VO₂ Max: The Science Behind Ski Mountaineering and Aerobic Fitness

VO₂ max is an important measure of aerobic conditioning, whether you’re an Olympian or just a person hoping to stay healthy. When ski mountaineering, or skimo, debuts at the 2026 Winter Olympic Games Milano Cortina in Italy on Thursday, athletes will face off in a brutal test of aerobic capacity. They will schlep their skis up a snowy mountainside that is twice as steep as a typical incline treadmill’s highest angle. And as they do so, they will move up to 10 kilometers per hour uphill while they suck lower-density, high-altitude air and carry more than 4 kilograms of gear. Such challenges require off-the-charts aerobic conditioning, as demonstrated by their “VO₂ max”: the maximum amount of oxygen the body can use per minute during all-out exercise.

Watching from the couch, many people may see no connection between these physical feats and their own workouts. But VO₂ max is a key marker of performance and health for both high-level athletes and regular people, says Jill Kanaley, an exercise physiologist at the University of Missouri, who studies the key fitness measure. “The higher your VO₂ max, the better you’ll perform in a race or everyday life,” she says. Here’s what skimo teaches us about VO₂ max and why it matters.

Ski mountaineering is the hot new event at the Winter Olympics. But how do competitors run uphill on skis? Well, it all has to do with Angora goats and their fabulous manes. VO₂ max reflects how efficiently the lungs move oxygen to the blood vessels and how well the vessels relay that oxygen to the muscles for intense exercise. According to the American College of Sports Medicine, VO₂ max is the gold-standard measure of cardiorespiratory fitness. The average 40-year-old’s VO₂ max is around 35 milliliters per kilogram per minute. For some ski mountaineers, by contrast, it’s in the 80s.

Skimo sprinters aren’t the only VO₂ max phenoms at the Olympics. Elite cross-country skiers have some of the highest VO₂ max values on record, with some having values above 90. Their numbers, on average, are similar to skimo racers, says Verena Menz, an exercise physiologist at the University of Innsbruck in Austria, who studies these athletes. (And it’s not just winter athletes with high VO₂ values—Tour de France cyclists have VO₂ maxes similar to those of skimo sprinters, too, and Norwegian triathlete Kristian Blummenfelt recently set what appears to be a world-record VO₂ max of 101.1.)

In addition to being aerobically-gifted, ski mountaineers must stride with massive force, delivered in under a half second per step—a cadence comparable to that of many recreational runners. Top skimo athletes have both high VO₂ max and explosive upper- and lower-body strength relative to their body weight.

VO₂ max isn’t just important for sports: an Olympic-level VO₂ max—whether in elite athletes or regular people—has been linked to exceptional longevity. Even a slight increase in a person’s VO₂ max can markedly lower their risk of premature death. Research that analyzed more than 122,000 adults over eight years found that each incremental increase between the lowest and highest VO₂ max was associated with longer survival.

It’s “much easier” to see improvement in low VO₂ max numbers than it is to improve an already higher value, says Kanaley, who trains people with diabetes in cardiovascular fitness. With basic exercise, previously sedentary people can increase their VO₂ max by about 20 percent, which helps them do tasks such as climbing stairs and walking hills, Kanaley says.

If you’re already moderately fit, increasing your VO₂ max requires a more specific training regimen: performing 75 to 80 percent of your exercise at moderate intensities and then doing the rest of your workouts at higher intensities—including maximum exertion—Menz says. For a runner, this might mean focusing a few sessions on relatively short, all-out efforts such as hill sprints.

VO₂ max is measured through a fitness test at a commercial lab, which analyzes gases from the nose and mouth that are captured by a mask. Scientists test skimo sprinters by rigging their labs to simulate uphill ski mountaineering specifically. “We always test athletes in a sport-specific manner,” Menz explains. Because sports-specific tests work the same muscle groups and movements that an athlete has been training, factors such as muscle fatigue won’t limit them before their cardiovascular system does.

VO₂ max isn’t the only attribute worth training for both Olympic and everyday fitness. Strength, balance and flexibility are just as important. The average person doesn’t need to track their VO₂ max, though; they just need to monitor whether their exercise performance changes during dedicated training. Take running a 5K, for example. “If your time improves over a period of six months,” Kanaley says, “so has your fitness.”

Ski mountaineers don’t judge success by their VO₂ max, after all. They judge it by their overall performance—and by the color of their medal.