In the latest installment of the Cybex Research Institute’s Exercise Analysis series, we investigated calorie burn while walking, jogging, and running. And more specifically, how speed can influence calories expended while on the treadmill. If you are running on the treadmill at a fixed speed, then obviously continuing to run will burn more calories. But what if you run four miles one day at a faster speed, and four miles the next day at a slower speed – during which workout did you burn more calories? Many will tell you that the speed doesn’t matter, because you traveled the same distance during both workouts. Our research may suggest a different outcome… but why?
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Hi. Cory Hofmann here at the Cybex Research Institute with a question for you. Which would result in the greatest calorie burn: walking a mile, jogging a mile, or running a mile?
Many will tell you that there is no difference between the three because although walking is lower intensity it will take a much longer time to cover the same distance. And similarly, running is of higher intensity but performed over a much shorter period of time.
Is it really true that traveling a mile would take the same amount of fuel, regardless of speed?
The Department of Exercise Science at Syracuse University conducted an experiment attempting to answer this very question. They found that energy expenditure, another term for calorie burn, during running was 30% higher than walking when the subjects were asked to cover the same distance. But what this study failed to investigate was what would happen if we ran at different speeds. So we analyzed this subject in the lab, asking him to walk at 3 an hour, jog at 7.5 miles per hour, and run at 9.1 miles per hour for one mile, while using a device called the metabolic cart.
Specifically, this device measures the oxygen and carbon dioxide levels in the inspired and expired air of the subject during exercise. It is used in exercise physiology research and it, among other things, allows us to predict how many calories our subject burned during these activities.
Burn 30% More Calories by Running
The results from our study are consistent with past research, namely that speed does affect energy expenditure with running burning approximately 30% more calories than walking over the course of one mile, even though the walking condition took more than twice as long. The results also confirm that a moderate speed jog fell somewhere between walking and running in both duration and calorie burn.
These results make sense if you consider them within the context of the energy pathways of the human body. As the intensity of an exercise increases, we become more dependent on pathways that generate energy more quickly, but the tradeoff is that they are less efficient. Why do we care? Well, when prescribing or performing exercise, knowing the energy expenditure of certain activities is valuable - especially for those concerned with weight loss. These results show that it is valuable to run at the quickest pace that you can maintain for an extended period of time. This may be obvious to some, but even if you're not planning on entering a race anytime soon, consider incorporating some occasional sprints or other higher intensity intervals into your runs from time to time - provided of course that your body can handle the increased stresses. Not only are these intervals great for increasing speed and endurance, they can also rev up calorie burn for those looking to shed a few pounds.