Lin I.-S.1, Hsu W.-L.1,2, Lau P.Y.1, Chien J.-E.1, Su P.-Y.1
1National Taiwan University, College of Medicine, School and Graduate Institute of Physical Therapy, Taipei, Taiwan, 2National Taiwan University Hospital, Physical Therapy Center, Taipei, Taiwan
Background: Upright balance control in older adults is an important issue for fall prevention. Sensory information such as visual, vestibular, and proprioceptive information are integrated and affect the balance control. Therefore, underling balance control strategy among older adults needs to be identified. However, which sensory information is dominant for older adults when standing on the different surfaces were still uncertain.
Purpose: The aim of study was to determine the effects of surface support on postural control mechanism in healthy older adults.
Methods: Twenty-two healthy older adults (65-81 years) and twenty-two healthy younger adults (19-26 years) were recruited for healthy older adults group and healthy younger adults group, respectively. Subjects were asked standing for 120 seconds on two different support surface conditions: the force platform and the wooden-brick. Two trials for each condition were collected. The moderate frequency (1.56-6.25 Hz) bandwidth of the center of pressure sway in the anterior-posterior (AP) direction, which is related to muscular proprioception of lower limbs, and the sway area of the center of pressure were calculated. Two-way ANOVA was used to determine the difference of the moderate frequency bandwidth and sway area between two groups.
Results: The significant main effects on surface and on group were found respectively in moderate frequency range of the COP sway in the anterior-posterior direction (F=99.66, p 0.001; F= 6.35, p=0.015). In addition, only the significant main effect on surface support was found in sway area of the COP. (F=27.16, p 0.001)
Pairwise comparison between two support surface conditions showed the percentage of the moderate frequency range in brick-standing condition was significantly greater than those in the over-ground condition for both groups (F=88.71, p 0.001; F=21.67, p 0.001). In addition, the moderate frequency range of the COP sway in the older adults is significantly higher than those in the younger adults when standing on the brick (F= 10.96, p 0.005). The sway area of COP in brick-standing condition for both two groups was significantly greater than the one in over-ground condition (Old: F=17.36, p 0.001; Young: F=10.27, p 0.005).
Conclusion(s): The result of this study indicated the percentage of moderate frequency range increased significantly when standing on the bricks compared with standing over-ground. It might indicate that the muscular proprioception of the lower limbs was dominant for adapting to the changes of the base of support, especially for the older adults group. In addition, the sway area of COP between the two conditions had significant difference for both groups, but no significant difference was found between the older and the young adults. The result provides the information that standing on the bricks is indeed a challenged task either for the older or for the young adults.
Implications: This study identified the balance control strategy of the older adults in different support surfaces which provides important information for fall prevention in the older adults.
Funding acknowledgements: Supported by the National Health Research Institutes (NHRI-EX105-10218EC), the Ministry of Science and Technology (105-2628-E-002-006-MY3), and National Taiwan University (NTU-CDP-105R780).
Topic: Human movement analysis
Ethics approval: This study has been approved by the Research Ethics Committee of the National Taiwan University Hospital.
All authors, affiliations and abstracts have been published as submitted.
