Liesen Formula

Estimate maximum heart rate (MHR) with the Liesen formula, which lowers the baseline as age increases in decade steps rather than using a single linear slope.

Formula

MHR = 180 − age + floor((age − 20) / 10) × 5

In plain terms: start from 180 − age, then add 5 bpm for each full decade after age 20. Examples:

• Age 25 → 180 − 25 + 0 = 155 bpm
• Age 35 → 180 − 35 + 5 = 150 bpm
• Age 55 → 180 − 55 + 15 = 140 bpm

When to use it

Helpful when you want a conservative MHR estimate that flattens the decline for older adults compared with 220 − age, or when demonstrating piecewise age adjustments in sports-science coursework.

Limitations

The decade bonus is a heuristic; it is less cited in recent meta-analyses than Tanaka or Ball State equations. It does not account for sex, training status, or medication. Individual spread around the estimate can exceed ±15 bpm.

Example

Age 44 under the liesen formula yields a concrete bpm estimate (not a clinical measurement).

This skill is available over A2A JSON-RPC and REST. When you already know the skill id and export, call execute directly—no discovery step required.

REST example

curl -sS -X POST https://toolplaza.app/api/helpers/execute \
  -H 'Content-Type: application/json' \
  -d '{"skillId":"heart__liesen-formula","export":"calculateLiesenMaxHeartRate","args":[10,20]}'

A2A JSON-RPC example

Send POST https://toolplaza.app/api/a2a with:

{
  "jsonrpc": "2.0",
  "id": "1",
  "method": "message/send",
  "params": {
    "message": {
      "messageId": "uuid",
      "role": "user",
      "parts": [
        {
          "kind": "text",
          "text": "ignored"
        }
      ]
    },
    "metadata": {
      "toolplaza": {
        "skillId": "heart__liesen-formula",
        "export": "calculateLiesenMaxHeartRate",
        "args": [
          10,
          20
        ]
      }
    }
  }
}

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