Citation

Allen JL, Franz J. J. Neurophysiol. 2018; 120(5): 2368-2378.

Affiliation

Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, United States.

Copyright

(Copyright © 2018, American Physiological Society)

DOI

10.1152/jn.00302.2018

PMID

30133380

Abstract

Older adults are at a high risk of falls, and most falls occur during locomotor activities like walking. This study aimed to improve our understanding of changes in neuromuscular control associated with increased falls risk in older adults in the presence of dynamic balance challenges during walking. Motor module (a.k.a. muscle synergy) analyses identified changes in the neuromuscular recruitment of leg muscles during walking with and without perturbations designed to elicit the visual perception of lateral instability. During normal walking we found that falls history (but not age) was associated with reduced motor module complexity, and that age (but not falls history) was associated with increased step-to-step variability of module recruitment timing. Further, motor module complexity was unaltered in the presence of optical flow perturbations. The specific effects of falls history on leg muscle recruitment included an absence and/or inability to independently recruit motor modules normally recruited to perform biomechanical functions important for walking balance control. These results suggest that fallers do not recruit the appropriate motor modules necessary for well-coordinated walking balance control even in the presence of perturbations. The identified changes in the modular control of walking balance in older fallers may either represent a neural deficit that leads to poor balance control, or a prior history of falls results in a compensatory motor adaptation. In either case, our study provides initial evidence that a reduced motor repertoire in older adult fallers may be a constraint on their ability to appropriately respond to balance challenges during walking.

Language: en

Keywords

gait; muscle synergy; stability; virtual reality; vision