VO2 Max
What VO2 max is
VO2 max (maximum oxygen uptake) is the maximum rate at which your body can consume oxygen during exercise, measured in millilitres of oxygen per kilogram of bodyweight per minute (mL/kg/min).
It is the gold standard metric of cardiovascular fitness. A higher VO2 max means your cardiovascular system can deliver more oxygen to working muscles, allowing you to sustain higher intensities for longer.
Lab-measured VO2 max requires a mask and running to exhaustion on a treadmill. Wrist-estimated VO2 max from Garmin and Apple Watch uses heart rate, pace, and movement data to produce an estimate — accurate to within 3–10% of lab values.
What the numbers mean
| Category | Women (mL/kg/min) | Men (mL/kg/min) |
|---|---|---|
| Below average | under 28 | under 35 |
| Average | 28–38 | 35–42 |
| Good | 38–48 | 42–52 |
| Excellent | 48–58 | 52–62 |
| Elite | above 58 | above 62 |
| (Approximate population percentiles — values differ by age; these are for ages 30–40) |
Elite endurance athletes (Tour de France cyclists, marathon runners) typically measure 70–90 mL/kg/min.
Why workout apps track it
VO2 max is a long-term fitness indicator. Improvements take 6–12 weeks of consistent aerobic work to register. If your estimated VO2 max is trending up over 3 months, your base fitness is improving regardless of how individual sessions feel.
Garmin Connect’s VO2 max tracking is the most accurate wrist-based implementation available, validated in multiple peer-reviewed studies to within 3–5% of lab measurements. The Training Status feature uses VO2 max trends alongside training load to classify your training as Productive, Maintaining, or Overreaching.
Apple Watch estimates VO2 max during outdoor runs and walking. Less granular than Garmin but sufficient for trend tracking.
Whoop does not estimate VO2 max — this is a deliberate product decision. Whoop focuses on recovery, not performance metrics.
The VO2 max vs HRV distinction
These two metrics are often confused but measure completely different things.
VO2 max: your fitness ceiling. Changes slowly over weeks and months. Tells you what your body is capable of at peak readiness.
HRV: your daily recovery status. Changes day to day. Tells you whether your body is ready to push toward that ceiling today.
For complete performance monitoring, you need both: VO2 max to benchmark fitness trends, HRV to make daily training decisions.
Related concepts
- HRV — daily recovery metric; complements VO2 max for complete training picture
- Heart rate zones — VO2 max determines the thresholds that separate the 5 training zones
- Resting heart rate — a secondary cardiorespiratory fitness indicator; lower is generally better
- Active recovery — necessary to allow VO2 max improvements to be absorbed