ALERT: Cold weather exercise comes with deadly health risks

Here’s how to beat the cold, dark days of winter—safely

A new winter season is here—and the temptation to hibernate looms large. But that doesn’t give you reason to boycott your exercise routine.  

Rather—it offers a time to get creative with your workouts. Especially if you love getting outdoors. 

Because whether you’re a cyclist, a runner, or even just a regular walker, the return of colder temperatures is a real game-changer. And according to recent research, hypothermia may be a bigger risk than you think…   

Exercise dulls cold perception 

Your body has many mechanisms for modulating its temperature—shivering, sweating, and dilation and constriction of blood vessels are just a few.  

This thermoregulation relies on sensors located in the body, which trigger responses to hot or cold surroundings. But cold weather exercise can throw a little wrench in the works. 

For one thing, your muscles generate heat—but that heat is lost more easily when temperatures are low. Research also shows that shivering kicks in later when you’re exercising than it does when you’re at rest. And sensation of skin temperature is lower, too—likely because of natural painkillers released by the brain during workouts (a phenomenon known as the “runner’s high”).   

What does that mean for you? Well, it’s a perfect storm for hypothermia to set in… that is, if you’re not careful.  

So, to better explore this impact, Japanese researchers monitored skin temperature, core body temperature, skin sensation, and cold perception—along with factors like heart rate, blood pressure, and oxygen uptake—in a group of healthy young men.  

They measured subjects at rest and during low-intensity exercise in a cold-water tank. And their findings serve as a timely warning to outdoor exercisers and winter sports enthusiasts alike… 

Even though the exercise wasn’t intense enough to trigger the “runner’s high” I mentioned above, subjects still saw reductions in perception of core body temperature by exercising in the cold. Meaning the exercisers couldn’t tell how cold they really were.1  

This may be a good thing when you’re only dealing with moderately chilly temperatures. But especially for older exercisers—or people of any age who enjoy activities like skiing or hiking in the snow—it’s not hard to see how these dulled perceptions could quickly turn dangerous.  

But that’s not the only danger of exercising in the cold…  

Winter weather is hard on your heart 

Cold temperatures cause your blood vessels to constrict. That’s your body’s way of conserving heat and staying warm. Ultimately, this leads to a pretty dramatic rise in blood pressure. In fact, studies on mice indicate that continuous cold exposure could raise blood pressure by as much as 50 percent within just five weeks.2 

The rise you’ll see depends on a variety of factors—temperature, wind chill, length of exposure, activity levels, etc. But researchers at the University of Florida have shown that spending just five minutes in 52-degree weather—which is hardly “freezing”—is enough to trigger significant spikes in blood pressure. And experiments indicate that these cold-related rises could last for hours.3 

But there’s also the problem of shorter days—and restricted access to sunshine. Scientists believe that this compounds the risk to your arteries. For one thing, lack of sunlight lowers your skin’s natural production of vitamin D. And low levels of this crucial nutrient have clear links to blood pressure elevation and heart risk. 

Plus, UVA sunlight exposure also triggers the release of nitric oxide (NO) stores underneath your skin.4 And NO plays a critical role in vasodilation—the relaxation of blood vessels that lowers blood pressure and allows your circulation to flow more freely. 

So, clearly, these small weather-related changes can snowball into major—even life-threatening—disasters. And unfortunately, recent studies illustrate that deadly domino effect in pretty terrifying fashion… 

Heightened risk of heart attacks and stroke 

Taiwanese researchers recently looked at data from nearly 300,000 people with atrial fibrillation. (This is the most common type of heart arrhythmia. And it can lead to stroke, heart failure, and sudden death.) 

They found that, over a three-year study period, risk of stroke was almost 20 percent higher in the winter months. Not to mention, even mild temperatures—anything below 68 degrees, which many people wouldn’t even consider “chilly”—were enough to boost stroke risk in this population.5 When temperatures drop below freezing, that threat only escalates.  

Another recent study looked at data from residents of Winnipeg, Canada over six years. And results showed that when the temperature dropped to 32 degrees or lower, rates of the severest, deadliest form of heart attack jumped by 16 percent.6 

Winnipeg may be one of the coldest big cities in the world. But it bears repeating that these are not polar vortex conditions we’re talking about here. And no matter how accustomed to winter weather you think you are, your body may have different plans.  

Benefits of the “cold” outdoors—and how to safely embrace it 

The natural conclusion here might be to move your workouts inside for the winter. But here’s the thing: There’s still a lot to gain from getting outdoors in the winter, as I discussed on page 3. 

For one thing, a daily dose of fresh air and sunshine can make a world of difference to your mental health, especially if you suffer from seasonal depression. Not only that, but research also shows that cold weather workouts can supercharge your stores of metabolically active brown fat. 

Back in 2014, a team of researchers in the Netherlands found that young men exposed to chillier temperatures in a lab setting for six hours daily adapted to this temperature drop within just ten days. Ultimately, they shivered less during cold-weather exposure, even with the thermostat set at a chilly 60 degrees.7 

As it turns out, regular exposure to cold was “turning on” these subjects’ stores of brown fat—which burns energy and churns out body heat.  

In fact, according to this research, brown fat activation could account for as much as 30 percent of your body’s energy expenditure. That’s a whole lot of calories. And all you have to do is embrace the cold… safely.  

So, let’s go over a few common-sense, cold weather precautions on how to do just that: 

• Work out during peak sunshine. The lunchtime hour is when the sun is highest—which means it’s also going to be the warmest part of the day. Try to schedule your outdoor activities then, if you can. 
• Dress appropriately. Always bundle up. Layering is a good idea especially if you’re going to be breaking a sweat. Look for wicking fabrics that will help keep you dry. And make sure your head, hands, and feet are warm with a hat, gloves, heavy socks, and appropriate footwear. 
• Warm up first. This gets your muscles ready to brave the cold, and reduces the strain on your heart. Light exercises like lunges, arm circles, and arm swings are a great way to prepare your body to go outside.  
• Stay hydrated. If you’re sweating, you still need to be drinking plenty of water, no matter what the thermometer says. I encourage you to drink a glass of water before, during, and after your workout.  

Finally, if it’s an especially cold, blustery, or frigid day, find a more temperate place to work out—whether it’s a gym, a mall, or your own living room. Warmer days will be back again eventually. Until then, we all have to find ways to get creative in (or out of) the cold.   

References: 

1. 1. Fujimoto T, et al. “Effects of low-intensity exercise on local skin and whole-body thermal sensation in hypothermic young males.”Physiology & Behavior, 2021; 240: 113531 DOI:1016/j.physbeh.2021.113531 
2. University of Florida Health Science Center. “Cold Weather Hikes Blood Pressure, UF Scientist Warns.” Science Daily. 9 February 2005.
3. ibid
4. Liu D, et al. J Invest Dermatol. 2014 Jul;134(7):1839-46.
5. “The relationship between cold temperature and risk of ischemic stroke in patients with atrial fibrillation.” Eur Heart J (2015) 36 (suppl 1).
6. “How cold is too cold: the effect of seasonal temperature variation on risk of STEMI.” Eur Heart J (2015) 36 (suppl 1
7. vanMarken Lichtenbelt et al. “Cold exposure — an approach to increasing energy expenditure in humans.” Trends in Endocrinology & Metabolism, January 2014