Contribution of Paretic and Nonparetic Limb Peak Propulsive Forces to Changes in Walking Speed in Individuals Poststroke

Abstract

Background: Recent rehabilitation efforts after stroke often focus on increasing walking speed because it is associated with quality of life. For individuals poststroke, propulsive force generated from the paretic limb has been shown to be correlated to walking speed. However, little is known about the relative contribution of the paretic versus the nonparetic propulsive forces to changes in walking speed.

Objective: The primary purpose of this study was to determine the contribution of propulsive force generated from each limb to changes in walking speed during speed modulation within a session and as a result of a 12-week training program.

Methods: Gait analysis was performed as participants (N = 38) with chronic poststroke hemiparesis walked at their self-selected and faster walking speeds on a treadmill before and after a 12-week gait retraining program.

Results: Prior to training, stroke survivors increased nonparetic propulsive forces as the primary mechanism to change walking speed during speed modulation within a session. Following gait training, the paretic limb played a larger role during speed modulation within a session. In addition, the increases in paretic propulsive forces observed following gait training contributed to the increases in the self-selected walking speeds seen following training.

Conclusions: Gait retraining in the chronic phase of stroke recovery facilitates paretic limb neuromotor recovery and reduces the reliance on the nonparetic limb's generation of propulsive force to increase walking speed. These findings support gait rehabilitation efforts directed toward improving the paretic limb's ability to generate propulsive force.

Keywords: gait; ground reaction force; propulsion; stroke; walking speed.

© The Author(s) 2015.

Figures

Figure 1

Illustration of trials and changes among trials studied. “SS” indicates self-selected walking speed trial, and “FS” indicates faster walking speed trial. “Speed modulationpre” was calculated as the change from SS to FS at pre-training, “Speed modulationpost” was calculated as the change from SS to FS at post-training, “Change in SS” was calculated as the change from Pre-SS to Post-SS, and “Change in FS” was calculated as the change from Pre-FS to Post-FS.

Figure 2

Relationships between anterior ground reaction force (AGRF) and walking speed (N=38). (A–D): Pre-training. (E–H): Post-training. “SS” denotes self-selected walking speed and “FS” denotes faster walking speed. “BW” denotes the bodyweight. “†” indicates p

Figure 3

Mean and standard error of propulsive force and walking speeds at self-selected (SS) and faster (FS) walking speeds for pre and post training. Black bars represent data from paretic limb and black bars represent data from non-paretic limb. Anterior ground reaction force (AGRF) was normalized by body weight (BW).

Figure 4

Relationships between changes in anterior ground reaction force (ΔAGRF) and changes in walking speed during speed modulation within a session prior to (Δspeedpre) and following (Δspeedpost) the 12-week training (N=38). “Paretic” denotes the paretic limb. “Non-Paretic” denotes the non-paretic limb. “BW” denotes the bodyweight. “Δ” denotes the difference during speed modulation from SS to FS within a session. “*” indicates p < 0.05 and “†” indicates p < 0.01. (A) Relationship between changes in paretic propulsive force and changes in walking speed at pre-training. (B) Relationship between changes in non-paretic propulsive force and changes in walking speed at pre-training. (C) Relationship between changes in paretic propulsive force and changes in walking speed at post-training. (D) Relationship between changes in non-paretic propulsive force and changes in walking speed at post-training.

Figure 5

Relationships between changes in anterior ground reaction force (ΔAGRF) and changes in self-selected (ΔSS) and faster (ΔFS) walking speed as a result of the 12-week training. “Paretic” denotes the paretic limb. “Non-Paretic” denotes the non-paretic limb. “BW” denotes the bodyweight. “Post-Pre” denotes the difference from pre-training to post-training. “*” indicates p