Neurodynamics under Different Walking Speeds in Individuals with Chronic Post-Stroke Hemiparesis

Background and Purpose: Stroke is the leading cause of long-term disability in adults worldwide. The ability to return to walking is often a main goal of rehabilitation in individuals with chronic post-stroke hemiparesis. To increase walking speed, non-neurologically impaired individuals produce greater ankle propulsion force at push-off with greater ankle dorsiflexion angles in swing phase with no change in ankle muscle co-contraction index in the swing phase. It remains unclear if individuals post-stroke would adopt similar neuromuscular strategies. Therefore, our aim was to examine the effect of altered walking speeds on propulsion force at push-off, ankle dorsiflexion angle during swing, and co-contraction of the lower leg musculature in individuals with chronic post-stroke hemiparesis. Subjects: We recruited 7 participants with chronic post-stroke hemiparesis and 7 age-similar, non-neurologically impaired controls. Inclusion criteria were 1) \u3e 6 months post stroke with hemiparesis, 2) able to walk without an assistive device for 2 minutes, and 3) able to follow cues and adhere to instructions. Exclusion criteria were 1) had a history of cerebellar stroke(s) and/or 2) unable to walk without an assistive device for more than 2 minutes. Methods: All subjects were tested under three different walking speed conditions: self-selected walking speed (SSWS), fast walking speed (FWS), and slow walking speed (SWS). We examined the propulsion force at push-off, ankle dorsiflexion angle during swing phase, and co-contraction index of the tibialis anterior and gastrocnemius muscles during stance and swing phases. A 2-factor mixed factorial ANOVA was used to assess each variable between leg and the speed condition (FWS, SSWS, SWS). The legs examined were the paretic limb of participants post-stroke, the non-paretic limb of participants post-stroke, and the non-impaired limb of non-neurologically impaired controls. Results: The ANOVA and post-hoc analyses revealed that there were significant increases in ankle dorsiflexion angle during swing phase and propulsion force at push-off in the FWS (4.6±4.3° and -1.1±0.6 N/kg respectively) condition when compared to the SSWS (5.6±4.8° and -0.9±0.5 N/kg respectively) and SWS (5.3±4.6° and -0.7±0.4 N/kg respectively) conditions across the 3 limbs examined. Additionally, the speed and limb had no main effect (p=0.233 and p=0.554 respectively) on co-contraction index between the tibialis anterior and gastrocnemius at peak dorsiflexion during swing and had a trending main effect (p=0.082) on co-contraction index between the tibialis anterior and gastrocnemius at push off. Discussion: Faster walking speeds may help people post-stroke to improve their propulsion force and ankle kinematics during gait. Future studies should investigate individuals with different types of strokes as well as the percentage of speed increase that evokes consistent improvements in gait mechanics in people post-stroke for physical therapy interventions

Slow Walking in Individuals with Chronic Post-Stroke Hemiparesis: Speed Mediated Effects of Gait Kinetics and Ankle Kinematics

Post-stroke rehabilitation often aims to increase walking speeds, as faster walking is associated with improved functional status and quality of life. However, for successful community ambulation, ability to modulate (increase and decrease) walking speeds is more important than walking continuously at constant speeds. Increasing paretic propulsive forces to increase walking speed has been extensively examined; however, little is known about the mechanics of slow walking post-stroke. The primary purpose of this study was to identify the effects of increased and decreased walking speeds on post-stroke kinetics and ankle kinematics. Fifteen individuals with chronic post-stroke hemiparesis and 15 non-neurologically impaired controls walked over an instrumented treadmill under: slow, self-selected, and fast walking speeds. We examined the peak propulsive forces, propulsive impulse, peak braking forces, braking impulse, and ankle kinematics under each condition. When walking at slow walking speeds, paretic limbs were unable to reduce braking impulse and peak propulsive force or modulate ankle kinematics. Impaired modulation of paretic gait kinetics during slow walking places people post-stroke at high risks for slip-related falls. These findings suggest the need for developing gait retraining paradigms for slow walking in individuals chronically post-stroke that target the ability of the paretic limb to modulate braking forces

Slow Walking in Individuals with Chronic Post-Stroke Hemiparesis: Speed Mediated Effects of Gait Kinetics and Ankle Kinematics

Post-stroke rehabilitation often aims to increase walking speeds, as faster walking is associated with improved functional status and quality of life. However, for successful community ambulation, ability to modulate (increase and decrease) walking speeds is more important than walking continuously at constant speeds. Increasing paretic propulsive forces to increase walking speed has been extensively examined; however, little is known about the mechanics of slow walking post-stroke. The primary purpose of this study was to identify the effects of increased and decreased walking speeds on post-stroke kinetics and ankle kinematics. Fifteen individuals with chronic post-stroke hemiparesis and 15 non-neurologically impaired controls walked over an instrumented treadmill under: slow, self-selected, and fast walking speeds. We examined the peak propulsive forces, propulsive impulse, peak braking forces, braking impulse, and ankle kinematics under each condition. When walking at slow walking speeds, paretic limbs were unable to reduce braking impulse and peak propulsive force or modulate ankle kinematics. Impaired modulation of paretic gait kinetics during slow walking places people post-stroke at high risks for slip-related falls. These findings suggest the need for developing gait retraining paradigms for slow walking in individuals chronically post-stroke that target the ability of the paretic limb to modulate braking forces