Ground contact time is the duration of a single foot contact, measured from the first frame in which the foot touches the ground to the last frame before it leaves. In running it corresponds to the stance phase of each step. In jumping and plyometrics it is the time spent on the ground between landing and the next takeoff.
Typical Values
Contact time shortens as running speed increases. Recreational distance runners commonly fall somewhere around 200 to 300 milliseconds per contact, while elite sprinters at maximal speed are often near or below 100 milliseconds. Values depend strongly on speed, so comparisons are most meaningful at similar speeds.
Why It Is Measured
- To describe running speed and running style
- To compare left and right contact times for asymmetry
- To assess reactive ability in drop jumps and hops, often alongside flight time
- To monitor changes with fatigue, footwear, or technique work
The reactive strength index, used in plyometric testing, divides jump height or flight time by ground contact time.
Measuring It on Video
- Use a side view at ground level, with the camera perpendicular to the direction of travel
- Mark the touchdown frame and toe-off frame, count the frames between them, and divide by the frame rate
- At 30 fps each frame is about 33 milliseconds, which is too coarse for most running contacts
- At 240 fps each frame is about 4 milliseconds, which is far more useful for running and jumping
- A fast shutter speed makes the exact moment of contact and toe-off easier to judge
Common Pitfalls
- Touchdown and toe-off are often ambiguous by a frame or two, especially with soft surfaces or poor lighting
- Slow-motion clips must be timed using the original capture frame rate, not playback speed
- Treadmill and overground running can produce different contact times
- Shorter contact is not automatically better; it reflects speed and strategy
Frame-by-frame playback with a timer or stopwatch, such as the stopwatch tool in KineVision, makes it practical to measure contact times consistently from high-frame-rate video.