Measurement scales

When rendering a gauge or scale for biomechanical measurements, you need to know the overall min/max boundaries of the scale in addition to the range_good and range_okay values returned by the API. This guide documents the fixed scale boundaries for every measurement type so you can render consistent visualizations regardless of the runner’s measured value.

How scoring ranges work

Each biomechanical measurement in the API response includes:

Field	Description
`measured_value`	The actual measured angle (in degrees)
`score_number`	Normalized score between 0 and 1
`range_good`	`[min, max]` — values within this range score highest
`range_okay`	`[min, max]` — values within this range score moderately
`range_bad`	`[min, max]` — (back view only) values outside okay, scoring lowest

All range values are expressed in degrees. Range boundaries can overlap — see analysis workflow for inclusion/exclusion rules.

Back view — fixed scale boundaries

Back-view measurements use fixed ranges that do not change based on athlete morphology. The API returns range_bad for back-view segments — use it as the overall scale boundary.

Pelvic drop (per side)

Field	Value	Unit
`range_good`	`[0, 2]`	degrees
`range_okay`	`[2, 4]`	degrees
`range_bad`	`[4, 8]`	degrees
Scale min	0	degrees
Scale max	8	degrees

range_bad[1] (8°) is the scale maximum. Display the gauge from 0 to 8.

Pronation / supination (per side)

Field	Value	Unit
`range_good`	`[-5, 5]`	degrees
`range_okay`	`[-10, 10]`	degrees
`range_bad`	`[-20, 20]`	degrees
Scale min	-20	degrees
Scale max	20	degrees

Negative values indicate pronation (foot rolling inward), positive values indicate supination (foot rolling outward).

Knee adduction (per side)

Field	Value	Unit
`range_good`	`[-3, 3]`	degrees
`range_okay`	`[-5, 5]`	degrees
`range_bad`	`[-10, 10]`	degrees
Scale min	-10	degrees
Scale max	10	degrees

Negative values indicate adduction (knee inward), positive values indicate abduction (knee outward).

Back view summary

Pelvic drop:       |====GOOD====|==OKAY==|=====BAD=====|
                   0           2        4             8

Pronation:    |===BAD===|==OK==|===GOOD===|==OK==|===BAD===|
             -20      -10     -5         5      10        20

Knee add.:    |===BAD===|=OK=|==GOOD==|=OK=|===BAD===|
             -10       -5   -3       3    5        10

Side view — personalized scale boundaries

Side-view ranges are personalized based on the runner’s height, weight, and pace. The range_good and range_okay values returned by the API vary between analyses.

The API does not return range_bad for side-view measurements. Use the recommended display ranges below to render consistent gauges.

Recommended display ranges

Use these fixed boundaries when rendering side-view gauges. They accommodate the full range of personalized values the API can return:

Measurement	Scale min	Scale max	Unit	Notes
Head	`range_okay[0] - 10`	`range_okay[1] + 10`	degrees	Negative = looking down, positive = looking up
Trunk (back)	`range_okay[0] - 10`	`range_okay[1] + 10`	degrees	Forward lean angle
Arm	`range_okay[0] - 10`	`range_okay[1] + 10`	degrees	Elbow angle
Front knee	`range_okay[0] - 10`	`180`	degrees	Knee extension at foot landing
Back knee	`0`	`range_okay[1] + 10`	degrees	Knee flexion (heel kick)
Foot (overstride)	`-10`	`20`	degrees / %	Overstride angle relative to center of gravity

The formula range_okay[0] - 10 / range_okay[1] + 10 provides a safe margin around any measured value while keeping the scale readable.

Foot / overstride (fixed)

Unlike other side-view segments, foot/overstride uses fixed ranges regardless of athlete morphology:

Overground
Treadmill

Field	Value
`range_good`	`[-10, 5]`
`range_okay`	`[5, 10]`
Scale min	-10
Scale max	20

Field	Value
`range_good`	`[-10, 10]`
`range_okay`	`[10, 20]`
Scale min	-10
Scale max	30

Negative values mean the foot lands behind the center of gravity (good). Positive values indicate overstride (foot landing ahead of the center of gravity).

Side view — typical range examples

These are examples of actual API responses for a 1.75m / 70kg runner at 5:00 min/km pace:

Measurement	`range_good`	`range_okay`	Recommended scale
Head	`[-14, -4]`	`[-18, 0]`	`[-28, 10]`
Trunk	`[6, 12]`	`[2, 16]`	`[-8, 26]`
Arm	`[75, 85]`	`[71, 89]`	`[61, 99]`
Front knee	`[145, 180]`	`[136, 145]`	`[126, 180]`
Back knee	`[0, 97]`	`[97, 106]`	`[0, 116]`
Foot	`[-10, 5]`	`[5, 10]`	`[-10, 20]`

Side-view ranges change with athlete morphology. The values above are illustrative — always compute your scale boundaries from the actual range_okay values returned per analysis.

Implementation example

function getScaleBounds(segment, analysisType) {
  // Back view: use range_bad directly
  if (analysisType === 'back_view') {
    return {
      min: segment.range_bad[0],
      max: segment.range_bad[1],
    };
  }

  // Side view foot: fixed scale
  if (segment.texts?.search_key?.startsWith('Midfoot') ||
      segment.texts?.search_key?.startsWith('Rearfoot') ||
      segment.texts?.search_key?.startsWith('Forefoot')) {
    return { min: -10, max: 20 };
  }

  // Side view forward_cycle: lower bound from range_okay, upper bound is 180
  if (segment.texts?.title === 'Front knee angle at foot landing') {
    return {
      min: segment.range_okay[0] - 10,
      max: 180,
    };
  }

  // Side view back_cycle: lower bound is 0, upper bound from range_okay
  if (segment.texts?.title === 'Back knee angle at foot landing') {
    return {
      min: 0,
      max: segment.range_okay[1] + 10,
    };
  }

  // Side view head, trunk, arm: ±10 from range_okay
  return {
    min: segment.range_okay[0] - 10,
    max: segment.range_okay[1] + 10,
  };
}

Score interpretation

The score_number field (0 to 1) indicates how well the measured value falls within the ideal range:

Score range	Interpretation
0.7 — 1.0	Good — within or very near `range_good`
0.4 — 0.7	Okay — within `range_okay`
0.0 — 0.4	Needs improvement — outside `range_okay`

The overall total_score for side view is a weighted combination of segment scores, not a simple average.

Getting started

Guides

How scoring ranges work

Back view — fixed scale boundaries

Pelvic drop (per side)

Pronation / supination (per side)

Knee adduction (per side)

Back view summary

Side view — personalized scale boundaries

Recommended display ranges

Foot / overstride (fixed)

Side view — typical range examples

Implementation example

Score interpretation

​How scoring ranges work

​Back view — fixed scale boundaries

​Pelvic drop (per side)

​Pronation / supination (per side)

​Knee adduction (per side)

​Back view summary

​Side view — personalized scale boundaries

​Recommended display ranges

​Foot / overstride (fixed)

​Side view — typical range examples

​Implementation example

​Score interpretation

How scoring ranges work

Back view — fixed scale boundaries

Pelvic drop (per side)

Pronation / supination (per side)

Knee adduction (per side)

Back view summary

Side view — personalized scale boundaries

Recommended display ranges

Foot / overstride (fixed)

Side view — typical range examples

Implementation example

Score interpretation