What Is cardio aka running or walking?
You know you should do it. You know it can be a boon to health. You know it involves sweating. But beyond that — what is cardio exercise exactly? How does it affect the body differently from other forms of exercise? What counts as cardio training and what doesn’t? How often should you do it, and how should you do it? We have the answers below.
What Is Cardio Training?
“People tend to think of cardio in terms of steady-state exercise, like jogging,” says Trevor Thieme, C.S.C.S. and Openfit’s senior manager of fitness and nutrition content. “But really, cardio is anything that A) raises your heart and breathing rates, and B) improves the function of your heart, lungs, and circulatory system.”
To bring more clarity to this type of exercise, let’s tackle a few common cardio training misconceptions one at a time:
Walking is an easy way to get some exercise in your day, and it delivers mental health benefits as well. I’m one of the many people who added daily walks to my routine during the pandemic, and they improved my life so much I don’t intend to stop. But does walking do enough for your body that you can count it as cardio exercise?
The answer is complicated. Walking counts as cardio in some respects: it can burn calories, it gets your heart rate up, and it counts toward the exercise we should all be getting every week. But on the other hand, it’s not going to increase your cardio fitness in the same way as a run or an intense aerobics class would. If you want to improve your endurance, you’ll have to do more than just walking.
How walking’s calorie burn compares to running
Running burns more calories than walking per unit time, but both are similar when you consider distance.
A rule of thumb is that you burn about 100 calories per mile whether you run it or walk it, but in truth, calorie burn varies according to the size of your body (you burn more calories if you are larger) and how fast you run or walk. The calories per mile are slightly lower when you walk. This calculator from Runtastic (in metric, sorry) estimates that a 150-pound person will burn 82 calories by walking a mile, or 115 calories by running it.
The biggest difference is in calories per hour: for the same 150-pound person, walking burns 261 calories per hour, and running burns 714. For both calculations, I used the examples of a 20-minute mile (3 mph) for the walker and a 10-minute mile (6 mph) for the runner. The faster you go, the higher the calorie burn.
So if you’re walking or running to burn calories, running will burn more calories in half the time. But if you prefer walking and you have the time to spare, both will do the job.
The walking can’t replace “vigorous” cardio
Each intensity level of exercise offers its own benefits. Walking is what I’d consider very easy cardio, jogging is more of a medium exercise, and high-intensity cardio would be something like sprinting or racing. All of these are good for you, although depending on your goals, you may not need to do all of them.
If you want to be a fast runner, for example, you’ll need plenty of medium cardio (slow running) and some higher intensity stuff (speedwork); if you want to improve your endurance, as measured by metrics like VO2max, you’ll definitely need to put in some work at these intensities.
On the other hand, if you’re just trying to get some movement in your life and you don’t care about getting better at it, lower intensity exercise like walking may be enough.
According to major health organizations (including the CDC, the WHO, and the AHA), we should all be getting at least 150 minutes per week of “moderate” exercise, or 75 minutes of “vigorous” exercise. You can mix and match, with the idea that each minute of vigorous exercise counts double.
So where does walking fall in that recommendation? Well, the American Heart Association defines moderate exercise as that in which your heart rate is between 50-70% of your max and vigorous exercise as between 70-85% of your max. Walking will generally be in the moderate range, so you’ll have to do twice as much of it—counting in minutes—as if you chose to do more vigorous cardio.
Walking doesn’t have to mean an easy stroll
The distinction between walking and running is a mechanical one: if you always have at least one foot on the ground, you’re walking. If instead, your gait has a little hop as you move from foot to foot, you’re running. (Jogging is simply a slow run.)
It’s often easier to keep up a higher intensity (and a higher heart rate) by running than by walking, but that’s not always true. If you’re hiking up a mountain, your heart rate can easily get into the “vigorous” zone. And if you’re an efficient enough runner, you may be able to go for a slow jog while you keep your heart rate down in the “moderate” realm.
As you’re planning your workouts, think about the intensity: Measure your heart rate if you aren’t sure where you fall; you can use a tracker like a Fitbit or an Apple Watch to do this, but you can also just put two fingers on the side of your neck and count the beats of your pulse. If your max is 200 and you count 150 beats per minute, you’re at 75% of your max heart rate.
Maybe walking gets you a higher heart rate than you thought—not impossible if you’re a beginner or if your walks take you over hilly terrain. If you want a tougher cardio workout, you can walk faster, or you can choose a different type of exercise like cycling or dancing that gets your heart rate up higher. But it’s fine to go for an easy walk if that’s all you’re aiming for.