Step Length

Why this matters

Step length is the distance half of the speed equation (speed = cadence × step length). It is also the most direct read on over-striding: how far the lead foot has landed ahead of the trailing foot at the instant of contact tells you whether the foot is landing under the body or reaching out in front of it. A foot that lands well ahead of the centre of mass plants a braking force on every step, demands a hard eccentric quad load, and is the textbook mechanism behind patellofemoral pain and a heavy heel strike.

Crucially, step length and cadence trade off against each other. Two runners at identical pace can have very different mechanics — one quick and short, one slow and long — and the long one is usually the one fighting injury. Reading step length alongside Cadence is how you tell an efficient stride from an over-stride at the same speed.

A two-click span, in metres

Mark the clip's scale once, then this is a single two-click drawing: the lead foot contact and the trailing foot contact at the chosen frame. The tool returns the real-world distance between them in metres. Earlier versions asked you to also draw a leg segment to normalise the span into "leg lengths" — that was a workaround for not having a real-world scale. Now that the Scale tool gives the clip an honest pixels-per-metre, the leg reference is redundant and has been removed: one span, straight to metres.

Because it's a within-frame distance, this works on a treadmill where the runner never translates across the screen — the two feet are still separated at contact, and that separation is the proxy for step length.

Calibrating the clip (do this first)

Arm the Scale tool (⟷ in the markup row) and draw a line over any object of known length lying in roughly the same plane as the runner — a shoe (~0.30 m), a floor marking, a track line, a hurdle. Enter its real length and the clip gains a pixels-per-metre scale that persists with the analysis. From then on every Step Length drawing on that clip reads in metres. If you measure step length on a clip that hasn't been calibrated, the tool will prompt you to set the scale rather than store a meaningless pixel count — calibrate once and carry on.

A note on targets: absolute step length has no universal "good" band — it scales with the athlete's leg length and speed — so the figure is reported as a measurement to track and compare within an athlete (left vs right, fresh vs fatigued, this month vs last), not graded against a population range. Pair it with cadence and stride angle to read the mechanics.

What good looks like

A step length consistent with the runner's height and pace, paired with a cadence in the 165–185 band and a lead foot landing close under the hip rather than reaching out ahead. The most informative use is change: a step that grows longer as cadence sags late in a run is the over-stride creeping in with fatigue.

Common faults

• Over-stride — the lead foot reaches well ahead of the body; the metre figure climbs while cadence falls and the stride angle tips far forward. Cross-check Stride Angle and Cadence.
• Collapsing step late in a run — step length shortening alongside a sagging cadence is mechanical fatigue; the runner is conserving energy by shortening the swing.

Coaching cues

• "Land your foot under your knee, not out in front." Combined with a small cadence bump, this is the fastest way to rein in an over-stride.
• Re-measure after a cadence cue — a shorter step is usually a consequence of quicker feet, not a separate thing to chase.

Related measurements

• Cadence — the other half of speed; a long step and a low cadence are the same over-stride seen two ways.
• Stride Angle — over-stride shows here as a far-forward tibia at contact.
• Initial Contact — Knee Flexion — long steps typically land on a stiffer, more extended knee.