Muscular responses to upper body mediolateral angular momentum perturbations during overground walking

Area of Science:

• Biomechanics
• Neuroscience
• Human Motor Control

Background:

• Maintaining balance during bipedal locomotion requires adaptive motor control and muscle coordination.
• The specific roles of muscles and neural circuitry in balance recovery from perturbations are debated.

Purpose of the Study:

• To investigate human motor control strategies during recovery from trunk perturbations.
• To analyze muscle activation patterns in response to different perturbation timings and directions.

Main Methods:

• Utilized a portable Angular Momentum Perturbator (AMP) to apply perturbation torques to the upper body.
• Recorded electromyography (EMG) of eight lower-limb muscles in ten participants during stance and touchdown phases.
• Applied frontal plane perturbations in ipsilateral and contralateral directions.

Main Results:

• Hip strategies were primarily used to counteract perturbation torques, with occasional ankle strategy use.
• Proximal muscles, especially the Rectus Femoris, showed consistently higher activation.
• Fastest muscle reactions originated from muscles near the perturbation site, with activation timing dependent on perturbation specifics.

Conclusions:

• Findings advance reflex response modeling for predicting disturbances.
• Results can inform the development of assistive devices and clinical interventions, particularly for the elderly.