Spanning set may not be appropriate for measuring knee kinematic variability for the entire gait cycle during...

This study aimed to 1) determine the suitability of using spanning set (SS) to measure knee angle variability in the entire gait cycle and 2) assess the sensitivity of SS magnitude to the order of polynomial fitted to the standard deviation (SD) curves of the mean ensemble curves. Eight runners performed 10 over-ground barefoot running trials, followed by 8 min of accommodation, and then another 10 trials. Knee angle variabilities before and after accommodation were assessed using the SS and two conventional methods: mean coefficient of variation and mean SD. The sensitivity of the SS magnitude was assessed by calculating SS using (n-2), (n-1), (n+1), and (n+2)th orders of polynomials, where nth is the best fit order. Variability decreased after accommodation using the conventional methods (p < .05) but not the SS. The SS magnitude was sensitive to the order of polynomial. It is concluded that the SS may not be appropriate for measuring knee kinematic variability in the entire gait cycle during over-ground barefoot running.