When you head out on a walk, thousands of things are happening in your body, from the muscles in your legs (and core and arms) to your brain, your gut, and your immune and endocrine systems. Here, we’re looking at what happens to your body throughout a walk, with insight from former professional triathlete and current researcher Alexandra Coates. Coates now spends much of her day in the lab looking at exactly how exercise affects our bodies (and how much we can and should be doing).
Funny enough, before you even head out the door, your body might boost your heart rate simply by thinking of walking. “Because your body knows it’s about to exercise, you’ll often have this increase in heart rate before you even start, and your hormones like epinephrine and norepinephrine start to increase,” explains Coates.
Imagine your body is lighting a match during the first minute and a half of your walk. “Right at the outset of your walk, you’re going to have to start up your aerobic metabolism a little bit, which means your anaerobic metabolism is switching on briefly,” explains Coates.
By 90 seconds, your aerobic system has kicked in. For the rest of your walk, your body will primarily be burning fat for fuel, with minimal support from carbohydrates via your muscle glycogen stores.
“So long as you’re keeping it easy, you’re basically just burning fat with a tiny bit of glycogen,” says Coates. “To burn through your glycogen stores completely, you’d have to walk at that intensity for over three hours — and probably closer to four hours.”
She adds you shouldn’t drop your speed from running to walking just to get the fat-burning benefits. At faster paces, you burn more carbohydrates in the form of glycogen, but you’re also burning fat and calories at a higher rate, so speeding up is still important for overall caloric burn.
At the 2-minute mark, you’ve offset sitting at a desk for an hour. A 2015 study showed simply walking for two minutes every hour can actually undo most of the harmful effects of sitting at your desk. (You’ll have to do these short walks multiple times each day though, so don’t think you’re in the clear just because you walked from your car to your desk at the office!)
By 5 minutes, you’ve helped reset your circadian rhythm. “Getting outside and having the sun hit your eyes is so good for getting better sleep, as well as for overall health and happiness,” says Coates. “And it doesn’t take a huge dose before it becomes effective for improving our moods.”
CLICK TO TWEET THIS ARTICLE > Here are all the benefits of a walk, broken down minute-by-minute. (via @myfitnesspal)
Ten minutes into your walk, you begin to increase stress — in a good way. It may seem counterintuitive, but when you exercise, you actually increase your stress and cortisol levels. Ultimately, however, this benefits our bodies.
“When you walk, you’re increasing your stress response, and you are also increasing inflammation,” explains Coates. “But as soon as you’re done, it’s actually anti-inflammatory because your body releases that cortisol in order to stop the inflammation. So the overall effect is a reduced-stress, anti-inflammatory environment even after a short walk.”
After a 15-minute walk, you’re less likely to indulge in a sweet treat. Walking for this time period was shown to curb cravings for chocolate in a study conducted by Exeter University, and Coates notes that because walking is such a low-intensity activity, you can walk for quite a while before you’d feel the urge or need for a post-workout meal.
By 20 minutes, you’ve boosted your immune function. A study that surveyed 1,000 men and women found those who walked 20 minutes a day had 43％ fewer sick days than their sedentary counterparts, and if they did get sick, their symptoms were milder. “It’s amazing what getting outside and moving can do for your mood, and for your immune system,” says Coates.
Going out for a walk in nature not only helps your body, it also helps your mood. After 20 minutes, your brain begins to de-stress, and for optimal cortisol-reduction, 30 minutes is the time researchers found provided the most relief from a tough day. (Walking 30 minutes five days a week at a vigorous pace also helps you hit the recommended Physical Activity Guidelines from the Department of Health and Human Services!)
If you’re hoping to lose weight or stave off diabetes, a 60-minute walk might be the ticket. A study from Harvard found a daily hour-long brisk walk cut the effects of obesity-promoting genes in half. “If you are diabetic and you have insulin resistance, your insulin doesn’t work properly,” says Coates. “But with activities like walking, you can get your blood glucose under control.”
THE BOTTOM LINE
You don’t have to walk for an hour to benefit from the workout, but the longer you walk, the more benefits you could see. Take it slow and easy, stick with what works for you and you’re sure to see positive results across your mental, physical and emotional health.
Make progress every day while you work on fitness and nutrition goals, like walking more steps. Go to “Plans” in the MyFitnessPal app for daily coaching and easy-to-follow tasks to keep you motivated.