When my alarm goes off on Monday morning, it’s already 7:30 a.m., 30 minutes late.
Normally it takes me 45 minutes to walk the three kilometers to work, but this morning I ran for 20 minutes.
Yes, but by lunchtime I feel tired and like I’ve used more energy on my trip than usual, but I’ve only walked the same distance as any other day. Why does this happen?
The caloric expenditure associated with any activity is called the “metabolic cost” and is equivalent to the energy consumed by your organs to travel a certain distance.
This metabolic cost can be determined by analysing the oxygen our bodies consume and the carbon dioxide they produce, allowing us to estimate the amount of energy expended, and therefore our metabolic cost.
Using this method Researchers answered our question as early as the 1970s..
It may not be surprising, but running a given distance uses more energy than walking. But why?
Energy lost when running
Imagine watching someone running. Then look closely at the vertical movement (up and down) of their pelvis and head. As you can see in the diagram below, when they run, their body moves up and down a greater distance than when they walk.
To create this vertical movement, your lower leg muscles have to generate more force, which expends more energy but doesn’t get you any closer to your destination.
When you run, some of the energy you expend is used to move your body. Upwards, not forwardsTherefore, the energy required to run 2 miles is higher than walking.
The difference between walking and running isn’t just limited to what happens during the activity: each physical movement actually consumes delayed energy that adds to the expenditure during the activity.
Taking this into account, running still uses more energy than walking. After running 3 km, increased body temperature and replenishment of energy stores result in increased energy expenditure compared to resting, which lasts for several minutes.
This additional expense after running More than twice the value observed after walkingThis is due to the difference in intensity between the two exercises.
It’s all about speed
So, for the same distance, running burns more calories than walking, provided your walking speed is “normal” (around 5 km/h).
So if you walk very slowly, it will take you a very long time to walk 3km and you will end up burning more calories. This is because your body uses a certain amount of energy per unit of time no matter what activity you are doing (known as your “basal metabolic rate”).
The same is true if you walk very fast (Speed: 8km/h or faster): Running is more energy efficient. In this case, the adjustments required to walk at such a speed mean that you can’t take advantage of the elasticity of your tendons as you would with running, and your muscles have to be more activated.
Moreover, we have a very accurate intuitive perception of the energy efficiency of particular exercise styles: if we are on a treadmill whose speed is gradually increasing, the point at which we spontaneously switch from walking to running is The moment when walking consumes more energy than running.
In conclusion, running to work uses more energy than walking the same distance because there is greater oscillation of the centre of mass after exercise, increasing energy expenditure.
But remember, whether you choose to walk or run to work, the most important thing is that you’re already saving energy.
Crémant ReminurPhD in Human Movement Science, University of the Cote d’Azur; Clement NaveyanPhD in Human Movement Science, University of the Cote d’Azurand Francois DelnoncourtPhD in Human Movement Science, University of the Cote d’Azur
This article is reprinted from conversation Published under a Creative Commons license. Original Article.
