Effects of restraining forces on propulsion and other gait characteristics during treadmill walking post-stroke

BACKGROUND: A decreased propulsive capacity post stroke is associated with a diminished walking ability. When walking with a restraining force applied to the pelvis, more propulsion is required to enable forward progression. This may stimulate propulsion capacity in people post-stroke. Before incorporating restraining forces into training, their effects on propulsion mechanics and other gait characteristics must be evaluated. This study investigated: (1) the immediate bilateral effects of restraining forces during treadmill walking on propulsive force, braking force, and mechanical work in people post-stroke, and (2) the impact of this manipulation on step length symmetry, single support time symmetry and muscle activity. Additionally, we explored whether these effects vary with gait speed and force magnitude. METHODS: 13 individuals post-stroke walked on a treadmill at 0.28 m/s and 0.56 m/s while a horizontal restraining force (0 %, 5 % or 10 % of their body weight) was applied to the pelvis. During walking, ground reaction forces and muscle activity of gluteus Medius, rectus Femoris, vastus Medialis, biceps Femoris, tibialis anterior, medial gastrocnemius and soleus were bilaterally recorded FINDINGS: Applying restraining forces up to 10 % of body weight increased propulsive impulse and mechanical work while reducing braking impulse. Although no significant effects were found on step length symmetry or swing phase symmetry, subtle changes in muscle activity were observed when walking with restraining forces INTERPRETATION: Restraining forces up to 10 % of body weight can activate propulsive capacity. Future research should explore how this direct effect translates into long-term training effects.