Modular organization across changing task demands in healthy and poststroke gait

Area of Science:

• Neuroscience
• Biomechanics
• Rehabilitation Science

Background:

• Post-stroke motor impairments significantly affect mobility.
• Understanding muscle coordination patterns is crucial for rehabilitation.

Purpose of the Study:

• To investigate the relationship between impaired muscle module patterns and mobility task performance in post-stroke individuals.
• To compare muscle coordination strategies between post-stroke and healthy individuals during various walking tasks.

Main Methods:

• Collected kinematic, kinetic, and electromyography (EMG) data during treadmill walking in post-stroke and healthy subjects.
• Utilized nonnegative matrix factorization to identify muscle synergy modules from EMG data.
• Analyzed module composition and timing across self-selected walking and four maximal effort mobility tasks.

Main Results:

• Identical underlying muscle modules were employed by both healthy and post-stroke subjects for steady-state walking and mobility tasks.
• Healthy subjects demonstrated adaptability in muscle module timing, but not composition, with altered task demands.
• Post-stroke subjects showed limited adaptability in muscle module timing, correlating with reduced mobility capabilities.

Conclusions:

• Muscle synergy organization is preserved post-stroke, but the ability to modulate module timing for task-specific demands is impaired.
• This timing adaptability deficit may underlie functional mobility limitations in individuals with stroke.
• Targeting motor timing adaptability could be a key strategy in stroke rehabilitation.