What Does VO₂ per Kilogram of Body Weight Mean?

Imagine you want to know how fit you really are—not just how fast you can run, but how efficiently your body works during physical exertion. That’s where VO₂ comes into play. It’s a measure of how well your body uses oxygen during exercise. The full term is VO₂ max/peak, which refers to the maximum volume of oxygen your body can take in per minute.

But here, we’ll focus specifically on VO₂ per kilogram of body weight—a measure that tells you even more about your fitness than the total VO₂ number alone.

What VO₂ per Kilogram Means

VO₂ per kilogram of body weight is usually expressed in milliliters of oxygen per kilogram of body weight per minute (ml/kg/min). This number shows how much oxygen your body can use per kilo of weight per minute when you're exercising at your maximum capacity.

Why per kilogram?
Because someone who weighs 90 kg will naturally use more oxygen than someone who weighs 60 kg—simply because they’re larger. But that doesn’t necessarily mean they’re fitter. By dividing oxygen consumption by body weight, you get a more fair comparison: it shows how efficiently someone’s body works regardless of size or weight.

An Example

Let’s say:

• Person A has a VO₂ of 3.5 liters per minute and weighs 70 kg.
  → 3,500 ml / 70 = 50 ml/kg/min
• Person B has a VO₂ of 4.2 liters per minute and weighs 100 kg.
  → 4,200 ml / 100 = 42 ml/kg/min

Although Person B uses more oxygen in total, Person A is fitter per kilogram of body weight. That means Person A can deliver more performance relative to their size—their body is more efficient.

Note: Age also plays a role. As you get older, your VO₂ values naturally decline. However, regular physical activity can slow this process significantly.

Wat kun je ermee?

• Als motivatie: Door je VO₂ per kilogram bij te houden, kun je zien of je conditie verbetert. Zeker als je sport of traint met een doel, is het een mooie indicator.
• Bij afvallen: Als je gewicht verliest maar je VO₂ (absoluut) gelijk blijft, stijgt je VO₂ per kilogram – je wordt dus efficiënter!
• Voor gezondheidsdoelen: Een hogere VO₂-waarde wordt gelinkt aan een lager risico op hartziekten, diabetes en andere chronische aandoeningen.

What Can You Do with This Information?

• For motivation:
  Tracking your VO₂ per kilogram can help you monitor your fitness progress. If you’re training with a goal in mind, it’s a great indicator.
• During weight loss:
  If your absolute VO₂ stays the same while you lose weight, your VO₂ per kilogram increases—meaning you’ve become more efficient!
• For health goals:
  Higher VO₂ values are linked to a lower risk of heart disease, diabetes, and other chronic conditions.

Conclusion

VO₂ per kilogram of body weight is like a personal "fitness score" that considers how heavy you are. It tells you how efficiently your body uses oxygen, which is key for endurance and overall health. You don’t have to be a top athlete to improve your VO₂—walking, cycling, swimming, or simply taking the stairs more often can already make a difference.

By knowing and understanding your VO₂, you gain a powerful tool to track and improve your fitness.

Note: While the questionnaire gives a rough estimate, if you want to know your exact VO₂ max/peak, we recommend a performance test with respiratory gas analysis. You can learn more about this through a comprehensive sports medical examination (USMO): Click here

Who Fills Out the FitMáx Questionnaire?

An interesting question! To gain insight into this, we looked at the age distribution of the visitors who completed the questionnaire online.

The bar chart next to this text provides an overview of this distribution. As you can see, the questionnaire is completed by people of various ages. This shows that interest in cardiorespiratory fitness is widespread and relevant across different age groups.

Whether you’re young and curious about your fitness level, or older and consciously working on your health—the FitMáx questionnaire offers an accessible way to gain insight into your cardiorespiratory fitness.

BMI (Body Mass Index) is a widely used method to get an indication of a person's body weight in relation to their height. The formula is simple: weight (in kg) divided by height squared (in meters). This results in a number that can roughly classify someone into categories such as underweight, normal weight, overweight, or obesity.

Limitations and Drawbacks of BMI

Although BMI is useful as a general guideline, it has important limitations:

• No distinction between muscle and fat – BMI only considers weight and height, without taking body composition into account. A very muscular person could be classified as “overweight” according to BMI, even if they have a low body fat percentage and excellent health.
• Not suitable for pregnant women – During pregnancy, body weight changes significantly due to the baby, amniotic fluid, and other physiological changes. In this context, BMI is neither accurate nor relevant.
• Doesn’t account for age or sex – People with the same BMI can differ greatly in health and body composition depending on their age and gender.
• Not a direct indicator of health – While a high or low BMI may sometimes signal health issues, it is not a direct measure of things like muscle strength, cardiovascular health, or metabolism.

In Summary

BMI is a useful tool for a broad estimation, but it should always be interpreted alongside other factors. For a more accurate picture of health and body composition, a doctor, dietitian, or sports coach can provide additional assessments and insights.

In addition to the age distribution of our participants, we also looked at where the FitMáx questionnaire is being completed. This provides an interesting view of the geographical spread of people who want to assess their cardiorespiratory fitness.

The chart next to this text shows the distribution of participants based on location.