Abnormal volitional hip torque phasing and hip impairments in gait post stroke.

Area of Science:

• Neurorehabilitation
• Biomechanics
• Stroke Recovery

Background:

• Stroke frequently impairs motor control, affecting walking ability.
• Volitional control of hip torque is crucial for effective gait post-stroke.

Purpose of the Study:

• To quantify the relationship between volitional hip torque control and walking function in individuals with chronic stroke.
• To investigate abnormalities in hip torque phasing and magnitude in the paretic limb during controlled movements.

Main Methods:

• Assessed volitional hip flexion and extension torques using a robotic system in 11 chronic stroke survivors and 5 controls.
• Measured hip, knee, and ankle torques, and surface electromyography during in-phase, out-of-phase, and unilateral hip movements.
• Performed over-ground gait analysis for all stroke participants.

Main Results:

• The paretic limb produced peak hip torques during muscle stretch, unlike controls and the non-paretic limb.
• Abnormal hip torque phasing in the paretic limb was more pronounced during bilateral movements and linked to quadriceps overactivity.
• Flexion torque magnitude correlated with Fugl Meyer Score, walking speed, and hip extension during gait.

Conclusions:

• Hyperexcitable stretch reflexes in the paretic limb likely impair coordinated hip torque phasing.
• Impaired hip torque phasing significantly interferes with walking function post-stroke.
• Targeting stretch reflex abnormalities may improve gait rehabilitation in stroke survivors.