You’ve been hearing since elementary school P.E. class that physical activity is good for you. (Cue flashbacks to pushup tests and ugly gym class uniforms.)
But did you know that regular exercise also improves your immune system — and can make vaccines more effective?
Here’s the important role that physical activity plays in supporting your immune system’s functions and how you can reap these benefits.
How the immune system works
To understand how exercise supports your immune system, let’s step into the classroom for a quick refresher on how the immune system works.
The immune system protects the body from infection and has two parts: innate and adaptive immunity.
You’re born with innate immunity. Its job is to quickly respond to pathogens that enter your body (such as toxins, bacteria and viruses like COVID-19). The pathogens are flagged by pathogen recognition molecules on our cells that tell the cell to release cytokines and chemokines, which are messenger molecules.
“The cytokines and chemokines trigger your innate immune system, telling it that there’s something going on in your body,” says Dr. Deborah Fuller, a microbiologist at the University of Washington.
Then, the pathogens (along with antigens, which are molecules found on the surface of pathogens) are broken down by our cells and presented to our B and T cells, which triggers the adaptive immune response.
“Antigen-presenting cells gather and break down the pathogens into antigens and present them to the immune system,” says Fuller. “They trigger B cells to produce antibodies that can block an infection and reduce its replication in our bodies. They can also trigger killer T cells that can find and eliminate infected cells from our bodies.”
Once your body resolves an infection, a subset of the B and T cells, called memory cells, stays in your body. Should you get exposed to the same pathogen in the future, these memory cells can quickly activate and shut down the infection before it makes you sick.
“Vaccines fool our bodies into producing these memory cells so they can protect us from future exposure to a real pathogen,” explains Fuller.
How exercise benefits the immune system
“When you exercise, you release cytokines and chemokines,” says Fuller.
This release helps tune up your immune system so that it's better prepared to deal with an infection, making it able respond faster and more effectively.
“Exercise can also naturally modulate so that you’re not over-responding to the infection,” says Fuller.
In other words, physical activity helps your body trigger the right amount of immune response to effectively shut down the infection — instead of an overreactive immune response, which can result in inflammation.
“COVID-19 is a virus of inflammation, which can cause fluid buildup in your lungs, tissue damage and more,” says Fuller.
A recent study shows that serious inflammatory responses to COVID-19 that can cause hospitalization and death were least likely to be found among those who were physically active.
How exercise makes vaccines more effective
Vaccines — including all the COVID-19 vaccines — teach your immune system to create antibodies like an infection does.
The big difference? Vaccines work without making you sick. (You may have some side effects after you get vaccinated, but those are normal signs that your body is building protection.)
Most vaccines protect us from infection by triggering an “antibody response,” but the amount of antibody you produce in response to a vaccine can vary from person to person.
“How strong an antibody response you develop is influenced by your genetics, age, diet and exercise,” says Fuller. “In general, the healthier you are, the stronger your antibody response.”
A strong antibody response following vaccination is most common in younger people as well as those who are fit and healthy. Their immune systems can respond more quickly and strongly to the vaccine.
It’s important to note that the intensity or duration of side effects that you feel after getting a vaccine do not necessarily predict the amount of antibody you will develop post-vaccination. While feeling side effects from a vaccine is a sign that the vaccine is working, there are many factors that influence your reaction to a vaccine.
“If you get a greater reaction, it doesn’t mean you’re developing more antibodies,” says Fuller.
So don’t worry if you do or don’t feel icky post-vaccination; the vaccine is working, as is your immune system.
How much exercise is “enough” to get these benefits?
So, exercise supports your immune system and makes vaccines more effective. But is there a way to quantify how much exercise is enough for your immune system to benefit?
“Any amount of exercise is better than nothing,” says McMullen. “I go back to the standard recommendations of 150 minutes of moderate-intensity exercise or 75 minutes vigorous-intensity exercise per week.”
Those minutes are meant to be broken up in a way that works with your lifestyle and fitness baseline.
And if you’re wondering if a certain type of exercise — be it cardio or strength — best supports your immune system, McMullen reassures that any type of physical activity is beneficial.
“Both activating muscle fibers and increasing blood flow — heart rate — activate immune cells,” says McMullen.
As you get your sweat on, make sure to listen to your body and go at your own pace.
“Too much exercise, called overtraining, might increase risk of infections,” says McMullen.
In fact, a recent study shows that exercising for too long without enough rest can decrease cellular immunity and increase susceptibility to infection.
So, no need to overdo it. Just follow fitness guidelines and remind yourself that as you sweat, you’re doing good for your immune system — and more.
The info in this article is accurate as of the publishing date. While Right as Rain strives to keep our stories as current as possible, the COVID-19 pandemic continues to evolve. It’s possible some things have changed since publication. We encourage you to stay informed by checking out your local health department resources, like Public Health Seattle King County or Washington State Department of Health.