If you want to support a healthy immune system, you’d be hard pressed to find a better activity than exercise. “When a person exercises, chemicals are produced that improve immune function,” says Carissa Smock, PhD, MPH, Associate Professor of Health Services at Northcentral University and Chair of the American Public Health Association’s Physical Activity Section. “This is caused by changes in antibodies and white blood cells as they circulate faster during exercise as well as the rise in body temperature.”
“Exercise increases blood and lymph flow and helps circulate the white blood cells—cells that fight off infection,” says board-certified internist and women’s health specialist Dr. Soma Mandal. “Exercise also decreases inflammation, which can improve the immune system.”
Exercise can also help you get more (and better quality) sleep—which also plays a large role in immune function. “Regular exercise also helps improve sleep quality—and sleep is crucial to our immune system,” says Tiffany Allen, FNP-C, WHNP-BC, nurse practitioner and founder of Triad Lifestyle Medicine. “While we are sleeping, our immune system releases cytokines which increase with infection to help fight illness. If deprived of sleep, it may decrease production of the protective cytokines which would decrease our body’s ability to fight off infection.”
But if you want to get the most benefit out of your fitness routine? Take your workout outside.
Exercising outdoors has additional immune-supporting benefits you won’t get when working out inside. But what, exactly, are those benefits? How can working out outside support healthy immune function? And what are some ways you can optimize your outdoor workouts for maximum immune-supporting benefit?
Exercising outdoors gives you more sun exposure
Vitamin D plays a major role in your body’s immune function. “Vitamin D aids in decreasing inflammation and supports the performance of the white blood cells that aid in our body’s ability to fight off pathogens and infections,” says Allen.
And, on the flip side, vitamin D deficiency can wreak havoc on your immune system. “Low levels of vitamin D have been shown to increase susceptibility to infection—and Vitamin D deficiency is commonly found in those with autoimmune conditions,” says Allen.
Luckily, there’s a great way to get the vitamin D (also known as the “sunshine vitamin”) you need to support healthy immune function. Taking your workout outside gives you exposure to the sun—and “regular sun exposure is the most natural way for your own body to manufacture vitamin D,” says Mandal.
Bottom line? Your immune system needs vitamin D to function properly—and exercising outside is a great way to get the vitamin D you need to support a healthy immune system.
Exercising outdoors lowers stress
When you’re stressed out, your body produces cortisol (also known as the “stress hormone”)—and cortisol does not do good things for your immune system. “Chronically elevated cortisol levels (think stress) can increase inflammation and work against the immune system,” says Mandal.
If you want to support healthy immune function, you need to kick stress to the curb and get cortisol levels under control, and taking your workouts outside is a great way to do it.
Spending time outdoors has been shown to lower heart rate and blood pressure and improve mood, all of which play into regulating stress. Getting outside also decreases cortisol levels in the body; a recent study found that spending just 20 to 30 minutes outside can decrease cortisol levels by an impressive 21 percent per hour.
So, if you want to destress, lower cortisol levels, and support your immune system, instead of hitting the gym? Try taking your fitness routine outside.*
Tips for getting the most immune-supporting benefits out of your outdoor fitness routine
Want to reap the most immune-supporting benefits from your outdoor fitness routine? Make sure to follow these tips:
Get your cardio on. As mentioned, exercise in general is great for supporting your immune system—but cardio is particularly beneficial. “Any type of cardiovascular aerobic exercise can help improve the immune system,” says Mandal. Next time you head outdoors to exercise, aim to get your heart rate up—for example, by lacing up your shoes for a run or hitting the trails for a vigorous hike. Use the Exercise app on your Fitbit device to track your core stats while working out, like heart rate, distance, calories burned, and Active Zone Minutes.
Get enough sun exposure. As mentioned, exercising outdoors in the sun helps you get enough vitamin D, which plays a major role in healthy immune function—that is, as long as your workouts are long enough. “The amount of time it takes to absorb the Vitamin D needed to support healthy immune function depends on the time of day, time of year, amount of skin exposed, and natural skin pigment,” says Smock.
Smock recommends people with a lighter skin tone aim to get out in the sun for at least 10 to 15 minutes at midday (with arms and legs exposed) a few times a week. If you have a darker skin tone, you’re getting outside earlier or later in the day, or you’re wearing pants and/or a long-sleeved shirt, you’ll need more time in the sun.
Get outside, even if you can’t work out. If you want to support healthy immune function, exercising outside is ideal. But if, for whatever reason, you can’t work out, there are still benefits to getting outdoors—and you should still try to spend time outside. “It should be noted, that while being active outdoors is highly beneficial, stress reduction and vitamin absorption—and therefore increased immune system function—can occur by simply being outside,” says Smock.
* Want more ways to understand your stress? Try using the Stress Management Score on your Fitbit Sense. You can see a daily Stress Management Score in the Fitbit app ranging from 1 to 100—where a higher number means you’re showing fewer physical signs of stress.
This information is for educational purposes only and is not intended as a substitute for medical diagnosis or treatment. You should not use this information to diagnose or treat a health problem or condition. Always check with your doctor before changing your diet, altering your sleep habits, taking supplements, or starting a new fitness routine.