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M. Anan1, T. Ibara2, K. Hada2
1Oita University, Faculty of Welfare and Health Science, Oita, Japan, 2Kawashima Clinic, Department of Rehabilitation, Nakatsu, Japan
Background: In a standing position and gait, the covariation structure of each body movement element, such as the joints that contribute to motion, stabilize the center of gravity (COG) position. In physical therapy, balance training using visual feedback with a posture mirror is performed for fall prevention training in the older people, to improve static balance. However, in this posture control task, when visual feedback changes, the posture control strategy and the joint movement coordination structure may change.
Purpose: The purpose of this study was to clarify whether the posture control strategy and joint movement coordination structure change when visual feedback changes, with one-leg standing task motions for healthy older people.
Methods: The subjects were 26 healthy older people. For the task motion, one-leg standing was used with the dominant foot as the supporting leg. The experimental conditions included a normal condition (normal), a mirror feedback condition (mirror), and a condition for visualizing the COG in real time (COG). Kinematics and kinetics data were measured using a three-dimensional motion analysis system and floor reaction forces. From the obtained data, the total length (LNG), rectangular area (REC), and root mean square (RMS) of the COG displacements and the variance of each joint angle for 10 s were calculated. UCM analysis is used to quantify the joint movement coordination structure that contributes to the stabilization of the motion. The task variable is the COG displacement, and the element variable is each joint angle. We calculated good fluctuation (VUCM), which does not affect the task achievement, and bad fluctuation (VORT), which affects task achievement. Statistical analyses were performed using two-way analysis of variance to compare the coordination structures among the three conditions and one-way analysis of variance for the others. The significance level was < 5%.
Results: The variances of the ankle, knee, and hip angles with the supporting leg, as well as that of the lumbar and cervical angles, were significantly lower in the COG condition than in the normal condition. REC and RMS were significantly lower in the COG condition than in the normal condition. LNG was significantly lower in the COG and mirror conditions than in the normal condition. VUCM did not significantly differ between conditions, but VORT was significantly lower in the mirror condition than in the normal condition.
Conclusion(s): Visual feedback with a mirror can enhance the COG control function and reduce fluctuations that fail to stabilize the COG; however, joint movement variations could not be reduced in healthy older individuals. On the other hand, visual feedback with visualizing the COG can stabilize the COG and provide a feasible posture control strategy that reduces joint movement variations.
Implications: Our findings suggest that visual feedback of the COG for older people provides a posture control strategy that stabilizes the COG and reduces joint movement variations. This strategy is superior to visual feedback practices that employ full-body mirrors.
Funding, acknowledgements: This study was supported by a Grant-in-Aid 17K01510 from the Japan Society for the Promotion of Science.
Keywords: older people, visual feedback, coordination
Topic: Older people
Did this work require ethics approval? Yes
Institution: Oita University
Committee: Oita University Medical School Ethical Review Boards
Ethics number: 1259‐T2
All authors, affiliations and abstracts have been published as submitted.
