What we measure
Eleven measurements.
Stride returns eleven biomechanical measurements from a single sprint video. Each is defined below in general terms. Every result also carries a confidence level, and Stride only turns results it trusts into coaching advice.
Ground contact time
secondsThe interval between the foot touching the ground and leaving it, measured for a single foot.
Flight time
secondsThe interval between toe-off of one foot and touchdown of the opposite foot, when neither is in contact with the ground.
Step frequency
steps per secondThe number of ground contacts made per second, counting both feet.
Step length
metresThe horizontal distance travelled between one foot’s touchdown and the opposite foot’s touchdown.
Touchdown distance
metresThe horizontal distance between the foot at touchdown and the athlete’s centre of mass. This is the measurement behind the word overstriding.
Hip extension at toe-off
degreesThe angle between the trunk and the thigh at the instant the foot leaves the ground.
Knee drive
degreesThe peak hip flexion angle reached by the front-side thigh during the swing phase.
Trunk lean
degreesThe forward inclination of the torso from vertical, measured hip to shoulder.
Shin angle at touchdown
degreesThe angle of the lower leg relative to vertical at the instant of ground contact.
Vertical oscillation
centimetresThe vertical displacement of the centre of mass between its lowest point in contact and its highest in flight.
Left–right symmetry
percent differenceThe percentage difference between the left and right legs on contact time, flight time and step length within the same run.
Why eleven and not more
A longer list is easy to produce and harder to act on. These are the measurements that change what a sprinter does in their next session, reported against the phase of the run they were taken in rather than averaged across it.
The phases themselves are covered under the five phases of a sprint, and the guides cover how to get footage worth measuring.