Source: https://guthlabs.ai/docs/instruments/vo2max-estimator-non-exercise-walk-test/mechanism/

instrument mechanism / verified-clean

# VO2max Estimator (non-exercise / walk test) mechanism

The inspectable method record for VO2max Estimator (non-exercise / walk test), kept separate from implementation and qualification.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Model scope

The honest-label text is appropriate and should be retained: this is a population-regression or walk-test estimate, not medical advice. Final formula verification requires the exact regression coefficients, Rockport variant, input encodings, validation ranges, method-selection rule, and fitness-norm table.

- The specification names a non-exercise regression and a Rockport walk-test formula but provides no coefficients, so the implemented formula cannot be verified.

- The non-exercise method is ambiguous: a standard candidate is VO2max = 50.513 + 1.589×sex − 0.289×age − 0.552×BMI + 5.863×activity, but sex coding and the activity-rating scale are unspecified.

- The Rockport method is ambiguous because multiple published variants exist; a standard candidate is VO2max = 132.853 − 0.0769×weight(lb) − 0.3877×age + 6.315×sex − 3.2649×walk_time(min) − 0.1565×heart_rate(bpm).

- The selection rule between the non-exercise regression and walk-test formula is unspecified.

- Fitness-category output cannot be verified because the age/sex norm table, category boundaries, source, and handling of values between age bands are not provided.

- The sex input is underspecified for both formulas: the candidate formulas use binary coding, but supported values and handling of nonbinary, unknown, or undisclosed sex are not defined.

## Units and conventions

- The candidate non-exercise formula assumes age in years, BMI in kg/m², activity as the original dimensionless physical-activity rating, and sex coded male=1 and female=0.

- The candidate Rockport formula assumes body weight in pounds, age in years, one-mile walk time in minutes, post-walk heart rate in beats per minute, and sex coded male=1 and female=0.

- If weight is collected in kilograms, it must be converted using 1 kg = 2.20462 lb before applying the candidate Rockport formula.

- The VO2max output unit is mL/kg/min; the formulas do not produce absolute oxygen consumption in L/min.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "formula_variant": "non-exercise candidate regression",
    "age_years": 30,
    "sex_code": 1,
    "BMI_kg_per_m2": 24,
    "activity_rating": 3
  },
  "expected_outputs": {
    "VO2max_mL_per_kg_per_min": 47.773
  },
  "working": "VO2max = 50.513 + 1.589×1 − 0.289×30 − 0.552×24 + 5.863×3\n= 50.513 + 1.589 − 8.670 − 13.248 + 17.589\n= 47.773 mL/kg/min"
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

Exact-zero inputs yield a plausible-looking raw number despite being physiologically invalid, and an extreme walk-time input overflows to -Infinity unless range validation is applied. The specification also omits explicit coefficient, unit, validity-range, and category-table definitions.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/vo2max-estimator-non-exercise-walk-test/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/vo2max-estimator-non-exercise-walk-test/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/vo2max-estimator-non-exercise-walk-test/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche4/tranche4-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`