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In Post #51, I discussed some basic terminology of the immune systems, how immune system works, and what kinds of issues happen when it does not work.

Things that are in our control to enhance our immunity and also so the immune system does not go haywire are the ones that you have heard about gazillions of time by now and are probably tired of hearing about: Nutrition, Exercise and Lifestyle.

In Post #52, we discussed how to boost your immune system with nutrition.   In this post, let’s focus on how and what type of Exercise can boost the immune system.

Impact of exercise on Immune systems

Quite a bit of research is available on how exercise impacts the immune system, although most of it is about impact of exercise on colds and flu. Based on the available research, here are some theories why exercise helps improve the immunity:

  • Physical activity may help flush bacteria out of the lungs and airways. This may reduce your chance of getting a cold, flu, or other airborne illness.
  • Exercise causes changes in antibodies and white blood cells (the body’s immune system cells that fight disease). These antibodies or white blood cells circulate more rapidly, so they could detect illnesses earlier than they might have before.
  • The brief rise in body temperature during and right after exercise may prevent bacteria from growing. This temperature rise may help the body fight infection more effectively. (This is similar to what happens when you have a fever.)
  • Exercise slows down the release of stress-related hormones. Some stress increases the chance of illness. Lower stress hormones may protect against illness.

Getting a little deeper into the subject, here are some findings from some specific studies:

  1. Exercise can provoke moderate acute elevations in IL-6 exerting anti-inflammatory effects
  2. Exercise increases numbers of Neutrophils, T and B lymphocytes, and NK cells – all key components of the immune system
  3. Exercise improves antigen specific T cell function for better protection from infectious agents and greater immunosurveillance
  4. Exercise enhances a variety of macrophage biology and capacities
  5. Exercise improves gut microbiota,  i.e., the bacteria collection in the gut

But how much exercise should you do?

We have all heard that exercise is good for you.  And, as this blog post is emphasizing, among other things, exercise also enhances the immune system. But how much exercise?

In this study, the researchers examined three groups of people: elite athletes, recreational athletes, and sedentary controls. Their results were kind of interesting:

  • The elite athletes had the most upper respiratory issues (66% got sick).
  • The couch potatoes were next (45% got sick).
  • The recreational athletes were the healthiest (22% got sick).

All kinds of other research has found the same thing, so exercise scientists tend to use a J-shaped curve to model the immune effects of exercise. It looks like this:

immunity vs exercise

So one thing is clear, moderate exercise is significantly better for you than no exercise at all. If you are sedentary, it does not seem to take much to get the benefits of improved immune system. For example, daily walking for one hour at a 60 to 65% maximum heart rate (computed as 220-your age) gets you near the optimal range in the above chart.

From the chart, it is clear that there is a point where the benefit of training stops and the negative effect of over-training on the immune system sets in. This literature review article, goes into much more specifics on the kind of exercise that produces the immune-suppressant, i.e., harmful, response:

  • Relatively long workouts (1.5 hours or more), especially without refueling during the workout.
  • A reasonably high intensity, but not excessively difficult (since you have to be able to keep it up for a while).
  • An inadequate recovery period between workouts.

Basically, the kind of grueling training elite athletes often go through preparing for a competition, such as running a marathon.

This article puts it slightly differently:

No activity is worse than some, while too much may be worse than none at all. The ideal lies somewhere in between – though not necessarily in the middle, but rather smack dab in the “just enough” section. Can “just enough” be quantified? Perhaps it could be quantified using a battery of round-the-clock tests and measurements of anabolic and catabolic hormones, various serum concentrations, lactate build-up, cortisol, testosterone ratios, etc., but that would be expensive, unwieldy, and completely individualized. If you want to avoid over-training, there are some grand, overarching principles to follow, but you’ll also want to pay attention to certain personal, entirely subjective cues.

That’s what my trainer and yoga teachers call “listening to your body”. There are days, when I am feeling physically ragged since I may not have slept well, or I may be catching a virus, or am feeling physically exhausted or whatever.   In such situations, I need to carefully “listen to my body” and either take it easier than usual or just totally skip the session.

Bottom Line

To optimize immune systems, exercise plays a critical role. It only takes a moderate amount of exercise to get the optimal benefit of exercise for improving immune system. For example any of these activities or some combination of these done daily would optimize the immune systems:

  1. walking for 1 hour at a pace of 60-65% of maximum heart rate of approximately 220 minus your age,
  2. An hour long yoga routine,
  3. A strength training session with body weight or light weights could do the trick

On the other hand, extended periods of over-training can compromise and may lead to sub-optimal immune system. It is more difficult to define over-training with objective measures and may depend upon many individual factors.  It is best to listen to your body and develop a subjective feel for what level of exercise may be “just right” for you for optimal immune system.


What are your thoughts on this subject?

Would love to hear from you and learn from you.

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