Exercising can boost your immune system, particularly when combined with adequate stress management, sleep habits, and a balanced diet. The simple act of moving your body more can provide a powerful tool for fighting infection. The catch? Not all exercise offers the same boost to your immune system.

1. Increases Blood and Lymph Flow

In addition to improving your mental health, a 2019 scientific review found that exercise can improve your immune response, lower illness risk, and reduce inflammation.

Because exercise increases blood and lymph flow as your muscles contract, it also increases the circulation of immune cells, making them roam the body at a higher rate and in higher numbers, David Nieman, DrPH, the study author and a professor in the department of biology at Appalachian State University and director of the university’s Human Performance Laboratory, told Health.

Specifically, exercise helps to recruit highly specialized immune cells, such as natural killer cells and T cells, find pathogens (like viruses) and wipe them out. Research shows that participants who took a 45-minute brisk walk experienced this uptick of immune cells floating around the body for up to three hours after the walk.

2. Improves Immune Response

While you get an immediate response from your immune system when you exercise, that will eventually go away—unless, that is, you work out consistently. “If you go out for 45 minutes of exercise the next day, this all happens again,” said Dr. Nieman. “It all adds up as time goes on.”

Another earlier study by Dr. Nieman and his team found that those who did aerobic exercise five or more days a week lowered the number of upper respiratory tract infections (like the common cold) over 12 weeks by more than 40%.

In 2022, researchers looked at 16 studies of people who stayed physically active during the pandemic. They found that exercise was associated with a lower risk of infection and a lower likelihood of severe COVID-19. People from around the world who worked out regularly had a 36% lower risk of hospitalization and a 43% lower risk of death from COVID than those who were not active.

“Exercise really is a housekeeping activity, where it helps the immune system patrol the body and detect and evade bacteria and viruses,” said Dr. Nieman. So, you can’t necessarily exercise one day here and there and expect to have an illness-clearing immune system. With regular physical activity, your immune system is better prepared to wipe out sickness-causing germs.

This benefit holds up even as you get older.

3. Decreases Inflammation

Another benefit of exercise is that it decreases inflammation in the body. This, in turn, can also improve immunity as reduced inflammation enhances immune function because your cells can work better and fight infection more efficiently.

According to Dr. Nieman, decreased inflammation goes hand-in-hand with immunity. “When immune cells try to function with inflammation, it puts the immune system in a chronically inflamed state too,” said Dr. Nieman, which makes it harder to fight infection.

Exercises That May Boost Your Immune System

There’s limited research on the best type of exercise to boost immunity. Most studies, including Dr. Nieman’s, looked at aerobic activity—think walking, running, or cycling.

Walking

It’s best to push the pace a bit to gain the benefits of walking. “For most people, we’re talking about a 15-minute mile,” said Dr. Neiman of the average pace that led to promising results in his studies. “That’s sufficient stimulus to recruit immune cells into circulation.” For other forms of exercise, aim to reach about 70% of your max heart rate, suggested Dr. Nieman.

HIIT Workouts

There’s less science on whether high-intensity interval training workouts (or HIIT, a popular type of exercise) help your immunity. One study from 2018, which focused on arthritis patients, found that HIIT could improve immune function. Other research found that HIIT workouts don’t lower immunity.

In general, interval workouts are likely OK. “Our bodies are used to this back-and-forth nature, even for a few hours, as long as it’s not unrelenting high-intensity exercise,” said Dr. Neiman.

Strength Training

The same goes for strength training—it likely helps your immune system, but there’s less research backing up its benefits on immunity. Adam Jajtner, Ph.D., CSCS, assistant professor of exercise science and physiology at Kent State University, who has also studied exercise and the immune response, told Health that resistance training is a smart strategy for improving immunity.

However, Dr. Jajtner cautioned against severe muscle-damaging workouts, like lifting super heavy or doing eccentric exercises (slowing down the downward phase of a movement) so that the muscle repair process doesn’t compete with your immune function. Instead, try a light to moderate strength routine.

Tips

Aim for a regular schedule of exercise each week. Consistency will offer the biggest benefits. The Centers for Disease Control and Prevention recommends about 30 minutes of physical activity most days, including cardiovascular activities like walking or swimming and strength training.

If you’re new to exercise (and have your healthcare provider’s approval to start a fitness program), walking is a great way to ease into more physical activity. Dr. Jajtner suggested going out for even 10 minutes two to four times a day. Then, work on gradually increasing that time.

Can Exercise Harm Your Immune System?

Research indicates that excessive exercise may be harmful to your immune system. Pushing yourself too hard for too long can put you at higher risk of infection—but you have to go pretty far past that “acute” level of training to experience adverse side effects.

This negative effect could come into play if you’re running at a high intensity for at least a half-marathon distance or cycling or swimming at a challenging pace for about 90 minutes. Any of these longer, more intense activities can cause stress on the body, which could lead to lowered immune function.

In a 2021 review study, researchers looked at potential health problems experienced with ultra-endurance running (UER). The researchers found that, following UER, there is a transient immunosuppression for several hours, which could increase the risk of viral and bacterial infections.

How long and hard you can push yourself before you reach that excessive and intense level of exercise ultimately comes down to how well you’re trained. Still, you might want to focus on maintenance rather than intensity to enhance your immune system.

A Quick Review

While other lifestyle habits like eating fruit, managing stress, and getting quality sleep can also help reduce your risk of illness, exercise is another effective way to boost your immune system. People who work out regularly experience fewer infections, as long as they don’t push themselves too hard.

You’ll get the biggest boost to your health by keeping a regular exercise routine. Aerobic workouts like running and cycling are excellent immune boosters. Contact a healthcare provider for suggestions on the best workout routine and strategies for your health.