Foot force direction control during leg pushes against fixed and moving pedals in persons post-stroke

Area of Science:

• Biomechanics
• Neurorehabilitation
• Human Movement Science

Background:

• Muscle action generates foot force (F(m)) with consistent direction during healthy pedaling.
• Stroke-induced hemiparesis can alter motor control and muscle activation patterns.

Purpose of the Study:

• To investigate how stroke affects the control of muscle-generated foot force (F(m)) during pedaling.
• To compare F(m) orientation between paretic and non-paretic limbs after stroke.

Main Methods:

• Ten individuals with hemiparesis performed pushing efforts on a stationary cycle ergometer.
• Measurements were taken under both fixed- and moving-pedal conditions.
• Foot force (F(m)) direction and orientation were analyzed in sagittal and frontal planes.

Main Results:

• F(m) direction remained constant with increasing force magnitude in both limbs and conditions.
• The paretic limb exhibited altered F(m) orientation compared to the non-paretic limb.
• Paretic limb orientation shifts were consistent with muscle weakness and altered activation post-stroke.

Conclusions:

• Lower limb force control post-stroke may involve distinct magnitude and direction organization.
• Altered F(m) orientation in the paretic limb suggests stroke-specific adaptations in muscle recruitment.
• Limb posture might influence muscle activation levels during pedaling efforts.