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Karvonen API

Provide precision target BPM guidance for cardio sessions with reserve-based intensity control.

Endpoint

  • GET /api/v1/karvonen
  • POST /api/v1/karvonen/post

Parameters

Name Type Required In Description
age integer (>0) Yes Query/Body Age in years.
rhr integer (>0) Yes Query/Body Resting heart rate in bpm.
intensity number (10-100) Yes Query/Body Target workout intensity percentage.
mhr integer (>0) No Query/Body Max HR; if omitted, API uses 220 - age.
lang string No Query Response language (en,es,de,fr,pt,ja,hi,ar).

Why Use This Endpoint

  • Use reserve-based heart-rate targets instead of generic zones.
  • Adjust session design for recovery, aerobic, threshold, and HIIT bands.
  • Add transparent target zone math to consumer cardio apps.

Get Started

Request Example

curl -X GET "https://api.hefitapi.com/api/v1/karvonen?age=35&rhr=58&intensity=72&lang=en" \
  -H "X-API-Key: YOUR_API_KEY"

curl -X POST "https://api.hefitapi.com/api/v1/karvonen/post?lang=en" \
  -H "Content-Type: application/json" \
  -H "X-API-Key: YOUR_API_KEY" \
  -d '{"age":35,"rhr":58,"mhr":188,"intensity":78}'

Response Example

Info

The response example below is for demonstration purposes only. Make a live request to this endpoint to receive the full, real-time, and potentially richer JSON structure.

{
  "age": 35,
  "resting_heart_rate_bpm": 58,
  "maximum_heart_rate_bpm": 185,
  "used_default_max_hr": true,
  "heart_rate_reserve_bpm": 127,
  "intensity_percent": 72.0,
  "target_heart_rate_bpm": 149.44,
  "training_zone_range_bpm": {
    "min": 143.09,
    "max": 155.79
  },
  "intensity_band": "aerobic",
  "intensity_band_label": "Aerobic",
  "risk_signal": "Sustainable zone for base-building sessions.",
  "action_plan": ["Use longer steady-state intervals"],
  "monitoring_plan": "Track drift and perceived exertion each session.",
  "_enterprise": {
    "client": "Acme Health",
    "plan": "pro",
    "request_id": "dd67b47d2223915c",
    "quota": 120,
    "usage_tracking": true
  },
  "_api_metadata_": {
    "endpoint_name": "karvonen",
    "response_language": "en"
  }
}

Product Positioning

Excellent for endurance apps, coaching dashboards, and gym platforms requiring repeatable target BPM automation.

Note

If mhr is omitted, max heart rate defaults to 220 - age.