Exercise and Your Immune System

Is there any limit to the benefits of exercise? Most of us know that it increases heart health, lung health, helps relieve symptoms of stress and depression, and makes daily activities easier (all while boosting your mood), among other things. But did you know that exercise increases your immune system as well?

First, let’s start with what the immune system actually is and how it functions. The immune system is not one single thing- it is a complex system made of a web of organs, cells, and proteins that work together to fight illness, speed up healing, and keep your body healthy in general. Your immune system utilizes a variety of strategies which are either innate or acquired. Innate strategies are kind of like your baseline immune system- you have cells that live in your mucus membranes that fight incoming viruses and bacteria due to plasma protein, which act as a barrier to the outside world. Acquired, or adaptive, strategies are due to exposure to illness, and the bodies ability to “remember” those viruses or bacteria, which causes them to respond more efficiently. 

The adaptive nature of the immune system to known threats is the reason vaccines work, as a side note- injecting either inactive or very very small doses of something like measles or the flu causes your immune system to recognize and react to those specific viruses and be able to fight them off if they come across them again. We don’t have vaccines for things like the common cold due to the fact that that virus mutates so quickly, that we never catch the same cold twice, which is why our immune systems are not as easily able to fight them off. You also have cells that live in your mucus membranes that fight incoming viruses and bacteria due to plasma protein, which is important because it can act like a first line of defense before anything enters your body. 

So how does exercise play a role in the function of this complex system? Exercise increases the effectiveness of both your innate and adaptive immune function. Immune cells circulate your body via the bloodstream. Increased heart and lung health help push those cells along more efficiently and more frequently, which is why long-term exercise and overall fitness is important to immune health as it increases heart and lung health. Perhaps more surprisingly though, exercise also helps your immune function in the short term (immediately after) as well.

Your immune system needs time to be able to “patrol” and identify threats within your body, and exercise speeds up that process. Exercise causes your body to pump more blood around your body during and immediately after. By increasing the movement of blood and lymph, which contain white blood cells, you immediately increase the movement of more immune cells from lymph nodes and the spleen into the bloodstream. It also promotes those white blood cells to move to more locations in your body more quickly making it more likely that your immune system will respond faster, giving it more time to identify and fight off viruses and bacteria. 

Not only does exercise get the immune cells moving throughout the body during activity, but it also promotes a lasting presence of these immune cells for up to three hours after exercise is completed. This provides even more extra time for the immune cells to identify unwanted intruders and keep you from getting sick. Therefore, regular exercise throughout the week (even if you haven’t exercised for long enough to drastically increase heart or lung health quite yet) keeps your immune system moving more efficiently. 

It’s also important to note that stress can negatively affect your immune system, and exercise can help alleviate stress. We know that stress can manifest in physical ways- decreasing quality of sleep, promoting bad eating habits, and generally making our body work harder (flight or fight response, anyone?), which are all things that can damage your immune system.. Decreasing the amount of stress you are under means less negative effects from stress on your immune system!

Exercise also helps negate the effects on your immune system that come with aging. As we age, our immune system naturally gets worse. Studies show that adults that exercise drastically slow down the effects of aging on your immune system. Not only that, but exercise has a bigger impact on the immune system health of older adults. Studies also show that exercise has a particularly dramatic influence on the immune system of those with cancer, obesity, inflammatory illness, and diabetes!

The bottom line: exercise decreases your chances of getting sick, both in the long and short term! And you don’t have to perform vigorous exercise. Anything that gets your body moving and your blood pumping is helpful, even if you just go for a walk!