Cold Weather Can Make Your Workout Less Efficient and More Risky

Special to The Washington Post / Ian McMahan

16:46 JST, January 14, 2024

With temperatures dropping, anyone who heads outside to exercise should remember that cold can affect both your safety and your exercise performance.

When it’s cold, the body adjusts by moving blood toward the core, the brain and important organs, and away from the skin and muscles. While this protects the brain and important organs, it also can limit exercise performance while increasing the risk of frostbite, breathing difficulty and hypothermia.

“Somebody who starts warm and goes straight into exercise at an intensity that is enough to raise body temperature is unlikely to experience problems with the cold,” says Mike Tipton, a professor of human and applied physiology at the University of Portsmouth. Problems are more likely, he says, when people become exhausted or injured in cold conditions and stop generating heat.

How much cooling it takes for the body to get cold, at least to a dangerous level, depends on multiple factors, including temperature, clothing, wind and exercise intensity. Crucial to both performance and safety are dressing appropriately and warming up sufficiently. Most important is not taking your safety for granted, experts say.

The American College of Sports Medicine urges “avoiding exercise if possible” when the temperature falls below minus-8 degrees Fahrenheit. And runners should take extra care. Because of an increased risk of breathing difficulties in cold temperatures, some experts recommend holding off on cardiovascular or endurance training when the thermometer falls below 5 degrees.

“All sports performed in cold ambient temperature, whether it be skiing, walking, running or a team sport . . . are associated with injury risk if not using appropriate protective clothes,” says Martin Burtscher, a professor at the University of Innsbruck’s department of sports science.

Shivering slows you down

The human body is designed to keep the core organs and brain functioning in cold conditions, not to optimize exercise performance. One of the body’s adaptations, shivering – small contractions of the muscles to generate heat – diminishes muscle function.

“Shivering uses the muscles needed for exercise and puts them to use as a heater,” says Tipton, and “this increases the oxygen demand of low-intensity exercise.” With higher-intensity exercise, he continues, shivering is suppressed, but as muscles cool, the blood flow to them is reduced and maximum aerobic capacity is reduced.

“Your exercise economy and efficiency changes, in that . . . for a given amount of exercise, you are consuming more oxygen if you are shivering in addition to exercising,” Tipton says.

And the decline is significant. According to a 2021 American College of Sports Medicine expert consensus statement on cold-weather exercise, for every 1.8°F drop in muscle temperature, there is a 4 to 6 percent decline in aerobic capacity, exercise time, and power or sprint ability.

But the metabolic changes triggered by the cold mean a shorter workout can trigger outsize effects – mostly due to the body trying to generate heat, both fat and overall calorie burn increase.

You can also learn cold-weather workarounds.

“There’s little evidence that actually the kind of impairments you see in terms of neuromuscular function, muscle efficiency, economy, that any of that adapts with repeated exposure to cold,” says Tipton. “But what does adapt is things like knowing the level of clothing that you should wear depending on what you’re doing and understanding the early signs of physical impairment, which means that you should stop and get out of the environment rather than just push on.”

Dress right, layer up

Typical cold-weather exercise clothing consists of three layers: an inner layer touching the skin that does not easily absorb moisture, but instead wicks it away to outer layers where it can evaporate; a middle layer, which provides the primary insulation; and an outer layer, which repels wind and rain.

Remember, too, that frostbite is a possibility, so protect vulnerable areas of your body (fingers, toes, extremities), and wear a face covering to prevent airway and lung irritation at below-freezing temperatures. “The primary considerations in dressing for cold weather exercise are protecting vulnerable skin areas from frostbite and planning for adjustments in clothing layers,” the authors of a 2022 paper on performance and injury prevention in cold weather wrote.

The following signs mean your body is getting too cold:

– shivering.

– skin numbness or loss of sensation.

– clumsiness or decreased coordination.

– chess tightness, wheezing.

– muscle tightness.

Remember to add or subtract layers based on the temperature and the intensity level of your workout to prevent overheating and sweating. Too often, people start exercising while still wearing an outer layer more appropriate for rest than action, which can lead to perspiring and chills once they get moving.

– Avoid wearing cotton layers, which absorb moisture and are difficult to dry.

– Wear a face covering to prevent airway and lung irritation at below-freezing temperatures

And, think about your footwear. It’s important to wear shoes with excellent traction, because roads, sidewalks and running paths can get very slick, very fast.