Science Says: Exercise Boosts Immune System and Keeps Muscles Young

Molly Hurford
by Molly Hurford
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Science Says: Exercise Boosts Immune System and Keeps Muscles Young

Exercise doesn’t just help you live longer, it helps you live better — and the benefits extend further than you might think. A new piece of research published in Aging Cell looked at cyclists ranging from 55–79 years old and assessed their immune function. Dr. Janet Lord, the Director of the Institute of Inflammation and Ageing at the University of Birmingham, has been focusing on exercise and its impacts on immunity for years and says the best thing we can do to stay healthy longer is exercise.

Studies show that if you exercise as you get older, your muscles will stay strong and intact longer, while your blood pressure may avoid the uptick often associated with aging. But even more, your immune system receives a serious boost from regular exercise, making your ability to fight infection and disease at the age of 80 the same as someone half, or even a quarter, of your age.


A keen runner herself, Lord considered using runners in the initial study, but cycling was an easier sport to track as the riders tended to be less prone to injury and “most cyclists keep good records, so we could verify that they were doing as much as they said,” Lord explains. “Plus, cyclists ride all year round, while swimmers, for example, have a longer offseason.”

The cyclists in the study were amateur, recreational riders, though they averaged 150–200 kilometers each week while working normal jobs or enjoying retirement. “They aren’t Olympians or former professionals, though,” Lord is quick to note. “Just normal people who go for long rides on the weekend and ride at a pretty good pace.”

The study began in 2014 and tracked other markers of aging, but the most recent focus was analyzing the immune response to exercise, and the results shocked even Lord, a seasoned immunologist. “We weren’t designed to be sedentary, we weren’t designed to eat whatever we liked as hunter-gatherers. And our research into the physiology of aging cyclists showed that they weren’t losing muscle, they didn’t increase their blood pressure, they really were in a great state,” Lord said. “The second paper said that you might not be surprised that you won’t lose muscle if you keep exercising, but what about looking at a system that doesn’t seem as connected to exercise?”


That system — the immune system — was the next focus for the team, and the team’s finding countered the widespread belief that as a person ages, the thymus, the area responsible for the hormones that control the immune system, starts shrinking. But with these cyclists, that simply didn’t happen. “The cyclists had the same amount of new immune cells as a 20-year-old, so with exercise, the thymus doesn’t shrink at all.”

Lord posits that the reason for this is that those new immune cells are created by muscles, so an aging runner or cyclist who’s maintaining muscle with regular exercise is making lots of the immune hormone that keeps the thymus working optimally.

“You can delay or reverse aging through exercise.”


Before you start panicking that you haven’t been a lifelong runner, don’t stress: Lord says many of the athletes in the study actually hadn’t picked up cycling until their late 30s or even into their 40s, and there wasn’t a difference between those latecomers and those who’d been training since their teen years.


“We don’t know how late you can take it up to get the effects,” she admits, “But there wasn’t any correlation that we were able to find. As long as you do a good level of exercise at any age, we think you should be able to get the benefits. No excuses!”

The main message Lord is hoping to get across is simple: “You can delay or reverse aging through exercise.”

Why aren’t more people doing this, if it’s so obvious? “In 400 B.C., Hippocrates said that exercise was the best medicine … But it’s the one people are least likely to take,” she adds. “Only 5% of people over 65 are active enough. It’s scary. In the U.S., people are most physically active at 6 years old. As soon as kids go to school, they stop physical activity.”

Support your immune system with a well-balanced diet to help your body function at its best. Go to “Plans” in the MyFitnessPal app to try our 14-day Support Your Immune System plan.

About the Author

Molly Hurford
Molly Hurford

Molly is an outdoor adventurer and professional nomad obsessed with all things running, nutrition, cycling and movement-related. When not outside, she’s writing and podcasting about being outside, training and health. You can follow along with her adventures on Instagram at @mollyjhurford.


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