Tuesday, January 5, 2010

Cool Running

The Northeastern United States has been experiencing some severe weather this winter. After an early blizzard the week-end before Christmas, we’ve been treated to freezing cold temperatures accompanied by blasts of arctic winds. The combination of icy roads and sub-zero wind chills have kept me off the roads and on the hamster wheel at the gym for the past couple of weeks. I’ve made a deliberate effort to run outside as much as possible, but once the mercury drops below 20 degrees Fahrenheit, I throw in the towel. In my younger years I simply layered in more clothing and braved the elements, but then again, in my younger years I couldn’t afford a NYSC membership so I really didn’t have any other options.

All this cold weather got me thinking about the body’s response to exercising at low temperatures. I always thought that you burned more calories when working out outside in the cold, figuring that the body had to burn more calories to maintain core temperature than it does in the summertime. Surprisingly, it turns out that the reverse is true. When the ambient air temperature is hotter, your heart has to do extra work to prevent you from overheating. More than 70 percent of the energy produced by your muscles during exercise is lost as heat. The harder you exercise, the hotter your muscles become. In hot weather, not only must your heart pump extra blood to bring oxygen to your muscles, it must also pump hot blood from your heated muscles to your skin where heat can be dissipated.

On the other hand, in cold weather, your heart only has to pump blood to your muscles and very little extra blood to your skin. Your muscles produce so much heat during exercise that your body does not need to produce any additional heat to keep you warm. Curiously, this may help to explain why people find the pounds creeping on in the wintertime, even when they stay active. (Of course, it couldn’t have anything to do with elevated consumption of Christmas cookies and egg nog)

I guess running on the treadmill at the gym, (which is mercifully kept at a temperature much higher than freezing), actually helps you maintain your weight during the winter better then running outside. If only it wasn’t so terribly boring.


  1. I just loathe the treadmill not only because it's boring but also because sometimes I feel a bit nauseaous when I get off, like I'm still moving. The other aspect of running in cold weather is that I thought the blood goes to your extremities and that you lose some blood flow elsewhere, such that that was hard on the heart.

  2. Interesting. I've never heard of the heart issue. I've gotten used to the treadmill since I started working at my current job-we have several in the gym here-but I still hate it.