by Tim Curry, MS ACSM-RCEP

As the mountain bike season comes to a close many athletes begin to anticipate whilly weather and snow. The winter season can make training outside an uncomfortable experience. Faced with inhospitable conditions, many cyclists hang up their bikes for the season or move to an indoor trainer. Similar to training in hot conditions, there are proven approaches to successfully adapting to changing seasons and preparing to hit the trails safely in colder temps, all while having fun. Let’s start by understanding what cold weather does to our bodies.

Effects of Cold on the Human Body

Anyone who completed outdoor activities in cold weather can tell you attest to the effects on our bodies. Exercising in the cold can often be summed up in two words: slow and hard. We may feel slower than normal, it can feel harder to breathe, and our perceived exertion level increases, all of which can make it easier to “bonk”. These sensations can be explained by examining what’s happening physiologically to our body’s systems:

  • Pulmonary - The bronchi of our lungs are covered in cilia which move and sweep the mucus we produce up and out of our lungs. This action helps “clean” our bronchi since the mucus traps particulates that the cilia remove from our system. Exposure to cold air slows down this sweeping action, which can lead to increased coughing as a mechanism to help expel mucus. Normally, breathing through our nose helps humidify and warm the air, hence reducing this effect. However, during exercise, it’s not always possible to breathe solely through our nose. This can create the sensation of more labored breathing and having to cough (and expel) more mucus.

  • Cardiovascular - Exposure to the cold causes our body to vasoconstrict peripheral blood vessels in our arms and legs. This pushes blood back to the torso to ensure adequate perfusion to the internal and vital organs, including the heart and brain. This action means our limbs have a relative lack of blood flow and with it oxygen and fuel (carbs and fat), which is the opposite of what is needed for exercise. 

  • Nerves - As parts of our body begin to drop in temperature our nerve conduction slows down. Many people assume this means our reaction time slows down, but it is far more complex than just one change. We have sensors in various parts of our body called proprioceptors. These sense changes in things like pressure, tension, force, and stretch, and allow our brain to monitor how our body is moving. As our body becomes colder the signals from proprioceptive sensors slow, leading us to feel and become less coordinated. If our body reaches the point of shivering our coordination becomes even more impaired. 

  • Tissues - When we encounter colder temperatures our tissues become more viscous (i.e. less pliable or more ridged). This presents two issues. First, it’s harder to move these tissues (muscles, tendons, ligaments, etc.). Second, the tissues are more prone to injury. 

  • Metabolism - Cold can drastically alter our metabolism during an activity. The power we can produce during the activity is reduced. The oxygen cost (how much oxygen we use) increases and we preferentially metabolize more fat (vs. carbs). This may seem beneficial, however, producing high power/pace requires carbs to produce the fuel muscles need, meaning these higher outputs become restricted. The act of shivering can also drastically increase our Caloric expenditure, burning through our bodies’ carbohydrate reserves and increasing the chance of “bonking”. 

  • Brown fat - This unique type of fat, found in the shoulder region of the body, can metabolize fat from other stores in our body to create heat and regulate our body temperature. When the body experiences cold weather this fat can become very active to help maintain body temperature, leading to an increase in fat usage.

Changes like these can have a broad impact on our ability to perform at the level we desire. Thankfully there are steps we can take to help mitigate negative effects on performance.

Is Acclimating to Cold Weather An Option?

You may already be familiar with the various procedures already outlined on how to train in the heat. If you’re aware of this approach already you might logically assume that performing a similar procedure would help us acclimate to cold environments. Unfortunately, there’s a bit of bad news if you’re planning on that approach. The data indicates that we have little to no adaptation to cold exposure. In fact, the only solid adaptations that have been documented are a drop in personal perception of how cold it is and, with longer exposures, an increase in the size and activity of brown fat stores with long-term cold exposure. As many athletes do not have consistent exposure to cold this is unlikely to impact the general population, therefore, we must look to other options to help mitigate the impact of the cold on our athletic performance.

Best Practices for Cold Weather

Given that we have many cold-weather sports and that cyclists can and do train outside during the winter, there are several best practices we can follow to reduce the impact of cold on our bodies:

  • Extend your warm-up -  Cold weather necessitates an extended warm-up. When you’re training or racing you should extend your warm-up in addition to incorporating a more gradual increase in intensity. This prolonged duration will help increase body temperature, including in the working tissues and nerves, and increase blood flow which helps with the delivery of oxygen and fuel. This may also reduce the likelihood of injury, though the data is mixed on this point. 

  • Layer up with technical fabrics - Layering clothing made from technical fabrics is critical. Technical fabrics (such as lycra) transport moisture away from the skin and help maintain body temperature. When we layer these clothing items we effectively create an external thermostat, giving us more temperature control. Stacking a base layer, a short-sleeve jersey, a long-sleeve jersey (or fleece), and a wind layer allows you to remove or unzip layers as needed to control how warm or cold you are. Just be sure not to over-layer! If we become too hot our body’s increased sweat rate can become more than what can be wicked away effectively. These sweat-soaked layers are not very comfortable and result in accelerated heat loss leading to us becoming even colder! A good approach is to begin your exercise wearing just enough layers so that you are slightly cool or cold at the start. This allows your body heat to increase naturally during exercise while remaining comfortable (without overheating).

  • Wear a mask or cover over your mouth - Wearing a fleece or lycra fabric cover over your mouth can help slow down incoming air. This provides a buffer for cold air to heat up before it hits the lungs. Wearing a thermal facial covering works especially well but isn’t always practical due to the rate of breathing during exercise, especially at higher intensities. A way around this issue can be to use a neck gaiter which is easily adjusted as needed. It’s easy to pull the gaiter down during intervals and higher intensity efforts and pull it up during warm-up or recovery periods. This provides you the option of covering your mouth as needed to reduce the impact of cold air on the bronchi.

  • Look at the weather forecast - This basic step is often ignored by many people and can lead to an unnecessary impact on performance. Nothing is worse than being halfway through a ride and suddenly finding the wind picking up from a breeze to a steady 20 mph only to realize you don’t have enough layers to stay warm. Utilize a high-quality weather prediction site, such as NOAA, to assess what to expect on your ride. This may mean packing an additional layer if the conditions are predicted to change during your ride. 

  • Eat and drink regularly - Many people reduce the amount they eat and drink in cold environments. However, as we just learned, we are going to expend more fuel in the cold and we actually can lose more water through our breathing. Therefore, you need to maintain your eating and drinking as you normally would; you can learn more about the recommended practices here

  • Have a backup plan - Cold environments have the potential to be particularly dangerous for anyone. In hot environments, we can simply find shade and stop exercising to help shed heat, at least up to a point. However, in cold environments, it’s not as easy to correct temperature issues (for example stopping mid-activity in colder weather will make certain issues worse). Therefore, always know where you could stop on your ride to get help or warm up. This could be as easy as going into a gas station. It is also a good practice to let another person know where you are going so that you can get help if needed. Sharing a live track of your ride through something like Strava or Garmin Live Track can help a person locate you if you need help quickly. Finally, it is a great idea to purchase and carry an emergency mylar blanket; these small but highly heat-reflective and inexpensive blankets can help you maintain warmth for longer and buy you time to get help.

Cold weather does not have to spell the end of exercising outdoors. Cold-weather riding can be a rewarding experience with the right preparation. Understanding and using these practices can help extend your outdoor training time and ensure you stay safe and have fun out on the trails. 

To learn more about the concepts covered in this article while earning NICA CEUs, check out our recommended courses below!

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