You might be in for a shocking surprise the first time you run in frigid temperatures. Your feet, hands and head are protected, but when you breathe in, you feel a burning pain deep in your chest.
It's normal for your chest to hurt when you breathe in the cold air during a run. Your chest hurts because of the dryness of the cold air and the work your body is doing to bring it up to body temperature. This air is unlikely to do any permanent damage to your lungs. You may not be comfortable, but you're not doing yourself any harm.
Read More: The Best Cold Gear for Runners
What's Going on
Your body warms any air you breathe to body temperature — 98.6 degrees F — before it reaches your lungs. That air must be 100 percent humidified, too.
Warming and humidification starts with the mouth and nose and continues into the trachea, or windpipe. Your trachea is part of your airway and attaches your voice box to your lungs. The very base of the trachea sits in your chest.
In very cold weather, the cells that line the trachea kick into overdrive to humidify and heat the cold air that you breathed in. They must sacrifice their own water supply to moisturize the cold, dry air.
You won't notice it when you're outside for just a few minutes in the cold. However, when exerting yourself for an extended period of time during a run, you're asking these cells to continue to deplete their water. As they become more and more dehydrated, you start to feel a burning irritation in your chest and, sometimes, your throat.
Is It Dangerous?
Feeling the burning sensation isn't dangerous, but it can prompt bronchospasms if you suffer from asthma. Your lung tissue won't actually freeze, though.
For some people, the burning sensation lasts for just the first part of the run as your body becomes accustomed to the cold. Depending on the temperature, humidity of the air and how long you're running, the pain in your chest may also persist for much of your effort.
If chest pain lingers after your run or it presents in a way that makes you short of breath, consult your physician. Chest pain can indicate something's wrong with your heart, and running in the cold can exacerbate heart conditions.
Can I Prevent It?
Stay extra-hydrated in winter, so it's easier for the cells in your trachea to give up water to humidify and heat the air. Hydration in cold weather workouts is tricky because you aren't sweating as much. Aim to take a few sips of water every 15 to 20 minutes on runs of 45 minutes or longer.
Run at a pace at which you can control your breathing, too. Panting desperately to take in air increases the sensation of pain in your chest. Deep breaths cause less pain.
Read More: Is Jogging in the Cold Bad for Me?