Running Hot in the Cold
By Dr. Trish Murray
When you think of hypothermia, what comes to mind? Do you think of someone who’s had an unfortunate incident falling through thin ice? Or maybe some inexperienced and ill-equipped hiker who got lost or injured while climbing Mount Washington? Perhaps you might even imagine hard-core winter sports like ice climbing or backcountry skiing.
How about cross-country skiing or even long-distance running? Did you know that runners during several Boston marathons, including those in 2013 and 2018, were treated for hypothermia? Yes, believe it or not, hypothermia is a legitimate concern for long-distance runners and Nordic skiers alike. It is particularly prevalent when there is a mixture of wet conditions, wind, and outdoor temperatures below 50 degrees. Sound familiar? Welcome to the Mt. Washington Valley.
During these conditions—although you are raising your core temperature and producing heat—the combination of cold and wet conditions will eventually cool your body down too quickly, increasing your risk of hypothermia.
Although we typically think of harsh winter conditions, the outdoor temperature does not have to be below freezing for your core body temperature to drop below 95 degrees. Changing weather conditions in the mountains can catch outdoor enthusiasts off guard in any season. Exhaustion and dehydration can also contribute to the risk of hypothermia, so long-distance runners, hikers, or cross-country skiers are particularly vulnerable.
While subzero temperatures or freezing rain are obvious concerns, more subtle environmental changes, such as a sunset, a rainstorm, increased cloud cover or change in wind speed, can be enough to shift your body’s thermal balance, even on a pleasant day. It should also be noted that the whole process from mild exposure to severe hypothermia may take only a few hours … or less.
Don’t get me wrong—I’m not suggesting you should hang up your gear and stay indoors for half the year. By all means, get outside as much as you can and embrace the fun activities this beautiful valley has to offer! Outdoor recreation is a fabulous way to enjoy nature and stay fit. In this article, I’ll share some tips on how to do it safely.
One of the most important things to do to reduce your risk of hypothermia is to stay warm and dry. It may seem strange to think of people exercising outdoors suffering from hypothermia since they are actively moving. Shouldn’t this keep them warm? Unfortunately, if the extra heat produces sweat, it makes hypothermia more of a risk. If you’ve ever been running, biking, hiking, or even walking at a brisk pace on a cold day, you know the scenario. You leave the warmth of your house or your vehicle all bundled up for the elements because you know how cold it is outside. Once you get moving for any length of time, your core body temperature begins to rise and you produce heat, so you feel warmer. Your outside skin temperature, however, is still cold. The heat you’ve built up in your core rises to the surface, hits your skin, and begins to dissipate in the form of sweat.
Once you stop moving, you need to retain heat, but your body’s core temperature is still elevated. Your body is attempting to restore balance and continues to lose heat. If you were in a warm environment, your temperature would just go back to normal, but in a cold environment, if you lose too much heat, your body temperature then drops and you end up hypothermic.
Tips to Avoid Hypothermia
At the first sign of hypothermia, the priority is to get warm, dry, and get your temperature back up! Wet clothing should be removed as quickly as possible. Blankets, extra dry clothing, drinking warm liquids and/or direct exposure to a heat source can be used to raise core body temperature. If symptoms worsen, seek emergency medical attention.
- Dress in thin, waterproof layers moisture-wicking fabric
- Bring a hat and gloves
- Carry a daypack with extra supplies
- Instant hand and foot warmers
- Extra gloves and extra socks
- Warm the air you breathe with a neck gaiter or scarf
- Bring snacks and stay well hydrated with warm fluids
- Avoid alcohol and minimize caffeine
- Eat complex carbs
- Exercise with a buddy
- Tell someone where you’ll be and when you’ll be back
Risks of Hypothermia
Once warmed up, you typically feel warmer than the weather may otherwise indicate, and while exercising, your ability to perceive the cold may be impaired. An exercise physiology research study published in August 2021 in Physiology & Behavior, found that during low-intensity exercise in cold environments, people cannot as easily perceive decreases in their core body temperature as when they were not exercising. This research has implications for recreational activities in colder climates, such as hiking and skiing, suggesting that the possibility of accidental hypothermia should be taken into consideration.
Winter athletes may be at particular risk for hypothermia for several reasons: runners, bikers, or climbers typically dress for their sport, not for standing around in cold weather. It’s also not practical to be carrying around bulky winter clothing when engaged in these types of sports.
At the end of a long-distance exercise session—whether it be running, skiing, or hiking—athletes will be depleted. Exercise depletes blood sugar and hydration levels, and this can exacerbate symptoms of hypothermia.
Most serious long-distance athletes are relatively lightweight with little body fat. Super lean athletes typically have more difficulty maintaining core temperature due to a lack of insulation provided by fat and muscle mass.
Certain medical conditions, such as diabetes and thyroid disorders, adversely affect the body’s ability to regulate its own temperature and may also increase someone’s risk for hypothermia. In addition, children and the elderly are at greater risk because they are less able to retain body heat in cold conditions.
Signs of Hypothermia
Exposure to cold decreases blood flow to the extremities and reduces heat loss from the core in an effort to protect the vital organs. It also prompts the body to produce heat through involuntary shivering. In the early stages of hypothermia, a person feels cold, shivers, is apathetic and withdrawn, and demonstrates impaired athletic and mental performance. It is important to recognize and respond to these early symptoms to avoid more severe hypothermia. As core temperature continues to fall, symptoms could include confusion, irrational thinking or behavior, sleepiness, slurred speech, cramping, slow breathing, and a slow or irregular pulse. Severe hypothermia causes cardiac arrhythmia and may even result in cardiac arrest.
Mother Nature plays by her own rules in the mountains. You’re best to expect the unexpected! Whatever your favorite outdoor activities, it is important to stay warm and dry. Checking the weather forecast is helpful; but keep in mind, we live in New England, and as the old saying goes, “If you don’t like the weather, wait a minute, it’ll change.”
One of the best pieces of advice to prevent hypothermia may seem obvious. Dress in layers. Since hypothermia is more common during cold and wet conditions, the best layers are thin and waterproof. It’s also important to be more conscious of sweating in the cold, and select fabrics designed to wick moisture away from your body.
A hat and gloves are essential during cold-weather recreation. If it seems too warm when you first set out, or if you start getting too hot along the way, a small daypack can be helpful to store these items and extra layers of clothing, including an extra set of gloves and dry socks in case your feet get wet. Extra sets of instant-heat toe and hand warmers can also be useful pieces of equipment to have in your pack as a backup heat source.
Other Tips to Prevent Hypothermia
When exercising in the cold, warm the air you breathe with a neck gaiter or scarf. This is especially helpful if you have any kind of asthma or other respiratory concerns.
Stay hydrated, but avoid cold fluids and alcohol. Both of these will lower your body temperature. Despite the warming sensation you may get from booze, it dilates blood vessels, promoting faster heat loss. Keep in mind, you may not feel as thirsty in cold weather, so make a conscious effort to drink enough water. A hydration pack worn close to the body provides easy access and keeps water warmer than when stored in an external bottle in your backpack. Not to be a total buzz kill, but minimizing caffeine is also helpful, since it is a diuretic.
Eat complex carbohydrates to maintain steady energy levels. This is best done in preparation for exercise a couple of hours ahead of time and replenished during and after exercise. Some examples of complex carbohydrates to fuel up before include hearty soups, chili, baked potato, overnight oats with nut butter, and berries or lean meats. Snacks to throw in your daypack might include energy bars or gels, trail mix, sandwiches, or fruit.
Lastly, warm up your muscles before exercise—and for safety’s sake, buddy up with a friend or at least tell someone where you will be going and when to expect you back if you are heading out on your own. With just a little bit of planning and effort, you’ll be sure to have a safe, warm, and happy winter ahead. Enjoy it, and I’ll see you on the trails!