Wednesday, May 23, 2007

Running vs Walking

So recently there was a big, brewing heated debate in the Exercise Phys lab. Keep reading, as I promise this is useful!

Which burns more calories, running or walking 1mile?

Simple math, using Work=Force X Distance would say it does not matter since both of them do the same "work"? Hmmmm, that does not seem to agree with what you would intuitively think though? A quick literature search did not turn up much other than some older studies. These studies did not use more modern equipment, so they might have been off the mark a little.

Geek alert--the older studies used "Douglas bags" to collect the expired air, so when you look at the plotted data, you see distinct points (and not a whole bunch); so when you calculate the area under the curve (AUC for those researchers out there), it is not as accurate as the modern breath by breath that gives you tons of data points and therefore a more accurate AUC. Back to your regularly scheduled blog.

The solution, time to hook up some grad students and test it out!

Data back from the lab (U of MN) helped show the following

Name Calories burned rate time 3 min EPOC (kcal burned)
Subj 1 120 kcal run at 6 mph 10min 15 kcal
Subj 1 93 kcal walk at 3 mph 20 min 4 kcal

Subj 2 127 kcal run at 6 mph 10 min 15 kcal
Subj2 74 kcal walk at 3 mph 20 min 2.5 kcal

All testing was done using a Medgraphics Metabolic cart, breath by breath analysis. The distance was the same for running and walking.

Look Mom, high intensity wins again!

So by running you can burn more calories in 1/2 the time! AND you continue to burn more calories post session (EPOC--Excess Post Exercise Oxygen Consumption aka "Afterburn"). Almost 4Xs as much (about 15kcal vs 3kcal). Think of EPOC as how much you are burning AFTER the exercise to "put back what you burned". The higher the EPOC, the more calories you burn sitting on your butt! Sign me up.

The take away, if you want to burn more fat you need to do some higher intensity work!

Yes, I know this is not "stat worth" with an n=2, but see the abstracts below for more info
Nature. 1990 Jul 19;346(6281):220-1.
Energetics of bipedal running: Metabolic cost of generating force
Energy expenditure of walking and running
Computer optimization discovers walking and running