curl --request POST \
  --url https://api.iotools.cloud/v1/tool/vo2-max-estimator-calculator \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "testMethod": "cooper",
  "age": "30",
  "sex": "male",
  "restingHr": "60",
  "cooperDistance": "2400"
}
'

{
  "tool": "vo2-max-estimator-calculator",
  "tool_version": "1.0.1",
  "outputs": {
    "summary": [
      {
        "metric": "VO₂ Max",
        "value": "42.4 ml/kg/min"
      },
      {
        "metric": "Fitness Category",
        "value": "Good"
      },
      {
        "metric": "Test Method",
        "value": "Cooper 12-minute run"
      },
      {
        "metric": "Age Group",
        "value": "30–39"
      },
      {
        "metric": "Sex",
        "value": "Male"
      }
    ],
    "norms": [
      {
        "age": "20–29",
        "poor": "0–37",
        "fair": "38–43",
        "good": "44–51",
        "excellent": "52–56",
        "superior": "57+"
      },
      {
        "age": "30–39",
        "poor": "0–33",
        "fair": "34–39",
        "good": "40–47 (you)",
        "excellent": "48–51",
        "superior": "52+"
      },
      {
        "age": "40–49",
        "poor": "0–29",
        "fair": "30–35",
        "good": "36–43",
        "excellent": "44–47",
        "superior": "48+"
      },
      {
        "age": "50–59",
        "poor": "0–24",
        "fair": "25–31",
        "good": "32–39",
        "excellent": "40–43",
        "superior": "44+"
      },
      {
        "age": "60+",
        "poor": "0–20",
        "fair": "21–26",
        "good": "27–35",
        "excellent": "36–39",
        "superior": "40+"
      }
    ],
    "zones": [
      {
        "zone": "Zone 1 — Very Light",
        "intensity-of-max-hr": "50–60%",
        "bpm-range": "124–136 BPM",
        "training-purpose": "Recovery, warm-up, cool-down"
      },
      {
        "zone": "Zone 2 — Light",
        "intensity-of-max-hr": "60–70%",
        "bpm-range": "136–149 BPM",
        "training-purpose": "Fat burn, base endurance"
      },
      {
        "zone": "Zone 3 — Moderate",
        "intensity-of-max-hr": "70–80%",
        "bpm-range": "149–162 BPM",
        "training-purpose": "Aerobic capacity, stamina"
      },
      {
        "zone": "Zone 4 — Hard",
        "intensity-of-max-hr": "80–90%",
        "bpm-range": "162–174 BPM",
        "training-purpose": "Lactate threshold, speed"
      },
      {
        "zone": "Zone 5 — Maximum",
        "intensity-of-max-hr": "90–100%",
        "bpm-range": "174–187 BPM",
        "training-purpose": "VO₂ max, peak power"
      }
    ],
    "interpretation": "A VO₂ max of 42.4 ml/kg/min is above average for your age group (male, age 30). Based on the Cooper 12-minute run.\n\nTraining tip: Mix two Zone 2 base sessions with one VO₂-max interval workout and one tempo session each week to keep improving.\n\nEstimated values are not a substitute for a graded exercise test in a clinical setting. Consult a physician before starting a new exercise programme."
  },
  "credits_used": 3,
  "credits_remaining": null
}