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How Exercise Boosts Your Immune System

Author: Forth

April 8, 2020

Reviewed by: Dr Thom Phillips

General wellbeing

Green smoothie being poured into a glass

You don’t have to be a fitness fanatic to reap the benefits of exercise. Even moderate levels of activity can be beneficial. In fact, one study found that even a brisk 30-minute walk can increase the circulation of immune cells in the body. So, whether it’s a walk in the park, a yoga class, or a game of tennis, getting moving can help to boost your immune system and keep you healthy.

The Impact of Exercise on Your Immune System

The immune system is a complex network of cells and proteins that work together to protect your body from disease and invasive microorganisms. When you exercise, your body produces more white blood cells, which are essential for fighting off infections[1]. Exercise also increases the body’s production of antibodies and boosts the activity of natural killer cells, which are responsible for hunting down and destroying cancer cells and other harmful invaders.

Studies have shown that people who exercise regularly are less likely to get sick than those who don’t[2] and regular exercise has been shown to reduce chronic inflammation, which is a risk factor for many diseases, including cancer and heart disease[3].

Another factor to consider is the time of day that you exercise. Research has shown that exercising in the morning may be more beneficial for immune function than exercising later in the day. This is because morning exercise has been shown to temporarily boost the production of cortisol, a hormone that helps regulate immune function. High and low cortisol levels over a long period of time can have a negative effect on your immune health, making exercise an essential part of your overall health.

For decades, it was thought that a session of intense exercise, such as running a marathon or an hour of powerlifting, suppressed the immune system. However, new research has shown this to be a myth. So, when it comes to deciding what exercise to do, choose what you enjoy and what aligns with your fitness goals.

How Much Exercise is Enough?

How often you should exercise will vary depending on a number of factors, including your age, your fitness level, and your overall health. However, it’s recommended that adults get at least 150 minutes of moderate-intensity exercise or 75 minutes of vigorous-intensity exercise per week[4].

But what exactly does moderate or vigorous intensity mean? Moderate-intensity exercise includes activities like brisk walking, cycling, or swimming, where you can still hold a conversation but are breathing harder than usual. Vigorous-intensity exercise, on the other hand, includes activities like running, high-intensity interval training (HIIT), or playing sports, where you are breathing hard and can only say a few words without stopping to catch your breath.

A meta-analysis of 17 studies has found that walking 4,000 steps a day can cut your risk of heart disease. The study also found that every 1,000 steps taken can reduce the all-cause mortality risk by 15%, and every 500 steps reduces your risk of heart disease by 7%[5].

6 Ways Exercise Boosts Your Immune System

Exercise is not just good for your physical health; it can also be a powerful ally in boosting your immune system. Here are six ways that exercise can help:

  1. Reduces stress hormones: When you exercise, your body releases endorphins, which are natural stress-fighters. This helps to regulate the levels of stress hormones in your body, such as cortisol, which can weaken your immune system over time if the levels are too high or low.
  2. Increases immune cell flow: Researchers found that 30-45 minutes of aerobic exercise (such as a brisk walk) increases the flow of immune cells in your body, allowing your body to detect and fight off pathogens more effectively[6]. This means that you are less likely to get sick and more able to fight off infections when you do.
  3. Boosts lymphatic system: Your lymphatic system is essential for fighting off infections, and exercise can help to improve its functioning. When you exercise, your muscles contract and relax, helping to move lymphatic fluid through your body more efficiently.
  4. Reduces chronic inflammation: Chronic inflammation can be harmful to your health and weaken your immune system. Exercise has been shown to reduce the levels of inflammation in the body, which can help to protect against chronic diseases and infections.
  5. Improves sleep quality: Getting enough quality sleep is critical for a healthy immune system. Exercise has been shown to increase sleep duration and quality[7], which can lead to improved immune health[8].
  6. Increases fitness and stamina: Regular exercise can help to increase your overall fitness and stamina, making it easier for your body to fight off illnesses and infections.

How Exercise Can Help Fight Off Infections

Exercise has been shown to improve the body’s response to vaccinations[9] and can even help those with weakened immune systems, such as cancer patients, fight off infections. Studies have found that women who exercise are less likely to develop breast cancer and there is some evidence to suggest that exercise can reduce the risk of recurrence[10].

To Exercise or Not to Exercise When You’re Sick?

It’s a common question: should you exercise when you’re feeling under the weather? The answer isn’t black and white; it depends on the severity of your illness and the type of symptoms you’re experiencing.

If you’re experiencing mild symptoms, such as a runny nose or a sore throat, it’s generally safe to continue your exercise routine at a reduced intensity. However, if you have a fever, chills, or a chest infection, it’s best to take a break until your symptoms subside. Exercise can temporarily lower your immune system, making you more susceptible to further illness, so always listen to your body.

Exercise can also have some benefits when you’re feeling under the weather. For example, a light workout can help to clear your sinuses and improve your mood. 

On the other hand, pushing yourself too hard when you’re sick can do more harm than good. It’s essential to avoid high-intensity workouts, as they can put additional stress on your body, making it harder for you to recover. Instead, focus on low-impact exercises, such as yoga or walking, which can help to keep your body moving without putting too much strain on your immune system.

It’s also important to stay hydrated when you’re sick, especially if you’re exercising. Drink plenty of water before, during, and after your workout to help flush out toxins and keep your body functioning at its best.

Finally, if you’re in doubt about whether or not to exercise, it’s best to err on the side of caution. Taking a few days off from your workout routine won’t significantly impact your fitness level, but it can help you to recover more quickly and avoid further illness.

How to Check Your Immune Health

If you’re constantly feeling unwell or get sick easily, your immune system might not be working properly. You can check your immune health with an at-home blood test. You’ll get accurate measurements on key markers that impact your immune system function, such as your red and white blood cell counts, vitamins B12 and D, ferritin (iron levels) and more.

Our immune health blood test can be done at home in less than 5 minutes and you’ll have the results within 2 working days of your sample reaching our labs. 

You can find out more on how to do a home blood test on our help page.

- Health scores calculated


This article was written by Forth

This information has been medically reviewed by Dr Thom Phillips

Thom works in NHS general practice and has a decade of experience working in both male and female elite sport. He has a background in exercise physiology and has published research into fatigue biomarkers.

Dr Thom Phillips

Dr Thom Phillips

Head of Clinical Services