We spent months really pushing our limits while testing each pair of long underwear. We hiked, climbed, ran, slept, biked, and skied in each garment. We took them from the high mountains of Colorado and the Eastern Sierra to the cold oceans of the North Sea. Below we outline considerations that went into evaluating each metric.
Warmth
We carefully observed and researched the fabric and makeup of each pair of long underwear, including fabric weight and gauge. In addition to simple observations, we braved the elements in these undies when it got cold. We tested extensively while living out of a truck in Yosemite Valley and Indian Creek. We even endured sub-zero temperatures and hiked uphill whenever we could see our breath. Ultimately we busted our buns to the point of sweat and then just sat around to see which pair of long underwear kept us the warmest while in motion or standing still.
Breathability
We performed a few different tests in order to assess breathability. First up, we took each pair on a one-hour trail run to objectively measure which products successfully wicked moisture away from our skin and released the moisture through the fabric. If any fabric retained moisture, we noted the amount of time each layer required to dry, in addition to which layers were able to dry on the body. Finally, we evaluated the porosity of the material, recording which fabric allowed the wind to cut right through to provide ample evaporation.
Comfort and Fit
To look at comfort, we observed the comparative fabric softness and thickness of each product. We touched them, wore them against our skin for numerous days on end, and noted which felt the most comfortable when dry and wet. We slept in each pair of long johns, noting which garments were soft and cozy in comparison to some garments that caused irritation and itching.
To look at fit, we had several different women of all shapes and sizes try on the different layers. We noted relative leg lengths and the elasticity of the hems around the calf and the waist. We also looked at the fabrics to see if they stretched or had enough structure to maintain their shape after several adventures between washes. We noted the effectiveness of the waistband and whether or not it provided structure without decreasing comfort. Finally, we noted which garments fit true or size and which ones felt necessary to size up or down. After performing these tests, we are able to provide accurate recommendations for comfort and fit.
Durability
To test durability, we evaluated the craftsmanship and construction of each piece, noting if there were any pilling or stitching flyaways throughout the testing period. Also, to go above and beyond, we wore each piece on its own and under several layers. We noted if there was an area of high abrasion or holes that developed during our testing period. Also, we indicate if any holes became apparent in the fabric after just a minor snag. To that point, we must note that long underwear is not designed to be worn on its own — it's designed to be used with another thicker, more durable overlayer. These tests just allowed us to see which fabrics were more fragile than others. Lastly, we noted which layers were odor free and which layers became smelly after minimal use.
