Could exercise be a key ingredient in preventing bacterial and viral infections and boosting your immune system?

It turns out regular physical activity does play a role in keeping you healthy and preventing illnesses. That’s because exercise contributes to your overall health, which may help support your immune system’s functions.

This article explains the theories behind how exercise can support your immune system and gives some insight into whether you should work out when you’re sick.

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In short, yes. Exercise benefits your body in a number of ways, and boosting your immunity is just one of those. But there is one important caveat: The frequency, duration, and intensity of your workouts matter.

Research shows that when it comes to boosting your immunity, moderate-intensity exercise is best (1).

In general, exercising at a moderate to vigorous intensity for 60 minutes or less is optimal for the immune-boosting benefits of exercise. If you do this daily or almost daily, your immune and metabolic systems continue to strengthen, building on previous gains (2).

On the other hand, prolonged high intensity training — especially without appropriate rest between sessions — can suppress your immune system (2).

This is an important consideration if you’re a competitive athlete or are training for an endurance events like a marathon. In those cases, take extra care to give your body ample recovery time.

Before getting into the ways physical activity may help your immune system, it’s important to discuss how much exercise you likely need for general health.

According to the U.S. Department of Health and Human Services (HHS), most adults should get at least 150–300 minutes of moderate-intensity aerobic activity or 75 minutes of vigorous physical activity each week (3).

The HHS also recommends doing at least 2 days per week of muscle-strengthening activities involving all major muscle groups in your legs, hips, back, abdomen, chest, shoulders, and arms.

Being active most days of the week is an excellent goal to benefit your overall health and well-being. It’s also a great place to start if you want to work toward boosting your immune system.

A healthy immune system protects your body from bacteria, viruses, and other pathogens you encounter daily.

Here are 6 ways exercise may help your immune system.

1. Exercise stimulates cellular immunity

According to a 2019 research review, moderate-intensity exercise can stimulate cellular immunity by increasing the circulation of immune cells in your body. This helps your body better prepare for a future infection by detecting it earlier (2).

Researchers found that performing aerobic exercise at a moderate to vigorous intensity for less than 60 minutes (an average of 30–45 minutes) increases the recruitment and circulation of the immune system’s best defensive cells (2).

These findings indicate that regular exercise can enhance immune defense activity by making you more resistant to infection and better equipped to deal with infectious agents that have already gained traction in your body (4).

2. Exercise raises body temperature

Unless you’re moving at a snail’s pace, your body temperature will increase during most forms of exercise and will stay elevated for a short time after you complete a workout (5).

Why is this significant? It’s a commonly held belief that this brief rise in body temperature both during and after exercise may prevent bacteria from growing and help your body better address an infection, similarly to how a fever works.

Still, it’s important to note that this claim lacks evidence-based support.

While this temporary temperature rise is not as significant as the increase you experience with a fever, it still may be beneficial to your immune system.

3. Exercise helps you sleep better

Regular physical activity can contribute to better overall sleep quantity and quality (6).

This is great news since sleep loss can negatively affect certain parts of the immune system (7).

Some research points to a higher risk of infection and development of cardiovascular and metabolic disorders due to a reduction in antibodies and the production of inflammatory cytokines in people with a modest amount of sleep loss (8).

4. Exercise decreases risk of heart disease, diabetes, and other diseases

Exercises can reduce cardiovascular risk factors, prevent or delay development of type 2 diabetes, increase HDL (good) cholesterol, and lower resting heart rate (9, 10, 11, 12).

Having one or more of these conditions may make it more difficult for your immune system to ward off infections and viral illnesses such as COVID-19 (13).

5. Exercise decreases stress and other conditions such as depression

There’s a reason people like working out after a long day at work: It helps decrease stress.

More specifically, moderate-intensity exercise can slow down the release of stress hormones while positively influencing the neurotransmitters in the brain that affect mood and behavior (14, 15, 16).

Furthermore, regular exercise may offer a protective benefit against stress — meaning that exercise helps you proactively handle stressors with more resilience and a better mood (17, 18).

According to some research, stress and depression can have a dramatic impact on the regular function of the immune system, leading to a low chronic inflammation status that favors infections, diseases, and other illnesses (19).

6. Exercise reduces inflammation

Inflammation is a normal immune system response that your body uses to address pathogens or toxins.

Acute inflammation isn’t necessarily a problem, but when that acute response remains uncontrolled, it can become chronic and potentially lead to a host of inflammatory diseases (20).

Research has shown that exercise can reduce inflammation and keep that immune response in check — but exercise intensity matters (21).

Studies suggest that moderate-intensity exercise reduces inflammation, while prolonged bouts of high intensity exercise can actually increase inflammation (22).

The takeaway? Moderate exercise with appropriate rest periods can maximize the effectiveness of your body’s inflammatory immune response, lowering your risk of chronic inflammation.


Regular exercise can result in better sleep, improved moods, lower stress levels, and increased circulation of immune cells in your body — all factors that contribute to a healthy immune system.

We hear about the importance of a strong immune system all the time, especially when it comes to preventing viruses, infections, and other diseases.

But what exactly is the immune system, and how critical is it to your overall health?

For starters, your immune system is made up of cells, organs, tissues, and even reflexes such as your cough reflex. Its main job is to repel or limit infections and other diseases.

When your body detects an antigen — something harmful or foreign, such as a virus, a toxin, or bacteria — your immune system kicks into gear to protect you by attacking it. This is called an immune response (23).

During this response, your body makes antibodies, which can help defend you against this antigen in the future. This protection your body is building is called immunity.

There are two parts to the immune system: the innate immune system and the acquired, or adaptive, immune system. You’re born with the innate immune system, and it’s active right after birth.

The innate system consists of protection offered by mucous membranes and your skin and protection offered by immune system cells and proteins. It responds the same way to all germs (24).

As you grow, your body learns things and develops acquired immunity, which comes from either a vaccine, exposure to a virus or disease, or another person’s antibodies. Acquired immunity can take over if the innate system does not destroy the germs.

The acquired immune system can remember germs, so it can specifically target the type of germ causing an infection and, hopefully, keep you from becoming ill.


The immune system is made up of cells, tissues, and organs that repel or limit infections and other diseases.

You might want to think twice before heading outdoors for a run or to a packed gym if you’re feeling under the weather.

Exercising while sick may make you feel worse or delay recovery, especially if you’re running a fever or experiencing severe symptoms (2).

It also puts others at risk of getting sick if your illness is contagious.

To decide how to proceed, you’ll need to take inventory of your symptoms.

If you’re experiencing above-the-neck symptoms like congestion, sneezing, sore throat, and runny nose, you may have the common cold and be OK to do some mild to moderate exercise (25, 26).

But if you have a fever or chills, body aches, a cough, or nausea, you could be dealing with a more serious condition, such as influenza or COVID-19 (25, 26, 27).

If that’s the case, skipping your workout is probably in your best interest.


You should listen to your body and take note of your symptoms before exercising when sick. If your symptoms are above the neck, you may be OK to work out. But if you have more severe symptoms such as a fever, rest is the best option.

Making moderate exercise a regular part of your routine contributes to your overall health and helps support your immune system.

If you’re new to exercise or have questions about how physical activity fits into your life, make sure to talk with a healthcare professional. They can help you determine the best type of exercise for you.