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Fast, Light ‘Mountain Slipper’ Shoe

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For trail running, a flexible and free foot is a happy foot. I’ve tried custom insoles, custom shoes, and piles of little pads and inserts designed to “hold” and “support” my foot just right.

La Sportiva Vertical K shoes
Vertical K shoes are extra lightweight but have padding underfoot

And for me they were all terrible in the end. I’ve tossed them all away and now favor a simple, flexible style of shoe for all foot travel.

A new model from La Sportiva, the Vertical K, fits this mold. At first look the Vertical K appears more cushioned than I would usually prefer. But the shoe has a low drop, meaning it’s fairly flat inside and will promote the mid-foot stride I’ve come to adopt.

The heel height is 18mm, which is normal for trail-runners though higher than many minimal shoes. An injection-molded EVA foam midsole offers cushion and dampening from rough blows. The outsole is a soft and grippy sticky rubber.

Perhaps most standout, these shoes are incredibly light for a protective trail runner. Sample size models run around 7 ounces per foot — half the weight of many normal trail shoes. A wrap-around upper provides a tongue-less, slipper-like fit.

Styling is bold — the shoes’ flashy yellow soles have a toothy grin and the print type on the side screams LA SPORTIVA! over and over again. The whole shoe is wrapped in thin fabric, a covering that hides the laces and keeps debris at bay.

My first outing in the Vertical K was not a race or a mountain run but a long beach trek. We were filming on California’s Lost Coast Trail, and over two days I hiked 25 miles with camping gear and camera equipment in my pack.

Unique sole has sticky rubber for grip

I never had so much as a hot-spot on the trek, and I appreciated the foam midsole for the rocky sections of the trail. The light footwear worked great for moving fast on the hardpack low-tide sand and while scrambling over rocks when the waves crashed in.

On regular trail runs, the Vertical Ks are agile and fast. They are light and built for speed. Just don’t expect to “feel” the ground like you can with a lot of shoes in this category — the thicker mid-sole might feel muting to true minimalist freaks.

Caveats: If you insist on dry feet, look elsewhere. These shoes offer no water resistance to speak of. (However, they dry quickly when they do get wet.) Also, the soft rubber soles are great for grip, but they wear quickly. My shoes have about 100 miles on them, but already the rubber has visibly worn down. They will live for a long time still, though don’t expect these featherweights to be your 1,000-mile shoes.

The Vertical Ks cost $115, not cheap but less than some of the competition. Another warning: I found the sizing runs small — our size 12 test shoes fit me fine and I usually wear size 11.

In a lineup of minimal shoes, the Vertical Ks are unique. They offer minimal weight for what they are and they have a flexible fit as well as a low heel-to-toe drop spec (4mm). But the cushy shoe has more protection underfoot than true “barefoot” stock. For me, the balance struck between the two shoe types was just about right.

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