Throughout the winter, there is no shortage of cold weather activities to choose from. You might go skiing, skating, snowshoeing, sledding or simply take your walk or run outdoors. These are more than just fun winter pastimes. A study in the Journal of Clinical Endocrinology & Metabolism found that cold weather workouts could burn more calories compared to those done in warm weather.
While exercising outside in the winter can be perfectly safe, it does require some extra precautions. The physiological and metabolic impact of exercising in cold weather can be intense. The body needs to work harder to perform in a harsher climate and be able to generate adequate heat to keep warm.
When the body is exposed to a significant change in temperature, elevation or intensity, its initial need for energy increases, so it breaks down glycogen, a form of carbohydrate, in the muscles.
“Glycogen is our body’s primary source of stored energy that is available for use immediately,” said Julie Lois, RD, CD, sports dietitian with the Froedtert & the Medical College of Wisconsin health network. “Due to this initial breakdown, it becomes increasingly important to optimize nutrient intake before, during and after cold weather training/workouts to ensure adequate repletion of energy stores and optimize muscle function.”
Energy-Packed Foods for Fuel
The number of calories an individual burns during any exercise depends on many factors, including his or her level of physical fitness, height, weight, body composition, age and the type of exercise. For example, in a day of skiing, a person could easily expend up to 2,000 calories. Eating a hearty meal rich in carbs and protein two-to-four hours before a workout will give your body an optimal fuel source.
“After the first hour of activity, a carbohydrate-rich snack should be consumed every 30 to 60 minutes to replete energy during exercise,” Lois said. For this type of snack, she recommends eating:
- a peanut butter sandwich
- orange slices
- a banana
- an energy bar
- trail mix with dried fruit
If you plan to continue exercising the same day or the next day, eat a carb-and-protein-rich snack within 30 to 60 minutes of completing your workout. This will replete glycogen stores in the muscles and stimulate muscle repair. Recovery foods that Lois recommends include:
- low-fat chocolate milk
- a fruit and yogurt smoothie
- graham crackers with nut butter
- an apple or banana with nut butter
A study of Navy SEALs participating in mountain warfare/cold weather training found they struggled to keep up with their body’s energy demands. The study looked at the SEALs’ energy expenditure and their energy intake and determined that increasing intake, primarily with carbohydrates, during planned breaks and downtime could help. While this is an extreme example, the research demonstrates the importance of regularly replenishing nutrients during periods of physical activity in the cold.
“Your body will fatigue faster in the cold weather without adequate fuel,” said Julie Carpenter, a licensed athletic trainer at the Froedtert & MCW Sports Medicine Center and athletic trainer for the U.S. speedskating team. “The cold slows down all of your body’s chemical processes, including your nervous system’s ability to generate a muscle contraction.”
While physical activity in the cold requires more nutrients, exercising in cold weather will not necessarily cause an individual to burn more calories than in a temperate climate. Generally, exercising generates enough heat that the body should not have to engage in additional heat-generating mechanisms that burn calories, such as involuntary muscle contractions through shivering or the activation of brown fat cells, dark-colored adipose tissue found throughout the body containing stored energy.
Risk of Dehydration During Exercise
Dehydration during cold weather exercise carries the same risk as it would when exercising in the heat, but a person will not feel as thirsty. The cold diminishes thirst by up to 40 percent.
“Your blood vessels constrict when you’re cold and prevent blood flow to the extremities, like your hands and feet,” Carpenter said. “Blood vessel constriction is a warming mechanism that allows your body to draw more blood to your core.”
Research published in Medicine & Science in Sports & Exercise found this process of vascular constriction leads to reduced secretion of a fluid-regulating hormone called arginine vasopressin, or AVP, which leads to a decline in thirst.
Respiratory fluid loss and sweat (which can be less noticeable under winter layers than in the summer) also contribute to fluid loss.
“When you breathe in cold, dry air, your body warms and humidifies that air,” Carpenter said. “When you exhale, the vapor you see is actually fluid loss.”
The speedskaters Carpenter trains are accustomed to pushing their bodies to the limit in cold conditions. While the skaters usually practice indoors at the Pettit National Ice Center, they still have to take into account cold conditions at the rink. They also frequently compete outdoors.
“Whether they are skating indoors or outdoors, most of them wear a scarf over their face or a face mask to prevent dehydration and to keep their airways moist,” Carpenter said. “They also bring warm liquids, like tea, to encourage hydration.”
A good rule of thumb is for every hour of physical activity — in the cold or in the heat — the body needs 16 ounces of water.
Be Aware of Hypothermia and Frostbite
Exercising in cold weather can put the body at risk of hypothermia, which occurs when body temperature drops below 95°F. Consider the wind chill when preparing for cold weather activities. Plenty of layers and moisture-wicking clothing are the best defense, along with limiting exposure.
“The body does an excellent job of maintaining a constant temperature, but extended exposure to cold can overwhelm its auto-regulation mechanism,” said Matthew Chinn, MD, emergency medicine physician with the Froedtert & MCW Moorland Reserve Emergency Department. “Shivering is one way the body maintains its temperature. As hypothermia progresses, the body’s shivering mechanism may stop working, people may become confused and the heart can stop working normally.”
Frostbite can cause permanent damage to the body as skin, nerves and tissue freeze at the site of injury. A person’s extremities, such as their hands, feet, ears or tip of their nose are most vulnerable. Frostbite can occur on exposed skin in less than thirty minutes.
“The first signs of frostbite can be numbness, clumsiness and cold skin,” Dr. Chinn said. “The skin can also appear discolored or turn black.”
Gloves, warm socks and hats are good protection from the cold.
How Cold Is Too Cold to Exercise Outside?
Wisconsin winters can be brutal when it comes to cold temperatures. To avoid hypothermia and frostbite, move your workout inside if the temperature drops below 0°F or the wind chill reaches -17°F. You are unlikely to get frostbite when the temperature is above 5°F and the wind blows at less than 25 mph, according to the National Weather Service, but that risk increases substantially as the temperature drops and wind speeds pick up. Exposed skin can develop frostbite in 30 minutes at a wind chill of -19°F.
Prepare for Performance
To achieve peak athletic performance in cold conditions, research shows that consuming the right nutrients early and often and hydrating even when you are not thirsty will go a long way. Layered clothing to provide insulation and protection from the elements, as well as avoiding extended exposure to cold, will also protect you from certain dangerous conditions.
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thanks for that article. I was trying to find out why I get so exhausted hillwalking in severe windchill and you're the only person who's actually answered the question. I'll take more food with me in future.
This winter has been particularly rough trying to workout, especially with the pandemic and the gyms closed. I need to get out and do something for my mental health! I came across some exercise tips during the cold that were helpful , https://www.ez.insure/landing/2021/01/tips-for-exercising-outdoors/ . What are your thoughts?