Wednesday, September 12, 2012

Night Run

So after a long day of getting almost everything done except the million and one things that I really needed to get done, I rushed home from the office (ok, not technically "my" office - the surveyor's office) and got home just in time to miss out on the housework (oops) and catch the tail end of a paltry dinner (frozen pizza) and rush back out the door to take my daughter to Brownies where I got conned into taking on a FOUR-badge booklet on the Wonders of Water (in OneHourIronman language - my "bailiwick" so I guess all will be ok).

But also while at Brownies, Stacy called and I reluctantly agreed to go for a jog at 8:30 - this being the only time she ever seems to break away from her own household/mom duties to go.  Put on my neon/reflective shirt and away we went into the night.  Mostly on sidewalk and in my relatively quiet neighborhood for a little over 3 miles (same as Sunday). 

We got to talking and I am curious - weigh in all you nerdy number people.  Do you think you burn the same total calories (energy) to cover 3 miles regardless if you are running or walking.  Now I realize that if you are a speed demon - you might do this in 20 min and if you are a slow ass walker it might take you 45-50 min.  But in the end, aren't you moving your mass (a constant for this scenario) from one point to another (distance constant again) - so shouldn't the work to accomplish this be equal if you don't regard the time it takes?  So I plugged it into my Sparkpeople app and it turns out that no - going three miles at 10 min/mile (trust me this would be my all out run pace) should burn around 372 cal vs. three miles walking at 15 min/mile would burn around 251 calories (this may be using the stats I gave it for my age, weight and sex to figure so just go with me on the numbers).  The first scenario would take 30 min and one would take 45 min.  My theory is that it shouldn't matter, but then I pulled my really geek move and looked into my Physics book for the definition of "work"= Force x distance; and we all know that F=ma (Force = mass x acceleration).  But my mass stayed constant and my distance is constant - so it must be in the acceleration (though in my examples I assume a "constant velocity" in each scenario so is my a = g (acceleration due to gravity))?

My husband thinks this is why I should NOT spend the money on a fancy Garmin sports watch.  He thinks the engiNERD brain wouldn't be able to contain itself with all that data to analyze.  I mean, look at the tangent I can end up on over a simple 3 mi walk/jog.  Anyone think my husband is right? 

Tomorrow I'm off to do some field work (surveying should always be done when it is supposed to be nice out).  Probably take another couple of workout rest days so I'm ready to do the Prison Break on Saturday!  Gotta hit the showers!  Good night!


  1. I definitely think you should get the garmin. As an engineer myself, I love the data. If your mass and distance is constant then acceleration is the only other variable that is changing (which is true). I think the running will give a bit more calorie burn over the same distance as walking because there are much greater vertical moments fighting gravity when jogging/running. That, in turn, requires more blood flow to the muscles causing a higher heart rate. More oxygen is required which contributes to calorie burn. Of course, I could be way off on that, but it was fun thinking about it. Ok, enough nerd stuff... just run.

  2. NIce run! I have no input on the whole running vs. walking calorie thing because the question made my head hurt. :) I love/hate my Garmin for the heavy dose of reality it gives me re: my pace at times, but I know there's mounds more I could do with the data I get. Someday...

    See you Saturday!

  3. I always used to think you burned the same calories per distance too, but all the online calculators think differently.

    I love my garmin though...

  4. I love that you did a full on physics equation on this! :)

    I love our Garmin, but I find that I get too obsessed with numbers when I use it. So I don't. And I'm much happier. :)