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

instrument implementation / implementation-contract

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

A source-bound implementation contract for VO2max Estimator (non-exercise / walk test); deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t4-218

**Effect**: Computation or source lookup only

## Input and validation requirements

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.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "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"
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/vo2max-estimator-non-exercise-walk-test/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/vo2max-estimator-non-exercise-walk-test/mechanism/>)[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`