Guest blog by John Davis (RunnersConnect)

With autumn already upon us, many runners are looking ahead to their final races of the year. While there’s usually a lull in road races in the late fall and early winter, there are nevertheless many races near Halloween, Thanksgiving, Christmas, and New Year’s Day with good competition and maybe even some holiday-themed prizes.

When racing and working out at this time of year, the temperature is a concern for runners in many parts of the country. Not only do many runners think running in the cold is bad for you, but it’s not an appealing thought to be standing on the starting line shivering in your spandex.

This week, we’ll look at the effects of cold temperatures on performance. While it’s well-known that performance is impaired when it’s too hot, it’s also likely that performance will be impaired if it’s too cold.

The research on running in the cold

First, we’ll have to take a look at the scientific literature to see what happens to your body when it exercises in the cold. As is often the case with environmental factors, the military has taken a keen interest in the physiology of exercise in the cold.

This was the topic of a 1991 review by Thomas Doubt at the Naval Medical Research Institute. In this article, Doubt lists a number of changes that occur during exercise in low-temperature settings:

• Your body relies more heavily on carbohydrates and less on fats for its energy

• Your lactate production is higher for a given intensity, indicating that you’re going deeper into “oxygen debt” to produce the necessary energy to maintain a given pace (as evidenced by a higher oxygen consumption rate in colder temperatures)

• Your muscle contractions are less powerful, which demands an increase in fast-twitch muscle fiber usage, perhaps explaining the higher lactate production

All of these adaptations have consequences for running: relying more strongly on carbohydrates will drain your energy reserves faster on long runs, and could spell trouble in a winter marathon. Higher lactate production and less efficient muscle contractions are also problematic for shorter races.

Fortunately, Doubt points out that these effects can be mitigated by maintaining your body and muscle temperature with warm clothing and moderate activity (like jogging). However, short to medium-length bouts of high-intensity don’t seem to boost body or muscle temperatures, so once you’ve cooled off, you won’t be able to warm back up during a race or workout!

Performance drop of running in cold weather

Reviewing more recent literature in a 2006 article, Lawrence Armstrong at the University of Connecticut points out that some of the performance drops associated with cold weather may be the result of having a higher baseline metabolic rate, which is one of the body’s mechanisms to maintain core temperature.

Shivering is a good example of this, though your metabolic rate is higher in the cold even when you’re not shivering. Armstrong suggests this could “steal” energy that would otherwise be used for athletic performance.

Moreover, Armstrong cites several studies which demonstrate that dehydration is a risk in cold weather, as low temperatures increase urine output and diminish thirst. Water losses from breathing and sweating remain significant, even in cold temperatures, so staying hydrated should be a priority.

How the body adapts to running in the cold

Finally, a 2004 review by Myra Nimmo at the University of Strathclyde in the UK looked at how the body’s adaptations to cold vary based on the temperature outside.

Nimmo rehashed many of the findings of Armstrong and Doubt: in the cold, your body burns more carbohydrates, less fat, and has higher oxygen consumption at a given exercise intensity.

Explosive power is also limited by the temperature of the muscles (which, Nimmo points out, can differ significantly from the body’s core temperature).

But furthermore, Nimmo found that these physiological changes become more drastic as your core temperature drops. Hence, it’s critically important from a performance standpoint to keep your body warm when exercising in the cold.

She also points out that, while many of the military and athletic studies are done on “athletes” in general, endurance athletes in particular are especially vulnerable to performance deficits from cold temperatures due to their slim build. Environments that are cold and wet are also problematic, as they dramatically increase heat loss and render many fabrics ineffective.

According to Nimmo, the ideal temperature for endurance exercise is somewhere around 52 degrees Fahrenheit.

Final thoughts on running in the cold

From all of these studies, we can conclude that running in the cold can impact performance. Luckily, our look into the research also revealed some helpful tips.

• It’s quite important to stay warm before and during a workout or a race in the cold. And, as Doubt points out, it’s important to maintain your body temperature, as it’s much harder to bring it back up once it has dropped. Warming up before a race or workout becomes even more critical in the cold.

• Minding your carbohydrate and fluid intake is also important, as you’re more likely to “hit the wall” in training or in a long race during cold weather, and dehydration is a risk too. Here is some research on the science of hitting the wall.

• Wearing layers is always a good idea, as it’s easier to calibrate your optimal clothing level when you have several thinner layers versus one thick one. If you’re going to train or race in cold weather frequently, it’s probably worth investing in some technical cold-weather clothing, especially if you encounter cold and wet conditions frequently. Here is our guide to winter clothing and what to wear for any given temperature.

• I’ve always felt that bitter cold is not as bad as 33° and rainy, since rain can make otherwise warm clothes useless. Here are my expert tips if you find yourself running in the cold rain often:
  • Buy some latex gloves. Latex is water proof and you can wear the latex gloves under or over your mittens. This will keep your hands dry. Once they get wet, your fingers are going to hurt!
  • Wear tight clothing. Loose clothes will sag more and weight you down. Not only will tight clothes feel more comfortable, but because they are closer to your skin, they can create a layer of warmth similar to that of a wetsuit.
  • Put Vaseline on exposed parts of your skin. Vaseline is water-resistant and it will help keep you warm if it’s windy.
  • Put newspaper in your shoes immediately after your run. The newspaper will soak up the water and help your shoes maintain their structure. Do not put shoes in the dryer or the oven – it will shrink the material and lessen their shelf life.

• It’s probably better to start out a race or workout with a bit too much on, since you can always take something off during the race. Many larger races donate clothes found along the course to charity. Take a trip to your local thrift store and but a few $2 sweatshirts you can wear and throwaway mid-race without concern.

• If you have trouble staying motivated in the cold, read this 5 tips for winter running motivation.

• Finally, it will probably pay off to be realistic: just like you can’t expect to run at your best when it’s 95° out, the same goes for a 15° turkey trot. While you may not hit your PR, you can still get a competitive edge on other runners who aren’t prepared for the effects of cold temperatures.

Get more great injury prevention advice from John Davis (plus other great training & maintenance tips from Jeff Gaudette & Co) on the RunnersConnect blog.