Vector coding: A technique for quantification of intersegmental coupling in multicyclic behaviors

The evaluation of a vector coding technique to quantify intersegmental coup ling within a limb over multiple cycles of walking is described. The angula r position of the knee with respect to the hip during walking was examined based on relative motion plots generated from videographic data. Participan ts included one able-bodied individual and one with spinal cord injury; the latter was assessed before and after participating in an assisted walking program. Vector coding of the frame-to-frame changes in hip/knee relationsh ip was used to quantify the relative motion plots. Vector analysis techniqu es were then used to produce a single value that represents the overall var iability of the hip/knee coupling relationship over multiple cycles. Hypoth etical and random data were also used to evaluate the coding algorithm. In addition, the technique was compared to an earlier method in the analysis o f this same data. Vector coding provided an easily interpretable method of quantifying the intersegmental coupling relationships and assessing the deg ree of consistency in the intralimb coordination over multiple cycles. The measure is sensitive to change in the kinematic variables and appears to ha ve good validity. In addition, this technique has advantages over prior tec hniques as it allows simultaneous comparison of multiple cycles, calculatio ns are performed quickly, and the algorithm is easy to program.