We spent months really pushing our limits while testing each base layer bottom. We hiked, climbed, ran, slept, biked, and skied in each piece. We took them from the high mountains of Colorado and the Eastern Sierra to the cold oceans of the North Sea. Below we outline what we specifically did to evaluate each metric.
We carefully observed and researched the fabric thickness and makeup of each pair of long underwear bottoms. In addition to simple observations, we braved the elements in these undies when it got cold. We tested throughout the Fall season, setting up camp outside as much as possible. We 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 to see which pair of long underwear kept us the warmest when in motion and when standing still.
Breathability and Drying Speed
We performed a few different tests in order to assess breathability and drying speed. First, we ran and hiked in every legging, both with and without additional layers. This provided us with excellent data on which products wicked moisture and allowed it to move through the fabric. Second, we evaluated the porosity of the material, recording which fabric allowed for the wind to cut right through to provide evaporation. Lastly, we performed an in-lab dryer test. In this test, we weighed the dry weight (in ounces) of each product. Then we dunked each underwater for one minute to simulate the pieces getting drenched in a downpour. This allowed us to see how much each absorbed. After that, we put each article in the dryer for 10-minute increments, weighing each along the way. We stopped the test when the product got back to its dry weight. This test provided an objective measure for us to calculate the drying rate of each layer.
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. In addition, we determined which just felt the most comfortable to wear all day.
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 and had enough structure to maintain their shape after running around in the woods for a few hours. After performing these tests, we are able to provide good recommendations for fit.
To test durability, we evaluated the craftsmanship and construction of each piece, noting if there were any pilling or stitching fly-aways 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.