The following exercise explains how you can calculate the stride length and stride frequency of a runner on a treadmill.

Consider first some definitions of terms:

Stride length: Stride Length corresponds to the horizontal distance between the location of a foot at one point in time (usually the first point of contact with the ground)to the same point of the same foot at the next occurrence of the selected position in the running cycle.

Step: A step corresponds to the horizontal distance between the location of a foot at one point in time (usually the first point of contact with the ground) to the same point of the contra-lateral foot at the next occurrence of the selected position in the running cycle. In essence two steps constitute a stride.

Stride Frequency: Stride frequency corresponds to the number of strides that are completed in a specified time period. The standard unit of measurement is the hertz (Hz) which records the number of cycles per second. Step frequency is the equivalent measure using a step (as defined above) as the core parameter.

Timecode: Time code records the passage of time via the use of a sequence of pairs of numbers separated by colons. e.g. 00:01:15:32. The first pair of numbers represents the number of hours, the second pair the number of minutes, the third pair the number of seconds and the last pair the number of hundredths of a second.

The speed of a runner can be defined as being equal to Stride Length × Stride Frequency

Given the relationship between running velocity, stride length and stride frequency plus a video record (with timecode) of a runner on a treadmill it is a straight forward matter to calculate values for the stride length and stride frequency of a runner at a known speed.