Adaptive postural control for joint immobilization during multitask performance
Journal
PLoS ONE
Journal Volume
9
Journal Issue
10
Pages
e108667
Date Issued
2014
Author(s)
Abstract
Motor abundance is an essential feature of adaptive control. The range of joint combinations enabled by motor abundance provides the body with the necessary freedom to adopt different positions, configurations, and movements that allow for exploratory postural behavior. This study investigated the adaptation of postural control to joint immobilization during multi-task performance. Twelve healthy volunteers (6 males and 6 females; 21-29 yr) without any known neurological deficits, musculoskeletal conditions, or balance disorders participated in this study. The participants executed a targeting task, alone or combined with a ball-balancing task, while standing with free or restricted joint motions. The effects of joint configuration variability on center of mass (COM) stability were examined using uncontrolled manifold (UCM) analysis. The UCM method separates joint variability into two components: the first is consistent with the use of motor abundance, which does not affect COM position (VUCM); the second leads to COM position variability (VORT). The analysis showed that joints were coordinated such that their variability had a minimal effect on COM position. However, the component of joint variability that reflects the use of motor abundance to stabilize COM (VUCM) was significant decreased when the participants performed the combined task with immobilized joints. The component of joint variability that leads to COM variability (VORT) tended to increase with a reduction in joint degrees of freedom. The results suggested that joint immobilization increases the difficulty of stabilizing COM when multiple tasks are performed simultaneously. These findings are important for developing rehabilitation approaches for patients with limited joint movements. ? 2014 Wei-Li Hsu.
Other Subjects
adaptive behavior; adult; age distribution; Article; body equilibrium; body position; female; human; human experiment; joint function; joint mobility; joint stability; male; normal human; range of motion; sex difference; standing; task performance; volunteer; adaptation; biomechanics; joint; joint characteristics and functions; movement (physiology); physiology; Adaptation, Physiological; Adult; Biomechanical Phenomena; Female; Humans; Joints; Male; Movement; Postural Balance; Range of Motion, Articular
Publisher
Public Library of Science
Type
journal article