Heart Rate Zone Calculator implementation

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

t4-223

Effect

Computation or source lookup only

Input and validation requirements

An extreme but syntactically numeric age such as 1e308 can produce a finite negative HRmax and entirely negative zone values instead of being rejected. Age zero is also accepted arithmetically despite being an invalid real-world demographic input.

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": {
    "age_years": 30,
    "method": "percent_HRmax",
    "resting_HR_bpm": null
  },
  "expected_outputs": {
    "HRmax_bpm": 190,
    "zones_bpm": [
      {
        "zone": "50-60%",
        "range": "95 to <114"
      },
      {
        "zone": "60-70%",
        "range": "114 to <133"
      },
      {
        "zone": "70-80%",
        "range": "133 to <152"
      },
      {
        "zone": "80-90%",
        "range": "152 to <171"
      },
      {
        "zone": "90-100%",
        "range": "171 to 190 inclusive"
      }
    ]
  },
  "working": "HRmax = 220 − 30 = 190 bpm. Zone boundaries: 190×0.50 = 95; 190×0.60 = 114; 190×0.70 = 133; 190×0.80 = 152; 190×0.90 = 171; 190×1.00 = 190. Therefore the five intervals are [95,114), [114,133), [133,152), [152,171), and [171,190]."
}

Other records

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