This is a lightweight top that fulfills all of the demands of high intensity, low duration activities, but falls short in comfort for longer term use.
Sometimes winter climbing involves gymnastic stretches. In this instance the Under Armour Base 2.0 performed well.
Photo: Drew Smith
At 5.9 oz for a size medium, the Base 2.0 is the lightest base layer tested, and predictably, it is also the least warm. This is not as necessarily a bad thing. For hotter temps or high intensity workouts a less insulating top may be called for, but don't expect this shirt to do to well in the arctic.
What this long underwear lacks in warmth it makes up for in breathability. In this category it performed better than any other top. A designed tight fit stretches the fabric out against the skin, increasing the air space between fibers, and allowing more water vapor to pass through. Additionally, sweat that does condense is wicked away well by the checkerboard pattern of the inside.
As could be expected from one of the thinnest shirts reviewed, this top did well on our air dry test. It finished second behind the winner, the Patagonia Merino 2 Lightweight Henley, and was the top performing synthetic layer. This test was conducted with the tops hanging stationary from clothes hangers. In a real world scenario, we would expect this long underwear to dry even faster. The spaces between fibers would be expanded by the stretch of the tight fit and heat generated from the body could combine for really quick drying.
The waffled inner fabric of the Under Armour Base 2.0 helped it dry quickly and finish second overall in our air dry test.
Photo: Jack Cramer
The close fit that is great for increasing breathability and showing off your muscles limits layering ability. While this can be worn effectively as a next-to-skin layer, it is uncomfortable when worn over anything else.
The same thin fabric that makes the Base 2.0 quick to dry and breathable also makes it delicate. In our tests the material began to wear out at contact points on the sleeves and shoulders, pilling on the surface as loose fibers tangled together. This weakness to abrasion could be expected from any garment of similar weight and thickness, but it is something that shoppers with plans for hard use should be aware of.
Surface pilling starting on the sleeves of the Under Armour Base 2.0.
Photo: Jack Cramer
Comfort and Fit
The form fitting tightness of the Under Armour Base 2.0 caused it to ride up a little whenever you raised your arms.
Photo: Drew Smith
Under Armor was one of the first companies to popularize the tight fitting base layers that have become ubiquitous amongst athletic apparel companies. This popularity is difficult to understand given how uncomfortable this top is to wear. Some of our testers complained about irritation and constriction in the armpit. Additionally, whenever arms are raised overhead, the bottom rises up, exposing the stomach. Not uncommon for a shirt, but unlike other long underwear tested, which fell back into place, the tight fit on the Base 2.0 caused it to stay up even after the arms were lowered—leaving you looking like a belly dancer until you are able to pull it down.
To counter these drawbacks, some wearers suggest sizing up when purchasing Under Armor; if you're normally a medium, buy a large. While this may resolve some of the fit issues, it would negate the wicking and breathability advantages of a tight fit, and runs contrary to the company's advertising depicting muscular athletes showing off in skin tight clothing. We have yet to decide which strategy is worse.
Just like the commercials show, Under Armor is great for high intensity, low duration athletic activities like football, soccer, or other organized sports. For these uses, its strengths in breathability and wicking overshadow its deficiencies in durability and comfort, and it becomes an option worthy of consideration.
Currently at $55, this shirt is cheaper than most of the long underwear reviewed and identical in price to the Patagonia Capilene 3 Crew. Though that top offers a much better value; being both stronger and far more comfortable. For outdoor shoppers on a budget, we recommend the Cap 3 instead.
For organized team sports or early morning training runs, the Base 2.0, with its strengths in breathability and drying speed, is a viable long underwear option. However, during prolonged use the tight fit is likely to irritate, and its delicate fabric may not hold up to the rigors of outdoor use. Several of the other layers tested offer advantages in versatility and comfort for the backcountry traveler.
The Under Armour Base 2.0 on the South rim of the Grand Canyon.
Photo: Dave Cramer
Other Versions and Accessories
Under Armour Base 2.0 Crew - Women's
Base 2.0 Leggings
- Women's version of this shirt
- Base 2.0 material in legging form