Why Innerwear is the Original Base Layer

Why Innerwear is the Original Base Layer

When it comes to staying warm in winter, we often concentrate on getting the puffiest jacket, the coziest sweater, and the most insulating pants. But when it comes to our underwear, many of us grab whatever is at the top of our drawer. This cavalier attitude to cold-weather skivvies could be causing you unnecessary shivers. Science shows that your bra and underwear choice (what we at BRANWYN call collectively “innerwear”) play a huge role in controlling your core temperature. 

Consider this anecdote: Famed ultrarunner Pam Smith was in the lead at the 2013 Western States 100-Mile Endurance Run when temperatures began to skyrocket to over 102 degrees. In order to stay as cold as possible, she doused her bra and shorts repeatedly with water. She slogged through the run with plenty of chaffing, but was able to clinch the win. 

This tactic helped Smith cross the line first—but it’s a classic example of “don’t try this at home.” Under normal circumstances, forcing your body temperature to plummet is not only uncomfortable but downright dangerous. When our Innerwear is soaking wet, our bodies lose heat at about the same rate as if we were completely immersed in water.  If temperatures dip even below 40 degrees, this can lead to hypothermia within one hour’s time. 

Read on to understand more about how naturally moisture-wicking Merino Performance Innerwear can keep you comfortable in chilly temperatures—and in some circumstances, could even save your life.

Your Underwear Rules Your Body Temp

If you’ve ever kept a polyester sports bra on too long after a workout, you know that the fabric next to your skin can induce full-body chills even when the weather is warm. Science backs this up. A 2020 study in the Textile Research Journal shows that the underwear you choose has a serious influence on your body’s microclimate. In other words, no matter what you wear over your bra and undies, your temperature will be driven in a big way by the skivvies closest to your skin. 


This may be even more true for women, as bras (not just bottoms) often come into our equation. One recent study in The International Journal of Environmental Research and Public Health looked at the effect of synthetic sports bras on skin temperature during a treadmill exercise session. While participant’s body heat initially increased during the run, their temperature plummeted during the cool down to even colder than it was before they started exercising. TLDR: Polyester sports bras can make you freeze.

Additionally, women tend to be more sensitive to temperature dips thanks to our body composition and our hormones. We naturally have a higher fat-to-muscle ratio which prevents our bodies from generating as much heat. And our hormone estrogen (one of the main female sex hormones) causes our blood to slightly thicken, which can impede the flow.

Staying Dry Can Save Your Life 

There are few things more thrilling than adventuring in a winter wonderland. But cold temperatures plus wet fabric next to your skin can have disastrous consequences that range from the bummer of a powder day cut short to a very serious medical condition. 

Water has the ability to snatch heat away from our bodies at a rate of up to 240 times faster than dry air. Keeping your skin dry as you sweat (especially in high sweat zone areas that your bra and underwear cover like your chest, armpits, and crotch), will help avoid any danger of becoming overly cold. According to the Centers for Disease Control and Prevention (CDC), more than 1,000 people die from hypothermia each year. Ever heard the phrase “cotton kills”? Wet clothes worn close to the body (like those made of cotton, a fabric which soaks through and dries slowly) is one of the leading causes of this dangerous condition. 

How Merino Innerwear Works for You 

Choosing BRANWYN’s naturally sustainable Merino wool Performance Innerwear will help you stay warm and dry, so you can play outside no matter the weather. That’s because Merino wool has an almost supernatural power to pull moisture away from the skin. 

Ethically sourced from sheep who can live comfortably in both frigidly cold and swelteringly hot temperatures, Merino wool has the ability to hold up to 30 to 60 percent of its weight in water without ever feeling wet. It’s simply the best way for your skin to feel dry, which is critical when temperatures dip. (It’s great for staying comfy in the heat, too). 

The next time you embark on a cold-weather adventure, make sure to pay close attention to your choice of bra and underwear. Know that starting with a Merino option like BRANWYN Performance Innerwear is the foundation of staying warm, dry and in extreme cases... alive!

 

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