VO2max Estimation

FitOps estimates VO2max from your run performance data using a weighted composite of three established formulas.

Why Three Formulas?

Each formula was derived from a different population and methodology. A weighted composite is more robust than any single estimate.

Formula	Weight	Basis
VDOT (Daniels)	50%	Pace-based; widely used in competitive running
McArdle	30%	Distance + time on a fixed protocol
Costill	20–40%	Speed-based field estimate

The final estimate is a weighted average, and the spread between individual estimates determines a confidence level.

Confidence Score

Label	Meaning
High	All three methods agree closely
Medium	Two methods agree; one is an outlier
Low	Estimates vary widely — more data needed

What Counts as a Qualifying Activity?

• Sport type: Run or TrailRun
• Distance: at least 1500m
• The most recent qualifying activity is used as the primary estimate source

Limitations

• VO2max is a physiological measurement. This is an estimate from field performance — not a lab value.
• Heat, altitude, fatigue, and pacing strategy all affect the estimate.
• For best accuracy, use a recent race or time trial where you ran close to maximal effort.

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Age Adjustment

VO2max naturally declines with age. The --age-adjusted flag applies a correction factor to account for this.

fitops analytics vo2max --age-adjusted

Methodology

The adjustment uses a linear decline model anchored at age 25:

age_factor = max(0.5, 1.0 − (age − 25) × 0.008)
adjusted_estimate = raw_estimate × age_factor

Key properties:

• At age 25, the factor is exactly 1.0 (no adjustment)
• Each year above 25 reduces the factor by 0.8%
• The factor is floored at 0.5 to avoid unrealistic values for very old ages
• Athletes younger than 25 receive a factor above 1.0 (reflects higher typical VO2max in youth)

Example

Age	Factor	Raw 50.0 → Adjusted
20	1.040	52.0
25	1.000	50.0
35	0.920	46.0
45	0.840	42.0
60	0.720	36.0

Requirement

Age adjustment requires the athlete's birthday to be stored in the local database. Strava includes birthday in the athlete profile, so running fitops sync run once should populate it automatically.

If the birthday is not available, the output includes an error message in the age_adjusted field and the raw estimate is still returned.

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Command

fitops analytics vo2max
fitops analytics vo2max --activities 20    # consider more recent runs
fitops analytics vo2max --age-adjusted     # include age-adjusted estimate

See Output Examples → Analytics for the VO2max JSON response.

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