What VO₂max Actually Tells a Nordic Skiing Family—and What It Doesn’t

Your Garmin says your VO₂max is 50. That sounds precise. Scientific, even. But what does 50 actually mean? Is a higher number always better? Does it mean you’ll be faster on skis? And what are we supposed to make of VO₂max numbers appearing on our kids’ watches?

For Nordic skiers, these are particularly interesting questions because cross-country skiing places extraordinary demands on the aerobic system. But VO₂max is also one of those numbers that becomes less simple the more closely you look at it. The short version is this: VO₂max tells us something important about the size of our aerobic engine. It doesn’t tell us how good we are at skiing.

So What Exactly Is VO₂max?

Imagine skiing up a long hill. Your muscles need energy to keep you moving, and to produce much of that energy aerobically, your body needs oxygen. That oxygen has quite a trip to make:

air → lungs → blood → heart → muscles → mitochondria

Your lungs bring oxygen in, your blood carries it, your heart pumps oxygen-rich blood toward the working muscles, and those muscles use oxygen as part of the process of producing aerobic energy. As you ski harder, your muscles demand more energy and your oxygen consumption increases. Eventually, you approach the greatest rate at which your body can deliver and use oxygen. That upper aerobic capacity is essentially what VO₂max describes: the maximum rate at which your body can take in, transport and use oxygen during very hard exercise.

One way to picture it is as a delivery network. Your lungs are the receiving terminal, your blood is the delivery fleet, your heart is the central pump, your blood vessels are the roads, and your muscles are the customers. VO₂max gives us an idea of the maximum capacity of that entire system.

What Does a VO₂max of 50 Actually Mean?

VO₂max is commonly expressed as milliliters of oxygen per kilogram of body weight per minute, or mL/kg/min. Suppose your VO₂max is 50. At maximal aerobic effort, that corresponds to approximately 50 milliliters of oxygen per kilogram of body mass every minute. For a 70-kilogram skier, 50 × 70 equals 3,500 milliliters—or 3.5 liters of oxygen per minute.

There is an important detail hiding inside that calculation. The number most recreational athletes see is relative VO₂max, because oxygen consumption has been divided by body mass. There is also absolute VO₂max, usually expressed simply as liters of oxygen per minute. If your body weight changes while your absolute aerobic capacity stays exactly the same, your relative VO₂max changes anyway. So the familiar number isn’t determined solely by your heart, lungs and muscles; body mass is part of the calculation too. That becomes especially important when comparing people of different sizes—and even more complicated when we start talking about growing children.

Why Nordic Skiing Is So Closely Connected to VO₂max

Cross-country skiing is fascinating from a physiological perspective because we’re using large amounts of muscle in both the upper and lower body while the terrain continually changes the effort required from us. We climb, descend, accelerate and recover. Different skiing techniques place different demands on the body, and races can combine long duration, repeated high-intensity efforts, cold conditions and sometimes altitude. That combination creates exceptional demands on the aerobic system and is one reason elite cross-country skiers have been studied so extensively by exercise physiologists.

And the research reveals something particularly interesting: during races, cross-country skiers can produce uphill work rates corresponding to roughly 120–160% of VO₂peak.

Wait. How can you ski at 160 percent of your maximum?

You aren’t actually consuming oxygen at 160 percent of your VO₂max. Instead, the work required during those sections is greater than what your aerobic system could supply at VO₂max, so anaerobic energy helps make up the difference for a short period. Then comes a descent and an opportunity for some recovery. Anyone who has raced—or simply tried to keep up with someone faster over rolling terrain—knows the feeling even without knowing the physiology: hammer up the hill, crest it breathing hard, tuck down the other side, recover, and then do it again.

A Bigger Engine Doesn’t Automatically Make a Faster Skier

This may be the most important point in the whole discussion. Imagine two skiers. Skier A has a VO₂max of 60 and Skier B has a VO₂max of 55. Who is faster?

We have absolutely no way of knowing from those two numbers.

Skier B might have better technique, better skiing economy, a better ability to sustain a high percentage of maximum aerobic capacity, greater muscular endurance, better pacing, better downhill skills, better skis that day, or simply make better tactical decisions. Endurance research reinforces this distinction: athletes can improve performance through changes in economy, efficiency and other submaximal factors even when VO₂max changes relatively little.

For Nordic skiing, technique makes this particularly easy to see. Watch an experienced skier glide past a strong beginner. The beginner may have a perfectly capable aerobic engine—and may actually be working much harder—but plenty of that energy isn’t being translated efficiently into forward motion.

That’s why we like the engine analogy: VO₂max tells you something about the size of the engine. Technique helps determine how effectively you turn that engine into glide.

How Is VO₂max Actually Measured?

A laboratory VO₂max test looks very different from checking your Garmin. An athlete exercises progressively harder—typically on a treadmill or stationary bicycle, although researchers can also use more sport-specific equipment—while wearing a mask connected to gas-analysis equipment. As the workload increases, the equipment analyzes respiratory gases and determines oxygen consumption until the athlete approaches maximal effort.

The important word here is measures. The laboratory is measuring respiratory gas exchange. Your watch isn’t.

So What Is Garmin Doing?

A Garmin VO₂max number is an estimate. Your watch doesn’t have a miniature exercise-physiology laboratory inside it. Instead, its algorithms estimate VO₂max from variables the device can measure or derive, including heart rate and exercise performance. Garmin also requires particular conditions before compatible devices generate VO₂max estimates, and cycling estimates require compatible power data.

That doesn’t make Garmin’s number meaningless. It simply means we need to understand what the number is—and what it isn’t.

A major systematic review and meta-analysis examining wearable VO₂max estimates found almost no average bias for exercise-based algorithms. At first glance, that sounds fantastic. But averages hide an important detail: for individual people, the limits of agreement were roughly 10 mL/kg/min in either direction.

That means an algorithm can perform very well on average across a large group while still being substantially wrong for one particular person. So if Garmin says your VO₂max is 52, don’t interpret that as proof that a laboratory test would measure exactly 52. And it’s an even bigger stretch to conclude that you’re physiologically fitter than your skiing partner because their watch says 49.

So What Is the Garmin Number Good For?

Probably one of its most useful applications is much simpler: watch your own trend over time.

If your Garmin consistently estimated your VO₂max around 44 last year and, after months of training, consistently estimates it around 48 under reasonably comparable conditions, that is useful information. The exact number may not perfectly match what a laboratory would measure, but the trend can still help you follow changes in your fitness.

That is very different from standing around after skiing and comparing everybody’s Garmin numbers as though they were race results. A watch-generated VO₂max is much better viewed as one piece of your own longitudinal fitness picture than as a precise score for comparing yourself with somebody else.

For Nordic skiers, there is another complication: Garmin’s supported activity profiles, requirements and algorithms can change. Whether a particular cross-country skiing activity contributes directly to a VO₂max estimate depends on the device and Garmin’s current implementation. That is something worth checking for your particular watch rather than assuming every Nordic activity affects the number in the same way.

Is 50 a Good VO₂max?

This is probably the question everyone eventually asks—and it’s exactly where VO₂max articles often become misleading.

It’s tempting to search for a chart, find your age, locate your number and discover whether you’re supposedly poor, average, good, excellent, or superior. But there is no single universal VO₂max scale that works that way.

Age matters. Sex matters at the population level. Body size matters, particularly when relative VO₂max is being used. Exercise modality matters. Testing method matters. Reference populations matter. Treadmill and cycling measurements aren’t necessarily interchangeable, and different datasets can produce different reference values.

So a VO₂max of 50 doesn’t mean exactly the same thing for everyone, and putting it into a generic internet chart can create a false sense of precision.

If you genuinely need to compare a measured VO₂max with a population, the scientifically better approach is to use reference data appropriate to the person’s age, sex and testing method rather than a universal chart. And if the number comes from a Garmin rather than a laboratory test, remember that you are dealing with an algorithmic estimate in the first place.

For most recreational Nordic skiers, there may be a more useful comparison anyway: you versus you.

Is your estimated VO₂max trending upward over months of training? Can you ski the same climb with less effort? Can you maintain your technique longer before getting tired? Can you ski farther comfortably? Those changes can tell you far more about your development as a skier than whether an internet chart calls your number “excellent.”

And Then There Are Kids

This is where we would be especially careful.

Once children start wearing sports watches, it’s tempting to treat every new metric as useful information. More data must be better, right?

Not necessarily.

Children aren’t simply smaller adults when it comes to aerobic physiology. They’re growing. Body composition changes. Muscle mass changes. Biological maturation matters. And because the familiar relative VO₂max number is divided by body mass, growth itself complicates interpretation.

There is even an important terminology difference. Researchers frequently use peak VO₂ with children rather than insisting on VO₂max because children don’t always demonstrate the classic plateau in oxygen consumption traditionally used as evidence that a true physiological maximum has been reached. Pediatric exercise researchers also caution against simplistic VO₂max predictions and adult-style interpretation of children's numbers.

So we would be very reluctant to take a child’s watch-generated VO₂max, put it into an adult-style chart and start drawing conclusions about their fitness or athletic potential.

And from a skiing-parent perspective, there are so many things we would rather see a young skier develop: balance, coordination, technique, confidence on downhills, movement skills, gradually increasing endurance, comfort on skis, skiing with friends and, most importantly, a long-term relationship with the sport.

A VO₂ number can be interesting. It shouldn’t become a scorecard for a child.

Getting Faster Without Increasing VO₂max

Imagine that your VO₂max barely changes over a season but your technique improves dramatically. You waste less energy. Your skis glide farther with each movement. You can maintain good form later into a long outing. You descend more confidently, pace climbs better and spend less energy correcting balance mistakes.

You may become a considerably faster skier even though the number on your watch barely moves.

This is especially relevant for beginners. During the first seasons of Nordic skiing, improvements in technique and economy can be enormous. The same physiological engine can suddenly take you much farther and faster simply because you're using it more effectively.

A plateauing VO₂max therefore doesn’t necessarily mean your training has stopped working.

VO₂max Matters Beyond Skiing Too

There is another reason scientists care about aerobic fitness that has nothing to do with race results. Cardiorespiratory fitness is strongly associated with health outcomes in adults. A large 2024 overview encompassing more than 20.9 million observations found that higher cardiorespiratory fitness was consistently associated with lower mortality and chronic-disease risk.

There is an important distinction here too: these are observational associations. They shouldn’t be turned into a simplistic promise that increasing one individual’s VO₂max by a particular amount will produce an exact reduction in health risk.

Still, the broader message is important. Building and maintaining aerobic fitness matters for much more than skiing faster.

So What Should Nordic Skiers Do With the Number?

If your watch gives you a VO₂max estimate, there is nothing wrong with paying attention to it. We certainly find these numbers interesting too. But treat VO₂max as one metric among many, not an athletic grade.

Look at trends rather than individual readings. Try to compare measurements obtained under reasonably similar circumstances. Make sure basic information in your watch—particularly things such as maximum heart rate and personal data—is sensible, because the algorithms depend on their inputs. Don't assume cycling and running estimates are directly interchangeable, and don't assume a watch estimate is the same thing as a laboratory measurement.

Most importantly, put the number alongside things your watch can't summarize nearly as neatly: technique, pace, endurance, perceived effort, confidence and simply how skiing feels.

The Number Isn’t the Goal

VO₂max is genuinely fascinating. It helps explain why that long climb feels the way it does, why elite Nordic skiers have attracted so much attention from exercise physiologists, and how our bodies adapt to endurance training.

Modern watches have also done something remarkable: they’ve taken a concept that once mostly belonged in exercise-physiology laboratories and put it on millions of wrists. That makes VO₂max easier than ever to see. It doesn't necessarily make it easier to understand.

So pay attention to your number if you enjoy the data. Watch how it changes. Let it teach you something about your aerobic fitness. Just don't let it become the goal.

For a Nordic skier, some of the most meaningful improvements can't be summarized by a single number: climbing the same hill more comfortably, holding your technique together when you're tired, carrying more speed through a corner, gliding farther with each stride, skiing a longer loop than you could last winter—or simply realizing that a trail that once exhausted you now feels surprisingly easy.

And for our kids, perhaps the best measurement of all is even simpler: they finish skiing and want to come back again.