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Running form by the numbers

July 22, 2026 · 6 min read

Running form analysis used to require a gait lab. Now the interesting metrics — the ones coaches and physios actually look at — can be measured from a phone video of you running past the camera. Here's what each number means, what the research says about good ranges, and how to measure yours.

Cadence (steps per minute)

The most-cited running metric. Low cadence usually pairs with overstriding — landing with the foot far ahead of the body, which brakes every step and loads the knees. There's no universal perfect number (it varies with speed and height), but most recreational runners sit in the 160–180 spm range, and a 5% cadence increase is a common, well-tolerated fix for overstriding. Vi.S.In estimates cadence automatically from the rhythm of your footstrikes and shows it in the gait metrics card above the chart.

Ground contact time

How long each foot stays planted, in milliseconds — typically 200–300 ms for recreational runners, shorter as pace and efficiency improve. Left/right differences are the interesting part: a persistent gap can flag an asymmetry worth investigating.

Vertical oscillation

How much your center of mass bounces each stride. "Glide, don't pogo" — energy spent going up doesn't move you forward. Vi.S.In reports it as a percentage of your body height, tracked from your hip center.

Shin angle at footstrike

The classic overstriding check: at the moment of contact, a shin close to vertical means you're landing under your body; a shin angled far forward means braking. In the angle chart, the Lower Leg to Vertical curve reads this directly — its value at each footstrike is your strike-shin angle, and its peak each stride is your maximum shank angle (elite runners reach 11–18°).

Foot angle at contact

Heel striker, midfoot, forefoot? The Foot to Horizontal angle at contact tells you: near 0° is a flat midfoot landing, positive toe-up is a heel strike, toes-down is a forefoot strike. None is universally "correct" — but knowing yours matters when changing shoes or dealing with injury.

Trunk lean and pelvic drop

A slight forward lean (3–10° from vertical, from the ankles rather than a waist bend) is the usual cue; more than ~6° of hip drop on the stance side correlates with IT-band and runner's-knee complaints. Both are in the preset: trunk lean from the side view, pelvic drop if you film from behind.

How to measure yours

1. Film ~10 seconds of running from the side, camera steady (a treadmill or a friend standing still works; a few full strides is enough).
2. Drop it into the analyzer and press Get Poses.
3. The gait metrics card appears automatically with cadence, contact time, and vertical oscillation.
4. Apply the Running (gait) preset for the angle curves — knees, shins, feet, trunk lean — with target bands drawn on the chart.

Then change one thing at a time — a metronome for cadence, a cue for lean — refilm, and Compare the two clips side by side. Numbers make the difference visible while it's still too small to feel.