Mar 022011
 

So I’ve been walking to work lately more often than riding.  I guess it’s a combination of windchill and icy roads that have kept me off my bike.

So I walk for about an hour to get to work instead of cycling for 20 minutes.  This probably burns something like 700 calories.

But now it’s -20C, which might change the caloric output required.  But which way does it change it?  A brief internet search brings up a whole bunch of conflicting information from various sources.  Ok, there are 3 opinions, the third one is that nothing changes.

Here are the basic arguments:

1) You burn less calories when exercising in the cold because your body has much less work to do in keeping you cool.  70% of the energy created when your muscles work is waste heat, and in warm weather, your heart needs to pump a lot more blood around, specifically to your skin in order to cool things down. (http://www.drmirkin.com/public/Ezine030605.html)

2) Colder weather forces the body to work harder to stay warm, so backpacking in summer might burn 3500 to 4500 calories per day, but winter backpacking can burn 4500 to more than 5000 calories per day (http://www.livestrong.com/article/292221-calories-burned-in-cold-weather/)

Wow.  Ok so apparently the world is not clear on this.  And just what is cold weather?  Perhaps some of these people are thinking about exercising in +25C weather vs +10C weather, what about -20C or -40C?

There are a lot of mechanisms at work, I suspect and there’s probably even a break-even point, where eventually your metabolism kicks up a notch to keep you warmer – I know that I’ve kicked my metabolism very hard with spending too much time at -35C (without much exercise and with insufficient clothing) and thereafter found sleeping in a house was stifling for a couple of months.  But that wasn’t exercising – I wasn’t trying to dump excess heat, I was just above shivering for many hours at a time ( at -35C in a sleeping bag rated for -15C).

Certainly, riding in snow or walking through deep snow burns more calories than walking on pavement, and one tends to wear more clothing in the winter, which could increase the weight that you transport as well as frictional losses.  That does impact me somewhat, as there are long stretches of snowy grass on my walk, my clothing, on the other hand is pretty optimal for the energy output – I would not survive the night sitting still in the clothing I walk in.  Maybe I need to wear less than enough to stay warm in order to burn extra calories.

Snowshoeing is crazy for burning calories because you can’t coast on the downhills, unlike Ronia in this possibly-too-long-shot-on-an-iPhone-while-cross-country-skiing film from last weekend at Ribbon Creek. Keep in mind she climbed all the hills to get to this point, you can hear her whooping with joy at various points:

 Posted by at 11:39 pm

  2 Responses to “It’s cold out there…”

  1. The last thirty seconds of video had blooper written all over it. 🙂

  2. I actually didn’t wipe out, despite filming what was happening behind me!