Wednesday, January 30, 2013

Winter Racing: How Much Does the Cold Really Matter?

Two of my Favorite Winter Warriors!!

This past weekend, many of my running friends headed off to the Snowman Half Marathon that is part of the Winter Warriors series of races here in Michigan. These are a crazy bunch of races put on in January, February, and March, with cool names like Snowman, Ice Cube, and Mud Dogs. It is basically a chance for a bunch of crazy runners to get out of the house and stay motivated during the gloomy, frigid winter days. Besides being a lot of fun, they have some truly cute bling and age group awards, and I was very bummed to be sidelined with of all things, a tooth extraction.

Pretty cute!!

Anyway, the cold weather racing raises lots of questions for runners. The biggest ones are what to wear on one’s feet, which I mentioned in my previous post on screw shoes, and what to wear on one’s body Two layers or three? Gloves or mittens? Smartwool or Drifit or both? Balaclava or fleece beanie, or both? There are so many choices on a given day that I am almost too exhausted to actually run the race by the time I am dressed for it. Packing for all the potentials is exhausting – but I digress.

One of the key questions runners might have on race day is “how is this cold weather going to affect my race times?” I am going to put the idea of footing aside for now. I want to just focus on the idea of the effects of running in cold weather itself.

Before I ran in Michigan, I had never given much thought to how cold affects running. And, having come from a place where the coldest weather I usually had to deal with would be upper 30s maybe once or twice a year, there was really no reason to think about it.  My first race here was a 5k in about 3 degree weather. I thought I was fairly fit, but my race time was much slower than I anticipated. I was a little upset and could not figure out what was wrong. I had been training well and had done several training runs faster than my race time (and no I didn’t go out too fast).  My answer came a few weeks later when I was running with one of my new friends, Corey, in the Playmakers group. He said to me something like, “Well you know you can’t run as fast when the weather is that cold don’t you. It affects your lung and your oxygen uptake.” That was news to me. I made a mental note to look into it, but since I had no more races scheduled until warmer weather, I did not follow up. I avoided the question the following year by getting out of Michigan for the really cold winter months.

That brings me to this year where I have several races planned during what is likely to be the coldest part of the winter. I decided to look into this idea a bit further. I began by looking in some of my running books. Most of them discussed the idea of hypothermia as a hazard but did not really talk about race performance. In The Competitive Runner's Handbook by Glover and Glover, I did find a mention related to race performance. They said, “The effect of cold on performance depends on the severity of the conditions. Running in cold or moderately cold weather (30 to 50 degrees Fahrenheit) yields fast race times …. But excessive cold is another story. Exposure to extreme cold reduces both the runner’s core body temperature and maximal aerobic power, impairing performance.” They go on to say that the clothing worn also restricts movement, which can also affect race times.

Thus I found the confirmation that my friend Corey was correct (I didn’t doubt I would. Corey is one smart dude and a bad ass runner). So my next thought was “Okay, well how much does it affect it?” For that I had to turn to the Internet.

I found two really great sites that give information on this. One is an excellent article by Matt Johnson on the web site Runner’sAcademy, that discusses the key physiological components of the effects of cold on pace, including reduced muscle contractions, changes in energy sources, changes in lactate production, etc. If you are interested in understanding the physiology, the article is definitely worth a look. The bottom line is that there is a predictable performance decline in cold weather related to temperature, similar to that in hot weather:

Air Temperature
Decrease in Performance
50 °
32 °
20 °
10 °
0 °

They give an example of a person at an 8 min/mile pace to show the decline. The paces at the various temperatures would be 8:00, 8:07, 8:17, 8:26, and 8:41.

To figure out how this would play out for your particular pace, you can do the math. The formula is pretty simple:

1.  You need to convert your running pace to seconds, i.e. 9:10 pace is 9 x 60 secs +10 secs = 550 seconds.

2. Next, multiply that by the proper % from the table for the air temp at race time. For this let’s say it is 15 degrees. I will call that between 4% and 5% so 4.5% (or .045 as a decimal) 550 x .045 = 24.75 sec decrease. Let’s round it to 25 seconds.

3. Add that back to your pace per mile: 9:10 + :25 = 9:35.  So for this example, someone who would normally run a 9:10 pace could expect to run about a 9:35 pace in 15 degree weather.

If you are wondering how this would play out at other paces and are not a math whiz, I found another page with a really nice table of temperature and running performance. To take a look, click here

If you look at this table, you will see that the performance declines from 50 to 0 degrees are nearly identical to the performance declines from 50 to 100 degrees. An 8:30 runner could expect almost equal effects of temperature on performance at 100 degrees and 0 degrees. We all knew heat was a killer for running pace, but I, for one, did not know that cold could have an equal effect.

Suddenly my lackluster performance in the 5k at 3 degrees did not look so bad. I had been hoping to run around a 7:15 pace that day but had run 7:45. According to the chart, that would be just about right on.

So why is this important? Well first of all it can give you an idea of how to pace yourself on those cold days. You will not be running a PR, and to try by going out your normal 5k pace is setting yourself up for disaster and a really ugly last mile or so. Adjust your pace and expectations to fit the conditions. It also can give you the confidence to know that your training is working even if the race times aren’t showing it right now. It also can help when trying to do quality training in cold weather. Just as you would not expect to run intervals and hit a target pace in 90 degree weather, you should probably not expect to hit that pace in 10 degree weather either, even if the roads are clear.

Yes, I still hate winter, and yes, I will still avoid running in cold weather whenever possible, but when I do race in cold weather, it is good to know what to expect and how to take into account conditions. 


  1. I love the hat! I wish there were more races that gave things other than T-Shirts.

  2. Incredibly informative as always. I'll be passing this information on to my running friends. Thanks!

  3. That looks like my hat, medal and AG award. Wait, I think it is. :-) Now that I know how the temps impact my pace, how about ice, snow & yak-trax?


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