Repeated Exposure to Forward Support-Surface Perturbation During Overground Walking Alters Upper-Body Kinematics and Step Parameters

ABSTRACT

Locomotion requires both proactive and reactive control strategies to maintain balance. The current study aimed to: (i) ascertain upper body postural responses following first exposure to a forward (slip) support-surface perturbation; (ii) investigate effects of repeated perturbation exposure; (iii) establish relationships between arms and other response components (trunk; center of mass control). Young adults (N = 11) completed 14 walking trials on a robotic platform; six elicited a slip response. Kinematic analyses were focused on extrapolated center of mass position (xCoM), bilateral upper- and forearm elevation velocity, trunk angular velocity, and step parameters. Results demonstrated that postural responses evoked in the first slip exposure were the largest in magnitude (e.g., reduced backward stability, altered reactive stepping, etc.) and preceded by anticipatory anterior adjustments of xCoM. In relation to the perturbed leg, the large contra- and ipsilateral arm responses observed (in first exposure) were characteristically asymmetric and scaled to the degree of peak trunk extension. With repeated exposure, xCoM anticipatory adjustments were altered and in turn, reduced posterior xCoM motion occurred following a slip (changes plateaued at second exposure). The few components of the slip response that persisted across multiple exposures did so at a lesser magnitude (e.g., step length and arms).

Keywords:

• dynamic stability
• gait changes
• slip support-surface perturbations
• upper body response

ACKNOWLEDGMENTS

The authors would like to acknowledge funding provided by a Canadian Foundation for Innovation and Ontario Research Fund Research Infrastructure grants for equipment; a College of Biological Science Faculty Assistance Scholarship awarded to AHH and Natural Science and Engineering Council of Canada via a Discovery Grant awarded to LAV. The authors would also like to extend their appreciation to Dr. John Zettel for use of laboratory equipment.

TRANSMITTAL LETTER

The current submission is an Original Article. Each of the authors has read and concurs with the content in the final manuscript. The material within has not been and will not be submitted for publication elsewhere except as an abstract. All authors have met the contribution requirements as laid out by the journal of Journal of Motor Behavior.

Additional information

Funding

Natural Sciences and Engineering Research Council of Canada (Grant #261854).