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*)

- "the
**distance travelled by the trunk while a particular foot is on the ground**." (**R McNeil Alexander**,*Terrestial Locomotion,*in his book,*Mechanics & Energetics of Animal Locomotion, p 171*)

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?

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