Teach-in '98

Step & Stride Length

Most computerised motion analysis systems provide a printout of the general gait measures, which includes step and stride lengths. For example, here's the report for the last Case of the Week:

Notice that the right and left step lengths are quite different: the right is 43.3 cm, while the left is 36.1 cm.

Look at the following definitions:

• "the stride length is the distance between two successive placements of the same foot. It consists of two step lengths, left and right, each of which is the distance by which the named foot moves forward in front of the other one. In pathological gait, it is perfectly possible for the two step lengths to be different. If the left foot is moved forward to take a step, and the right one is brought up beside it, rather than in front of it, the right step length will be zero....However, the stride length measured between successive positions of the left foot must always be the same as that measured from the right foot, unless the subject is walking around a curve." (Mike Whittle, Gait Analysis)
• "stride length is the horizontal distance covered along the plane of progression during one stride; it is the distance covered from IC to IC of the same foot... equal to the sum of the two step lengths and will be equal for left and right limbs if the person is walking in a straight line, even in the prescence of marked assymetry... Specific step lengths for right and left side must be measured within the same stride. The term can also be used to specify an average step length over many strides." (David Winter, The Biomechanics & Motor Control of Human Gait)

None of these definitions (by very respected researchers in the field), of a fundamental and seemingly trivial gait parameter, seem to agree!

Questions

• Can the right and left sides of the body really travel different distances and still remain joined together?
• What are the correct definitions of step & stride length?
• What is the significance of different step lengths in a gait report?