet of whole foods, and helping your body recovery with massage, dynamic stretching, and compression.
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Nieman, D., Henson, D., Austin, M., and S DC, Henson DA, Austin MD and Sha, W. (2011). Upper respiratory tract infection is reduced in physically fit and active adults. British Journal of Sports Medicine, 45(12), 987–992.
Nieman, D. (1994). Exercise, upper respiratory tract infection, and the immune system. Med. Sci. Sports Exerc. 26(2), 128–139.
Peake, J., Neubauer, O., Walsh, N., & Simpson, R. (2017). Recovery of the immune system after exercise. Journal of Applied Physiology, 122(5), 1077–1087.
Spence, L. et al. (2007). Incidence, etiology, and symptomalogy or upper respiratory illness in elite athletes. Med. Sci. Sports Exerc. 39(4), 577–586.