Figure 1. Symmetrical step lengths (Symmetrical).

The Symmetrical group (n=17) was characterized by equivalent paretic and nonparetic step lengths while walking overground. (a) Spatial and (c) temporal symmetry were calculated with a symmetry index (SI) with the general equation SI =Xp/(Xp+Xnp), where Xp and Xnp are the paretic and nonparetic values for the variable of interest, respectively. Step length and percent of the gait cycle spent in single limb support were used to assess spatial and temporal symmetry. The symmetry index calculated for step length results in the paretic step ratio (PSR) used to categorize asymmetry groups (see Methods). Individual data are illustrated; the vertical black line represents the group median. The vertical gray shaded areas denote the SI values that represent symmetry (0.475 ≤ SI ≤ 0.525).⁷ Box-and-whisker plots for (b) step length and (d) single limb support duration (SLS%) illustrate the distribution of the individual leg data. The whiskers illustrate the 5^th and 95^th percentiles. Group means are depicted with “+”. Paretic and nonparetic leg data are illustrated in grey and black, respectively. Of note, the temporal symmetry achieved in the Symmetrical group with Guidance_NP results from a concurrent nonparetic reduction and paretic increase in SLS%. Abbreviations: OG: overground condition at self-selected walking speed; TM: treadmill condition at self-selected walking speed, with 0% BWS; BWS: body weight support condition at self-selected walking speed, with 30% BWS; Guidance_NP: fastest comfortable walking speed, with 30% BWS, and nonparetic limb guidance.