VO2 Max
VO2 Max (maximal oxygen uptake) is the maximum rate at which the body can consume oxygen during intense exercise. It is the gold standard measure of cardiorespiratory fitness, representing the upper limit of the aerobic energy system's capacity. The metric is expressed as milliliters of oxygen consumed per kilogram of body weight per minute (mL/kg/min). Wearable-derived VO2 Max is an estimate based on heart rate responses and activity patterns, not a direct measurement from exercise testing.
Typical Adult Ranges
mL/kg/minBased on population studies. Individual needs vary by age and health status.
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Key Takeaways
Represents estimated maximum aerobic capacity.
Higher values indicate greater cardiorespiratory fitness.
Derived from heart rate and activity data, not direct testing.
Changes gradually with training or detraining.
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How It's Measured
Oura estimates VO2 Max using algorithms that analyze heart rate data during activity and rest.
Common Influences
Training history: Sustained aerobic training improves VO2 Max; detraining reduces it.
Deep Dive
VO2 Max represents the ceiling of aerobic capacity—the maximum rate of oxygen delivery and utilization during maximal effort. Higher values indicate greater aerobic fitness; lower values indicate reduced capacity.
A useful framing is that VO2 Max reflects the efficiency of the entire oxygen delivery chain: lungs taking in air, blood carrying oxygen, heart pumping blood, and muscles extracting oxygen. The metric integrates cardiovascular, respiratory, and muscular function into a single fitness indicator.
During exercise, oxygen demand increases with intensity. The body increases cardiac output (heart rate × stroke volume) and oxygen extraction to meet demand. At maximal effort, these systems reach their limits, and oxygen consumption plateaus—this plateau is VO2 Max.
VO2 Max is determined by central factors (heart's pumping capacity, blood volume, hemoglobin) and peripheral factors (muscle capillary density, mitochondrial content, oxidative enzyme activity). Training can improve VO2 Max by enhancing these components; genetics sets the upper bounds.
VO2 Max declines with age, approximately 10% per decade after age 30 in sedentary individuals. Regular training can attenuate this decline. The metric is strongly associated with cardiovascular health and all-cause mortality in epidemiological studies.