Understanding Your VO2 Max

VO2 Max: What Cyclists Need to Know

VO2 max discussions have gotten complicated with all the fitness trackers and training science flying around. As someone who became mildly obsessed with watching my Garmin estimate change day to day, I learned everything there is to know about what this number actually means. Today, I’ll share the practical reality.

What It Actually Measures

Probably should have led with this section, honestly. VO2 max is the maximum amount of oxygen your body can use during intense exercise. Higher number means your cardiovascular system delivers more oxygen to muscles, which means you can sustain higher intensity longer.

Measured in milliliters of oxygen per kilogram of body weight per minute (ml/kg/min). The “per kilogram” part normalizes for body size.

What’s a Good Number?

Average untrained adult: 35-45 ml/kg/min

Regular recreational cyclist: 45-55 ml/kg/min

Competitive amateur: 55-65 ml/kg/min

Elite endurance athlete: 65-80+ ml/kg/min

Professional Tour riders often measure in the 80s. For most of us, getting into the 50s represents good fitness. Getting into the 60s requires serious training.

How It’s Measured

That’s what makes lab testing endearing to us data nerds — true VO2 max testing involves riding or running at increasing intensity while wearing a mask that measures oxygen consumption. They push you to absolute failure.

Smartwatches estimate VO2 max using heart rate and pace/power algorithms. Reasonably accurate for tracking trends, but the absolute number might be off by 5-10% from a lab test.

What Affects Your VO2 Max

Genetics: About 50% of your potential is genetic. Some people have higher ceilings.

Training: Consistent aerobic exercise raises it. High-intensity intervals are particularly effective.

Age: Naturally declines about 1% per year after your 20s. Training slows but doesn’t stop this.

Body composition: Extra fat lowers your relative VO2 max without necessarily changing absolute oxygen consumption.

Improving Your Number

Interval training: 3-5 minute intervals at 90-100% of max heart rate with equal recovery.

Threshold work: Sustained efforts at the highest intensity you can maintain for 20-30 minutes.

Long endurance rides: Build base fitness that allows harder interval work.

Consistency matters more than any single workout.

It’s Not the Only Thing

Other factors determine cycling performance:

Lactate threshold: The intensity where lactate accumulates faster than you can clear it.

Efficiency: How effectively you convert oxygen into power at the pedals.

Fatigue resistance: How well you maintain performance over hours.

A rider with lower VO2 max but better efficiency and threshold can outperform someone with a higher number.

Using the Data

Watch the trend over time rather than fixating on the absolute number. If your estimated VO2 max is rising over months of training, you’re improving. If it’s flat or dropping, something needs adjustment.

Comparing yourself to professional athletes is pointless. Compare yourself to yourself three months ago.

Health Beyond Performance

VO2 max correlates strongly with longevity and overall health. Higher cardiovascular fitness reduces risk of heart disease, diabetes, and all-cause mortality.

Even if you don’t care about performance, improving VO2 max through any exercise is one of the best things you can do for long-term health.