Using Exercise To Boost Your Immune System

Everyone is always telling you to exercise and lose weight because it’s “good for you.” But are they just repeating what someone said to them? Or is it because they actually can tell you why it’s absolutely essential for health and well being?According to the 2018Physical Activity Guidelines for Americans, 2nd edition, adults should complete at least 150 to 300 minutes per week of moderate-intensity aerobic exercise. Not only is this optimal forheart health, maintaining a healthy weight, and preventing a myriad of chronic diseases, but now there is evidence to suggest that exercise can also supportyour immune function.

How Does Exercise Improve Immune Function?

Increased circulation of white blood cells

Our immune system is very responsive to exercise. Our white blood cells, the predominant component of our immune system, are concentrated in lymphoid tissues and spleen. We don’t have very many in our general circulation the majority of the time. They are not released into our bloodstream until they are “called” to an area of a potential threat, like bacteria, or other microorganisms. Each bout of “acute exercise,” defined as exercise of moderate-intensity and lasting less than an hour, serves to increase the circulation of immune cells. More specifically, exercise recruits more highly specialized white blood cells, like natural killer cells and T cells, that will find pathogens and destroy them before they can make you sick. Inone study, subjects who took a brisk 45 minute walk exhibited an increase in their number of white blood cells for about three hours after completing the walk. 

Decreased systemic inflammation

Many chronic diseases, are all related to pro- inflammatory processes. While exercise in people with these conditions, will transiently increase the number of circulating white blood cells after a bout of exercise, their immune systems are chronically depressed.Studies have shown that the biggest determination of immune system function is related to a person’sbody mass index (BMI). Gender (greater in females), exercise frequency, age, and smoking status were other important factors in determining immune system response to exercise. 

Consistent exercise, on the other hand, may help reverse some of this chronic inflammation. However, if you are not consistent with exercise, you will not have any lasting effects on your immune function. In order to produce a natural anti-inflammatory effect, exercise  must be completed consistently to continually promote an increase of circulating white blood cells. This summation effect of the  “antioxidant” properties of exercise may be able to decrease the incidence of illness. For example, a study in theBritish Journal of Sports Medicine found that people who participated in aerobic exercise five or more days per week decreased the number of upper respiratory tract infections (like the common cold) by more than 40%. 

What Type of Exercise is Best to Improve Immune System Function?

While there are many different types of exercise that are all important in their own right, aerobic exercise is optimal for boosting immune system function. By doing aerobic exercise, you are able to improve your cardiovascular health by increasing your muscles' ability to use oxygen more efficiently.  Aerobic exercise also decreases blood pressure,increases "good" cholesterol, better controls blood sugar, and helps with weight management, which is also critical for optimal immune function. 

You have many options when it comes to deciding what type of aerobic activity to do. 

Some lower impact options include:

• Swimming
• Water aerobics
• Biking
• Ellipticalling
• Walking 
• Rowing

Higher impact activities include:

• High-intensity interval training (HIIT)
• Running
• Jumping rope
• Step aerobics

According to the 2018Physical Activity Guidelines for Americans, 2nd edition, adults should complete at least 150 to 300 minutes a week of moderate-intensity aerobic exercise. Moderate-intensity means you're working hard enough to be a little out of breath and break a sweat; however, you should still be able to talk.

While that may sound like a lot of time, it's important to remember that your aerobic activity does not need to happen all at once. Break it up however you need to! That could mean 15 minutes twice a day five days per week, or you can do an hour a day for three days per week. Breaking the time up into smaller chunks can seem less daunting and make your exercise goals seem more achievable. 

Is Exercise Ever Bad for the Immune System? 

Like anything, you can always have too much of a good thing. Prolonged exercise causes exercise-induced muscle tissue injury and can actually elicit an immune response to try to Prolonged and intense exercise can actually increase your risk of illness, especially when other stressors to the immune system, like high stress or sleep deprivation, are part of the equation. For example, in agroup of 2311 endurance runners, about 13% reported some sort of illness within a week after the Los Angeles marathon compared with only 2.2% of recreational runners, and about 40% of these runners reported at least 1 illness during the 2 months prior to the race. 

 8 Ways to Make Sure You Are Not Overtraining:

1. Make sure you have an individualized training or exercise plan that allows for adequate sleep, nutrition, and hydration. 
2. Don’t change your training load by more than 10% in a single week. For example, if you are a runner trying to increase your running distance, only increase your mileage per week by 10% or less. 
3. Monitor for early signs of overtraining and/or illness, and don’t exercise when you feel sick. 
4. Minimize exposure to germs by avoiding crowded places and exercising in crowded or poorly-ventilated facilities. 
5. Make sure you are on a regular sleep schedule with good sleep hygiene practices, like avoiding screen-time before bed. 
6. Avoid excessive alcohol.
7. Ensure you are eating a well-balanced diet to maintain a healthy weight while also giving your body enough fuel for your exercise load. 
8. Follow stress management techniques and develop healthy coping strategies for life stressors and negative emotions. 

Conclusion

Like everyone keeps saying, exercise is a critical piece of optimal health. Not only is it involved in weight management, chronic disease prevention, and heart health, but it is now tied to optimal immune system function, which is very important especially now. Participate in consistent moderate-intensity aerobic exercise for at least 150 minutes each week in order to increase white blood cell circulation and cumulatively decrease systemic inflammation for chronic disease prevention, including obesity. Listen to your body for signs and symptoms of overtraining, and skip the gym on days that you’re feeling excessively tired to feel like you may be getting sick. You can avoid this by not increasing your exercise load by more than 10% a week, eating a balanced diet, managing stress, and getting enough sleep. Your immune system will thank you for it. 

Note: Consult your physician before beginning a new diet or exercise program or introducing significant changes to your current regimen.

Dr. Amanda Anderson, PT, DPT, MS

Orthopedic Board-Certified Specialist