Comparison of Limits of Stability Testing on Static and Dynamic Surfaces

Document Type

Article

Publication Date

5-2015

Publication Title

Medicine & Science in Sports & Exercise Supplemental

DOI

10.1249/01.mss.0000478223.98304.c7

ISSN

1530-0315

Abstract

Limits of stability (LOS) testing typically involves moving the total body center of mass (TBCM) over the base of support (BOS) to targets positioned within the theoretical LOS. Research has examined LOS testing on static and dynamic (unstable) surfaces, however different testing devices were used, thus confounding data interpretation. Additionally, whether performance on static and dynamic surfaces is related remains inconclusive.

PURPOSE: To compare TBCM to BOS distances and relationships between double leg LOS testing on static and dynamic surfaces.

METHODS: Healthy men (n=4) and women (n=5) aged 20 to 27 yrs completed static and dynamic (unstable level 8) surface LOS testing, on the Biodex SD (Biodex, Inc., Shirley, NY). A screen displayed eight targets, positioned at 75% of the subject’s theoretical LOS around a central target, and the instantaneous location of center of pressure (static) or platform orientation (dynamic). Randomly, a target became highlighted and the subject was cued to reach the target by leaning their body. Three trials of each surface/target were completed. TBCM was computed using kinematic data of 13 body segments. Closest horizontal distance between the TBCM projection on the support surface and BOS was computed upon reaching each target.

RESULTS: A significant (P=.034) surface by target interaction was revealed. Although distances were smaller for all static surface targets, post hoc testing demonstrated only one (anterior target) significant difference (95% CIdiff: .013-.046m, P=.024) between surfaces. Strong relationships were revealed for anterior (rs=.75) and anterior-left (rs=.72) targets, moderate relationships for anterior-right (rs=.52), right (rs=.50) and left (rs=.47) targets, and weak relationships for posterior-right (rs=.23), posterior (rs=.30) and posterior-left (rs=.28) targets.

CONCLUSION: Compared to static surface, during the dynamic testing subjects did not move their TBCM as close to the BOS perimeter. Thus, greater target distances should be considered for dynamic testing. Furthermore, static-dynamic relationships were not the same for all directions, suggesting that the two surfaces challenge different elements of the postural control system. Future research should consider differences in kinematics strategies between the two surfaces.

Comments

© 2015 American College of Sports Medicine

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