Does Intense Exercise Temporarily Suppress Your Immune System?


High intensity exercise and immune health


You may have heard that high-intensity workouts place enough stress on your body to suppress the immune system for several hours afterward. We depend on a healthy immune system to protect us against viruses and even tumor cells. Your immune system is trained to identify such foreign invaders and act with precision and in a timely manner. So, you might be concerned that your body can’t fight off outside forces after an intense workout. Is there any truth to the idea that intense workouts suppress immunity?

A study carried out by researchers at the University of Bath has reassuring news if you’re concerned about intense exercise suppressing immunity. They discovered that the immune cell changes that take place after an intense workout may actually be beneficial. Their research shows that during endurance exercise, the number of infection-fighting immune cells that enter the bloodstream increase by up to 10-fold. However, during the recovery phase after exercise, the numbers decline, often to where there are fewer than before the exercise session. The reduced number of immune cells may persist for hours after a workout is over.

Should you be alarmed by the drop in immune cells in your bloodstream? Quite the contrary!  The researchers discovered that the drop in immune cells in the bloodstream is because the cells travel to other sites such as the lungs and nasal passages where they’re more available to fight infection. The way they showed this is by labeling immune cells with tags so they could see where they go. The immune cells are traveling to sites where they can better protect you against infection.

Therefore, the drop in immune cells in the bloodstream isn’t a drawback but a positive for your health and resistance to infection. Although you may have fewer immune cells circulating in your bloodstream your immune system may be even more capable of performing its job because it sends immune cells to sites where they can more actively survey the environment for invaders and react quickly.

Exercise May Slow Immune System Aging

Your immune system ages like every other organ in the human body. Some types of immune cells decrease with aging, but others, like neutrophils and natural killer cells, increase in number, although they became less efficient and accurate at performing their duties. On the plus side, research suggests that regular exercise may delay or reduce the extent to which the immune system ages. Many people exercise for the anti-aging benefits it offers, not realizing exercise also slows immune system aging.

Research shows older people are more likely to die from infection than younger adults due to a less robust immune system. Elderly adults also have a less pronounced response to vaccinations, including the influenza vaccine. That’s why there’s a more potent influenza vaccine for adults ages 65 and older. The good news? Research shows that exercise may enhance an older person’s immune response to vaccines. Therefore, exercise, if anything, boosts the body’s defenses against infection.

Other Ways Exercise Benefits Immune Health

One type of immune cell called T-cells are helpful for fighting viruses. When you’re exposed to viruses, T-cells that fight that virus increase in number and remain in your tissues. When too many T-cell clones build-up, it can be a problem since they crowd out younger immune cells. Exercise seems to help here too. Physical activity helps rid the body of old T-cell clones that take up space and crowd out the healthier cells.

Exercise has other benefits for immune health. When you do a workout that boosts your heart rate, circulation increases, and immune cells can circulate through your body more easily and reach destinations where they can better fight infection.

Prime Your Immune System with a Healthy Lifestyle

Other lifestyle factors also impact how robustly your immune system reacts. One of the biggest of these is sleep. Most adults need between 7 and 8 hours of sleep each night, but not everyone gets that amount. Even people who try to get that quantity of sleep may fall short because of problems falling or staying asleep. Studies show that when people sleep too little, immune cells called T-cell decrease in number and chemicals called cytokines that produce inflammation go up. This makes it harder for you to fight off infections, including cold and flu viruses.

As mentioned, people who exercise have a better response to the seasonal flu vaccine, but studies also show subjects who sleep too little mount less of a protective immune response to the seasonal flu vaccine. So, the vaccine may be less effective in those who are sleep deprived.

What about the impact of stress on the immune system? Physical and mental stress boosts the stress hormone cortisol, and that suppresses immunity against infection. That’s why it’s important to have ways to manage stress, whether it be meditation, yoga, a walk outdoors, or spending time with a pet or talking to close friends. We live in a stressful world! Make stress management a priority.

Don’t forget about nutrition either. Make sure you’re consuming enough calories and eating nutrient-dense foods. Vitamins C, E, and D and the minerals zinc and selenium play a key role in immune health. Make sure you’re eating plenty of fruits and vegetables rich in antioxidants too.

The Bottom Line

Strenuous exercise may not suppress your immune system for a few hours afterward after all. In reality, it may only shift immune cells to more strategic locations and give you better defense against pathogens like viruses. Plus, exercise may slow aging of the immune system by reducing clones of old immune cells that crowd out younger ones. However, excessive amounts of exercise without adequate recovery increases cortisol and that suppresses immune function. So, make sure you’re giving your body enough downtime too.



  • org. “Research debunks ‘myth’ that strenuous exercise suppresses the immune system”
  • Front Immunol. 2018; 9: 648.Published online 2018 Apr 16. doi: 10.3389/fimmu.2018.00648.
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  • Exerc Sport Sci Rev. 2011 Jan;39(1):23-33. doi: 10.1097/JES.0b013e318201f39d.
  • Harvard Health Publishing. “How to boost your immune system”
  • org. “How Sleep Affects Your Immunity”
  • com. “Can Better Sleep Mean Catching Fewer Colds?”


Related Articles:

5 Science-Backed Ways to Improve Immune Health if You Work Out

What Are the Short and Long-Term Effects of Exercise on the Immune System?

What Impact Does Exercise Have on Your Immune System?

Can Exercise Slow Immune System Aging?

What Happens to Your Immune System as You Age?

How Your Immune System Ages and Why It Matters

6 Keys to a Healthy Immune System

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