Heading out the door? Read this article on the new Outside+ app available now on iOS devices for members! Download the app.

Ski mountaineering is a low-impact way for trail runners to maintain off-season fitness. Photo by Patitucciphoto.

It’s midnight, and some of the country’s strongest trail runners are gathered under a star-filled sky in the mountain town of Crested Butte, Colorado. Headlamps are glowing, and everyone’s itching to go. Another ultra? Well, sort of.

On this March 28, the temperature is in the teens, and Rob Krar, Stevie Kremer and dozens of other trail runners have traded their running shoes for carbon-fiber boots and lightweight alpine-touring skis. They’re about to head into the wilderness on an epic ski-mountaineering race called the Grand Traverse, which covers 40 miles and climbs 7,800 feet on its way through the Elk Mountains, to Aspen.

Kremer, Krar and others have discovered that when the ground is covered in snow, “ski mo” is one of the most complementary sports for trail runners.

“Ski mo can be as simple as moving uphill on skis at a ski area,” says Nina Cook Silitch of Park City, Utah, one of the country’s strongest ski-mo athletes and the only North American to have three World Championship medals in the hyper-competitive European ski-mo racing scene. “It’s a great endurance workout, and it gives your body a break from the pounding on the trails.”

How to Get Started

Ease into it, recommends trail runner and ski-mo racer Chloë Lanthier, a biomechanics and sports-rehabilitation expert and trainer. “Keep it moderate, keep it aerobic and do it no more than twice a week,” says Lanthier. “Applying or removing skins can be frustrating until you practice, so don’t bother with too many transitions between uphill and downhill. Instead, ski uphill for up to an hour.”

To learn proper skinning technique and how to execute efficient transitions, join a clinic, increasingly available in many mountain towns, or even search for YouTube videos.

Once you get the knack of moving on snow and feel comfortable with your equipment, consider mixing in anaerobic workouts. “Try skiing uphill as fast as you can for 30 seconds to one minute. Rest the same length of time, then repeat,” says Lanthier. “Mix it up to promote both anaerobic and aerobic fitness, each of which is critical when it comes to being a strong, versatile trail runner.”

Where to Ski Mo

Silitch recommends finding a local alpine ski area that allows for uphill travel—an opportunity that’s becoming increasingly common. (A list is available at www.ussma.org.) Ask around (try the local gear shop) and you may even find a group that meets regularly to skin uphill.

Silitch notes that novice racers shouldn’t feel intimidated, as U.S. events are often very informal. Many include clinics for those who might not want to compete, but still want to learn about the sport. There are usually recreational categories, and some even have a “Heavy Metal” division, for those using heavier backcountry gear. (See Take Your Mark, page 16, for ski-mo and other winter race options.)

Get the Gear

Ski-mo gear can be pricey, up to $3,000 or more for a full racing setup. Fortunately, getting started doesn’t need to tap out your credit line. Look for used gear at ski swaps in the fall, check for last year’s equipment on sale or head online to the forums at skintrack.com and utahskimo.org, where racers often offer deals after upgrading their gear. To get started, any alpine-touring or telemark setup with skins will suffice.

If you already enjoy skiing uphill and want to demo the new, lightweight gear, head to a ski-mo race in your area, where many companies have demo equipment available. Some shops that sell ski mo gear have demo setups you can try out.

Want to go right to the light, fast gear? Here’s what you’ll need:

1. Lightweight skis
Race skis weigh as little as 700 to 800 grams.

2. Tech bindings
Lightweight “tech” bindings such as Dynafits are the norm.

3. Race skins
Race versions have a parallel cut to improve glide, but can be tricky on sidehills with less edge coverage at tips and tails.

4. Light, small boots
Ski-mo race boots are like hiking boots—flexible and lightweight, weighing only 700 to 800 grams.

5. Race suit
Even if you’re not racing, ski-mo suits have lots of benefits. They are breathable and functional, with hydration and nutrition storage and special pockets for stashing your skins.

6. Everything else
Poles should be light and stiff, with a half basket to avoid slipping when pushing uphill. Skip the ski helmet, which will bake your skull, and go for a lightweight, airy climbing helmet. A ski-mo racing pack is a great addition, since it’s designed specifically for easily storing your skis when you’re hiking, or “booting” sections of trail.

Doug Mayer is a contributing editor for Trail Runner, and owner of Run the Alps tours.

Want to Know What It Takes to Finish at Western States? Just Ask Hellah Sidibe.

Find out what happened when this six-year run streaker and HOKA Global Athlete Ambassador took on an iconic ultramarathon in California's Sierra Nevada