Output Format

The response is the original input JSON with a result object added, plus an updated memory if fitting was performed.

Core result fields

Field	Type	Description
E	float	Endurance (0–1). Higher = greater aerobic capacity
Vmax	float	Maximum speed (m/s). The absolute top speed this person can achieve
V5	float	Internal speed parameter (m/s). Use Vmax for display and interpretation
P	float	HRmax (bpm). Model-predicted maximum heart rate
confidence	float	Overall confidence (0–1). Product of criteria below
dataQualityCriterion	float	Data quality score (0–1)
fitQualityCriterion	float	Model fit quality (0–1)
intensityCriterion	float	Exercise intensity appropriateness (0.9–1.0)

Bayesian estimates (from memory — use these, not the raw values above):

Field	Type	Description
trueE	float	Bayesian-refined endurance
trueVmax	float	Bayesian-refined maximum speed (m/s)
trueV5	float	Bayesian-refined internal speed parameter
trueP	float	Bayesian-refined HRmax
trueConfidence	float	Accumulated confidence (0–10)

Conditional fields

Field	Condition	Type	Description
prediction	returnPrediction: true	float[]	Predicted HR array, one per data sample
V	fixedSpeed: true	float	V-scale intensity at the test speed
propOfMax	fixedSpeed: true	float	Recovery start / max tolerable duration
stats	returnStats: true	object	Full derived metrics (see Derived Metrics)
errors	returnErrors: true	object	Memory error surface for Bayesian updates

Example response (fit mode)

{
  "result": {
    "E": 0.65,
    "Vmax": 4.71,
    "V5": 4.2,
    "P": 185.0,
    "confidence": 0.82,
    "trueE": 0.64,
    "trueVmax": 4.68,
    "trueV5": 4.18,
    "trueP": 184.0,
    "trueConfidence": 3.5,
    "prediction": [80.0, 82.3, 85.1, ...]
  },
  "memory": {
    "secsSinceEpoch": 1712000000,
    "confidence": 0.82,
    "minKey": "18504265",
    "minValue": 12.5,
    "cutoffValue": 15.0,
    "keys": [18504265, 18504266, ...],
    "errorsX1000": [12500, 13200, ...]
  }
}

Bayesian memory fields

The memory object is returned when fit: true. Pass it back as input for the next session to enable multi-session parameter refinement.

Field	Type	Description
secsSinceEpoch	int	Timestamp of this analysis
confidence	float	Accumulated confidence (0–10 scale)
minKey	string	Best parameter combination key
minValue	float	Lowest error value
cutoffValue	float	Error cutoff for pruning
keys	int[]	Parameter combination keys
errorsX1000	int[]	Errors × 1000 (integer-encoded)

See Bayesian Memory for key encoding and decay mechanics.

Speed unit note

Vmax is returned in m/s. To convert:

• km/h: multiply by 3.6
• mph: multiply by 2.237