Three miles into a humid, 11-mile run—just far enough that it was silly to turn back—I started to have regrets. They had been riding up the whole time, but as I got sweatier and slower, my soggy cotton underwear became a literal pain in the rear.
The suffering on any long-distance activity is repetitive annoyance—that sock that won’t stay up, the backpack that chafes or the song lyrics stuck in your head. But ill-fitting underwear might be the unseen torture device of outdoor sports. Over miles, the friction of a wedgie or the pinch of a too-tight waistband can be not only irritating but downright damaging.
Outdoor enthusiasts tend to spend a lot of time (and money) considering the breathability and technicality of the rest of our kits: debating the benefits of wool shirts over synthetic ones, refusing to run in shorts that are the wrong length, carefully selecting the perfectly-fitting shoes. But do we ever invest as much thought into what lies beneath? I think we should.
Undies seem so simple. They’re small, barely noticeable. But the layer closest to your skin bears some attention, especially if you’re spending a long time—and sweating a lot—in the same pair. In picking out the right underwear for active pursuits, consider these important factors and features.
Your mother may have told you to wear cotton underwear always. But as in many backcountry situations, cotton kills—or at least kills the mood—because it doesn’t wick moisture. The problem comes from sitting around in soggy bottoms. When you’re sweaty, especially on long runs when you’re in the same, swassy pair, or not changing often on a backpacking trip, all that moisture can build up bacteria that can cause things like yeast or urinary tract infections.
Synthetic materials like nylon are a good option for moisture management, since they dry faster and wick sweat away from your body so you don’t freeze. Wool has major benefits, too, like long-lasting durability and its enviable talent of reducing bad odors. Look for underwear made from a blend of fabrics, like Icebreaker’s Sprite Hot Pants for women, which are made from 83 percent merino wool, making them more resistant to stink, and they’re also non-itchy, thanks to added nylon and Lycra®. For men, SAXX’s Quest 2.0 Boxer Brief is stitched with a mix of soft, stretchy, nylon spandex for easy movement and polyester fabric that breathes when you get sweaty and doesn’t bunch.
You want your underwear to fit tight enough that they’ll stay put and not sag or rub, but not so tight that they’re pinching or creating humid environments where things get funky. Look for enough coverage that they’re going to stay put, but not so much that they’re bunchy.
Lightweight and full coverage, the ExOfficio Give-N-Go Sport Mesh Hipkini Briefs are a fan favorite for women who like fuller coverage. The mesh fabric allows for airflow, and the wide smooth waistband won’t roll down. ExOfficio’s Give-N-Go Sport Mesh Boxer Briefs for men has a just-right 6-inch inseam and a snug yet comfortable fit.
Mind anything that could chafe. A good rule is that if you notice it standing still, you’re really going to notice it when you’re moving for sustained amounts of time. Look for a waistband that stays put, flatlocked seams or laser cut pairs to minimize rubbing and binding from stitching. We like underwear you can forget about and the Smartwool Merino 150 Bikini for women fits the bill. It’s cut smaller than some other pairs but stays in place. Tagless options, like Patagonia’s Active Hipster Underwear for women, are a good choice, too.
For men, Patagonia’s Sender Boxers have a waistband that stays locked in place and cool-and-meshy recycled nylon that moves without rubbing. They also happen to contain recycled material and meet bluesign® criteria, if you like to feel smug about what’s under your pants.
As for me, I’m a technical underwear convert now on long runs. No more cotton underthings. No more sweat or bunching in places buried underneath. Finally, I can breathe free.