Training for trail and ultra running doesn’t have to stop when the trails get covered with snow. The snow presents an opportunity for a low-impact cardio and strength-boosting cross training exercise known as skinning. Skinning is a form of skiing in which a fuzzy, synthetic skin is stretched across the bottom of a pair of skis to allow an athlete to ski uphill, remove the skins at the top of the mountain, and ski down.
VO2 Max Training
Skinning is an intense exercise. The majority of your effort is spent on an uphill grade. Like running, it is easy to vary your intensity as long as the grade isn’t too steep. In this activity, both hands and legs are utilized to power the body. This increases demand for blood to transport oxygen to more muscles. This new demand for oxygen use can aid in developing your body’s VO2 Max, which is measure of how quickly and efficiently you can use oxygen. 
The added weight of an all-terrain ski setup, plus the uphill climb, will be sure to get your major leg muscles firing. When the local trails are packed and icy, the skinning is a great alternative to get the vertical gain without the risk of slipping on an icy trail.
While running downhill, you subject your body to the repetitive pounding of multiples of gravity on your knees, quads, and feet. While skinning, your feet barely leave the ground, if ever- your “stride” is just a forward slide. After skinning to the top of your mountain, you’ll be skiing downhill and letting gravity work for you as you carve through snow. There’s no worrying about having to jump over rocks or roots here! Implementing a skinning routine also allows your body time to repair from a season of wear and tear from running while maintaining fitness.
Core + Upper Body
By using poles to propel yourself up the mountain, you’ll also be using your shoulders and arms. This can also translate into efficiency for using poles in the summer months (hello, big mountain races). Going downhill, you’ll be activating various stabilizing muscles in your hip complex, and building endurance for running down lengthy hills. With more stability comes greater strength and speed!
How it is Done
First things first, if you plan to skin (or alpine tour) outside of a ski resort, know the inherent dangers of avalanches and how to read the terrain and snow. Many mountain localities give backcountry skiing/avalanche training courses. It is highly recommended you take one if you have not before, both for your safety and the safety of other backcountry users.
Determine your primary training grounds. Will you be using resort hills or backcountry? Starting in the resort will be a lower startup cost, as you will forgo some of the required hardware for backcountry. Many resorts allow uphill access for free or steeply discounted pricing compared to a lift ticket. Backcountry is free to access, but a training course to familiarize you with how to read snow will cost a few hundred dollars. You’ll also have to obtain a packable shovel, probe, avalanche beacon, and potentially satellite communication.
When choosing skis, it is common, generally speaking, to use a wider powder ski in the backcountry and a narrower ski in the resort. Bindings for skinning can be all terrain (AT) bindings, which release at the heel and pivot at the toe. These are practical for beginners and can be budget friendly. They also double as downhill skiing bindings. Alternatively, a pin setup is much more lightweight, but requires special boots and can be a more costly setup.
Skins are the length of the ski, and nearly just as wide, only leaving room for the metal edges to be exposed for proper carving. One side is an adhesive, and the other is mohair or nylon, which is gritty in one direction but smooth in the other direction. Skins are clipped onto the tip of the ski, laid across the bottom, and clipped again to the back. When done, they are stripped off, folded up, and pocketed until the next use.
We recommend the Backcountry x G3 skins. G3 makes premium skins, but they partnered with Backcountry to bring a unique design, maintain the quality we love from them, and dropped the price too. Win-win-win.
For a skimo/skinning packs (and other trail running packs, jackets, and more) check out our partner, Ultimate Direction. They build their gear with an athlete-first approach, and we love their designs! These packs allow you to carry the skins, water, spare layers, and even your skis on your back.
Free Hill Training Plan!
Training for Snow Season
Get your legs in climbing shape and be ready to have a blast moving uphill (and downhill) on skis! Check out our supplemental guide to skinning preparation above and join in on the benefits of skinning! You’ll find two different hill workouts to build power and stability, and a variety of body-weight workouts to strengthen your core!
How has the skinning been going for you? Leave a comment below!
 House, Steve, et al. Training for the Uphill Athlete. 1 ed., Patagonia, 2019, p. 27.