Why Running a Mile Burns More Calories Than Walking

In “Does Running Or Walking Burn More Calories?” I introduce a question my exercise physiology professor posed to my class when I was studying exercise physiology at University of Idaho. He asked: if a person runs one mile, do they burn more calories than if they had walked that one mile? Technically, the answer is no. According to physics, if all you're moving is your body weight, and you're traveling by foot, you burn the same amount of calories getting from point A to point B, no matter how fast you get there.

However, the true answer is actually more complex. And in today’s episode, you are going to learn why running a mile burns more calories than walking a mile, and how you can use this to burn more calories in your own exercise, even if you’re not a runner.

Excess Post-Exercise Oxygen Consumption (EPOC)

To understand why running burns more calories than walking that same distance, you need to know about something called excess post-exercise oxygen consumption (EPOC). When you run, you consume more oxygen than when you walk because you’re moving more muscles at greater contractions and faster paces when you run, and this means that after you finish running, your body has to pay back that oxygen “debt” by consuming more calories for several minutes or hours after you finish running. That is a "metabolic-boosting" effect that exercise scientists call excess post-exercise oxygen consumption or EPOC (incidentally, the hormonal fat-burning response to running is also greater compared to the hormonal fat-burning effect of walking). So while both walking and running burn the same amount of calories during the actual exercise, running continues to burn far more calories after you're done!

A recent study at San Diego State University entitled “Comparison of measured vs. predicted energy expenditure during 2h of work and rest” looked into exactly how much more energy you burn when you account for EPOC. The purpose of the study was to compare the predicted caloric cost of two hours of exercise and post-exercise time to the actual caloric cost of that exercise.

In the study, ten subjects performed 2 hours of exercise on a treadmill using six different work to rest cycles:

1) 3.0 mph,1.7% grade; 30 min rest, 30 min work

2) 3.5 mph, 3.8% grade; 20 min work, 40 min rest

3) 3.0 mph,1.7% grade; 30 min work, 30 min rest

4) 2.5 mph, 1% grade; 40 min work, 20 min rest

5)  2.0 mph, 1% grade; 50 min work, 10 min rest

6)  1.5 mph, 1.7% grade; 60 min work, 0 min rest

The measured calorie burn for protocols 1 and 6 were not significantly different than predicted. But for protocols 2 through 5, the measured calorie burn was significantly greater than predicted—about 7-15% higher than what would be predicted from metabolic equations found in exercise science manuals! In addition, the measured resting calorie burn was significantly higher than the predicted values by 24-46% for protocols 2 through 5.

---

The researchers concluded that: "The increased caloric cost during the resting component is believed to be due to excess post-exercise oxygen consumption. These results suggest that predictive formulas significantly underestimate the total caloric cost during work/rest exercise. Work/rest cycles utilized in an occupational setting may underestimate the total amount of work performed and result in chronic caloric deficits”.

So it turns out that if a caloric deficit is what you’re going after, the harder you push on, say, a treadmill session in which you’re moving three miles, the more calories you’ll burn long after the exercise is complete. You can check out the image below to see how much the measured versus the predicted energy changed from group to group:

How Hard Should You Work to Boost Your Metabolism?

So does this means you must always do HIIT (High Intensity Interval Training) when you exercise? Not necessarily. Another recent study entitled "EPOC Following High Intensity Aerobic Intervals and Moderate Intensity Aerobic Exercise” from the Medicine & Science in Sports & Exercise journal showed that high intensity intervals resulted in greater EPOC than moderate aerobic exercise of the same energy expenditure, but only for the first 10 minutes post exercise, which isn’t very long. This means that when  it comes to calorie burn, it’s probably more important to simply “move fast” versus always feeling as though you need to  perform interval training. In this particular study, the non HIIT group performed 30 minutes at about 50% intensity and the HIIT group performed 10x1 minute at about 90% intensity for the 1 minute efforts, with 1 minute of active rest between each effort. And again: there wasn’t a huge difference in calorie burn post-exercise between the two groups.

Ultimately the takeaway message is this: if your goal is to “boost your metabolism” and burn as many calories as possible, move fast and powerful when you exercise. Sure, there are some times when you want exercise to be relaxing, or a form of moving meditation, or an opportunity to work on sport specific skill, strength, etc., in which case “always moving fast” may not be best. But if your goal pure calorie burn, intensity is key.

Do you have more questions, comments or feedback about why running a mile burns more calories than walking a mile? Join the conversation at http://ift.tt/1PKzcip.