Sprint analytics: strides and mechanics
Contact time, flight time, stride length, cadence, shin angle, thigh lift and trunk angle for every stride, against elite sprinter ranges.
Run a straight sprint and scroll down the run summary. Under the Acceleration card, Metric Sprint adds two more: Stride analysis and Sprint mechanics. They break the run down foot strike by foot strike, from the video alone. Every recorded sprint gets them, on every plan.
How Metric Sprint counts a stride
Metric Sprint finds each foot contact from the video. It marks touchdown when your toe stops moving forward with your body, and toe-off when it moves again. A heel that lands first moves touchdown earlier.
In Metric Sprint, a stride runs from one foot strike to the next, so left foot to right foot is one stride. Every stride value belongs to the contact that starts it.
The charts plot one dot per stride against distance down the lane, in metres. Open dots are your left foot and filled dots are your right. Strides in your top-speed zone draw full strength. Strides before it fade, so the top-speed part of the run stands out.
Stride analysis
| On screen | Unit | What it measures |
|---|---|---|
| Contact time | ms | Touchdown to toe-off of one foot contact. |
| Flight | ms | Toe-off to the next touchdown. It shows in the table only. |
| Stride length | m | Distance from one foot plant to the next, along the lane. |
| Cadence | strides per minute | How many foot strikes you would take in a minute at that stride’s rhythm. |
Your speed is stride length × cadence. Stride length grows as you build speed, then levels off.
Under the charts, a table gives the mean of each metric for each section between your gates, such as 0–10 m. An All row covers the whole run. Read the section means first. A single contact time can scatter by a few hundredths of a second. The means smooth that out.
Sprint mechanics
| On screen | When it is measured | What it measures |
|---|---|---|
| Shin angle | At touchdown | The angle of the shin, knee to ankle, from vertical. A positive angle means the ankle lands ahead of the knee. A negative angle means the shin leans forward. |
| Thigh lift | Between touchdowns | The highest angle the swing thigh reaches, hip to knee, from vertical. 90° means the thigh is level with the ground. |
| Trunk angle | At touchdown | The lean of your trunk, pelvis to neck, from vertical. A positive angle means you lean forward. |
On the thigh lift chart, each dot belongs to the swing leg, so a left-foot contact draws a right-thigh dot. The trunk angle chart does not split by foot.
Elite ranges
A green band on each chart shows the range Metric Sprint uses for trained sprinters. The band changes with distance down the lane. It starts at the acceleration range and moves towards the top-speed range, most of the way by 30 m.
- Contact time — about 180 ms off the start, down to 90–140 ms at top speed. The band allows for grass and trainers.
- Cadence — about 240–280 strides per minute through the whole run, from the step frequencies Nagahara et al. (2014) measured in sprinters. Athletes with longer legs sit lower in the band.
- Shin angle — leaning forward early, near vertical only at top speed. The top-speed range follows Miyashiro et al., who measured 79 sprinters at top speed. At touchdown, their ankle landed about 5° ahead of the knee.
- Thigh lift — 65–90° through the whole run.
- Trunk angle — 30–40° of forward lean to 10 m. Then 15–25° from 10 to 30 m, and 0–5° at top speed. These phase ranges come from Athletics Australia coaching material.
A dot outside the band is a place to look in the video, not a fault on its own. Compare each athlete against their own runs first.
Drive phase and top speed
On sprints of 20 m or longer, the Acceleration card marks two points on your speed curve:
- Drive ends — the solid line. It marks two strides in a row where your shin lands vertical or ahead of the knee.
- Top speed — the shaded zone. It starts at the first stride that lands at 90% or more of your peak velocity.
Under the chart, Top speed from gives the distance where that zone starts, and Top-speed strides counts the strides inside it. A 10 m run never stops accelerating, so it gets no phase marks.
See it on the video
Tap the settings button on the run video. Under Overlays, turn on Stride length and Foot contacts. Each contact gets a mark with its side and contact time, for example L 120 ms, and an arc shows each stride length. Use Previous foot contact and Next foot contact to step through the run one stride at a time. The video marks every contact, so it shows contacts that the charts do not plot.
When it goes wrong
- No stride cards on the summary. Metric Sprint shows them on straight sprints only, not on agility tests. They also need at least two gates crossed. A run recorded before Metric Sprint 2.0 may not have the foot data.
- A dash in the table. Metric Sprint could not measure that value for the section.
- Fewer dots than strides. The charts plot clean contacts only. The set stance, a contact with a missed touchdown or toe-off, and contacts after the finish do not plot. If it misses a contact, the stride before it has no length, cadence or flight.