Most runners associate lower temperatures with faster paces. There is no denying that hot weather increases physiological strain and leads to slower running paces. However, colder temperatures do not always mean better running performance. While cooler, milder temperatures are ideal for performance, temperatures below freezing are not. This article will answer the question of do you run slower in the cold – and offer some tips on how to mitigate that effect during winter training.
Do you run slower in the cold?
Throughout this article, cold will refer to temperatures below freezing (32F/0C). Most runners will run well in mild weather; most marathon world records are set in the 45-55F/7-13C range. Periodically, records will be set in cooler temperatures (such as the new American record set at the Houston Half), but seldom are records set in truly sub-freezing temperatures.
The lower the temperature drops below freezing, the more profound the impact on your running. The colder it is, the slower you will run and the sooner you will fatigue.
According to a 2015 review in Comprehensive Physiology, you will experience up to a 5% decrease in oxygen consumption (VO2) when running in temperatures below 32F/0C. Likewise, a 2022 analysis of 7867 athletes across 1258 races found that for every degree Celsius below 7C, performance declines by 0.3-0.4% (For every 1.8F degree drop below 44F, you run 0.3-0.4% slower.)
The higher the intensity, the more profound this impact. 5K races (or interval workouts) will have a more significant degree of slowdown in the cold compared to easy runs. You’ll still run slower on easy days, but it may not be as profound.
The science of running in the cold
Why do you run slower in the cold? Running in the cold has a direct effect on all your physiological systems.
When you run in sub-freezing temperatures, your body experiences:
- Constriction of the blood vessels in the working muscles (peripheral vasoconstriction), which reduces oxygen delivery
- Cold muscle belly temperature, leading to reduced contraction power
- Constriction of airways (bronchoconstriction), which impacts breathing
- Increased sympathetic nervous system activity, to balance out the increased physical demand
- Lower fatigue threshold
- Higher lactate production and glycogen usage
Together, all of these changes impact how much oxygen you breathe in, how efficiently that oxygen is transported and extracted into the muscles, and how your body produces energy. The colder it gets, the more drastic these impacts, and the slower you run.
How to adjust your running for cold weather
If you do not adjust your gear, pacing, and nutrition for these changes, you will slow down even more and fatigue sooner. (Not to mention, it increases your risk of frostbite and hypothermia.)
Train by RPE or heart rate
Once you factor in the cold temperatures, wind, and potential ice or snow on the ground, you cannot easily calculate winter-adjusted training paces.
Instead of stressing about pace, use either rate of perceived exertion (RPE), the talk test, or heart rate to train in cold weather. If you are using heart rate, use a chest strap, as optical monitors are less accurate in cold temperatures (due to blood flow changes).
Train by time, not distance
Likewise, you can modify your training for winter by training for time, not distance. This approach can keep you from pushing hard to be done sooner.
Whether you are base-building or race-training, you can easily convert the distance to time. For example, if your normal easy pace is 9:30-10:00/mile, multiply the distance by 10 to get the training time target. A 5 mile run translates to a 48-50 minute run.
Take high-intensity workouts on the treadmill or indoor track
As mentioned above, cold weather will impact faster paces more significantly. Additionally, fast running in very cold temperatures (<20F/-7C) could increase the risk of muscle injuries.
You’ll feel better – and have a better training stimulus – if you take quality workouts indoors on very cold days. The treadmill is biomechanically and metabolically similar to overground running, so you can confidently do your workout on it (with or without a 1% incline.) The indoor track provides another option for indoor workouts.
Keep working muscles warm
Cold muscle temperatures will reduce force output, while also increasing risk of strain or other injury. You want to ensure your muscles are warm for optimal performance on winter runs.
There are two simple steps for keeping muscles warm on winter runs: warming up before your run and using clothing to warm working muscles.
A dynamic warm-up prior to your run elevates muscle temperature. If you spend 5-10 minutes performing leg swings, lunges, and other bodyweight movements, your muscles will be warmer by the time you start your run – and work more efficiently in the cold from the start. You can also incorporate some plyometrics or walking into your pre-run warm-up.
You want to keep those muscles once you start. While no one forbids you from wearing shorts, it is worth noting that in sub-freezing temperatures, leggings or pants will keep your muscles warmer and functioning better. (Bonus: lower risk of frostbite!) Read this full article for guidance on what to wear for winter running.
Got more winter running question: on heart rate, hydration, and if it’s okay to train on the treadmill? Tune into my YouTube video that answers your winter running questions!
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