Running Analyzer
What a phone camera can honestly measure
The Running Analyzer watches your run through your phone's camera and coaches your form live. Camera-based gait analysis is genuinely good — and genuinely limited. This page is the full accuracy sheet: what Kaizen Life measures, how, and where the honest edges are. The same tiers drive the product itself — every number is confidence-gated, and what a camera angle cannot see is never shown as if it could.
How it works
Prop up your phone
Side-on to the treadmill for stride mechanics, or directly behind for hips and arms. A live framing check confirms your whole body is tracked before you start.
On-device motion capture
A 33-point pose model runs on your phone at up to 60 frames per second. No video leaves your device during the run — the analysis happens where the camera is.
A voice in your ear
Your assistant persona coaches from the live numbers: one short cue when something is worth changing, praise when you change it, silence otherwise.
The morning-after report
Every session ends with a written report — evidence with timestamps, drills, and progress against your previous runs. Numbers come from the analysis; the model never invents them.
The accuracy tiers
Published research puts monocular video within 1–3% of lab motion capture on timing metrics and within 3–8 degrees on joint angles. That splits cleanly into three tiers — and the product treats them differently.
Excellent — lab-agreeing
Timing and rhythm. These are the numbers we coach on hardest, because they are the ones the camera nails.
| Metric | How it is measured | Honest note |
|---|---|---|
| Cadence | Foot-strike detection from ankle motion | ±1–2 steps per minute; cross-checkable against your watch |
| Left/right symmetry | Per-stride timing, each foot separately | Timing asymmetry is among the strongest camera signals |
| Vertical oscillation | Hip motion, scaled by your own leg length | Relative measure — camera distance cancels out |
| Trunk lean | Shoulder-to-hip line against vertical (side view) | Robust; requires a true side-on camera |
| Overstride | Shin angle at the moment of foot strike (side view) | The classic side-view catch, well validated |
Good — trend-grade
Angles and stride shape: within a few degrees of lab systems. Excellent for trends across sessions; small single-session differences are noise, and the reports say so.
| Metric | How it is measured | Honest note |
|---|---|---|
| Knee drive | Peak thigh elevation during the swing (side view) | ±3–5°; judged against your declared speed |
| Heel lift | Peak heel rise, scaled by leg length (side view) | Tracked from dedicated heel landmarks |
| Foot-strike pattern | Foot inclination at landing: heel, mid, forefoot (side view) | Needs 60 fps to be trustworthy; flagged when lower |
| Ground contact time | Frames between landing and toe-off (side view) | Reported only above ~40 fps — below that it is withheld, not guessed |
Situational — needs the right camera angle
Frontal-plane events are edge-on from the side — invisible by geometry, not by software. The rear-view session mode exists exactly for these.
| Metric | How it is measured | Honest note |
|---|---|---|
| Pelvic drop | Hip-line tilt at midstance (rear view only) | A side camera cannot see this at all; the rear mode measures it directly |
| Arm crossover | Wrists crossing the body midline (rear view only) | Reported as the share of your stride spent crossed over |
| Running economy | Not measurable from video — economy is metabolic | We do not report an economy score, because a camera cannot know one |
The rules the product runs on
- Every metric carries a confidence score from how well you were tracked — low-confidence numbers are shown greyed, or not at all.
- What a camera angle cannot see is reported as absent, never estimated.
- Analysis runs on your device; your video uploads only when you save, into private storage only you can access.
- Reports cite only computed numbers — the writing model is forbidden from inventing metrics.
- No injury diagnoses. Persistent pain or asymmetry gets one recommendation: a professional gait assessment.
The Running Analyzer is an add-on you can put on any plan.
See pricing