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Is postural control during unstable sitting a proxy measure for determinants associated with lumbar stability?
Christian Larivière1, Richard Preuss2, Daniel Ludvig3
1Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST), Montreal, Quebec, Canada; Center for Interdisciplinary Research in Rehabilitation of Greater Montreal (CRIR), Montreal, Quebec, Canada.
Journal of Biomechanics
|January 7, 2020
Summary
Unstable sitting effectively measures lumbar stability determinants, including muscle thickness and movement control. This provides a practical proxy for assessing trunk postural control (TPC) in clinical and research settings.
Area of Science:
- Biomechanics
- Motor Control
- Rehabilitation Science
Background:
- Lumbar stability is crucial for trunk postural control (TPC).
- Traditional assessments of lumbar stability determinants can be time-consuming and equipment-intensive.
- Unstable sitting (e.g., on a wobbling chair) offers a potential alternative for evaluating TPC.
Purpose of the Study:
- To investigate if determinants of lumbar stability can predict performance in unstable sitting tasks.
- To establish unstable sitting as a potential proxy measure for lumbar stability determinants.
Main Methods:
- Fifty-eight subjects underwent unstable sitting tests using an inertial sensor to measure TPC outcomes.
- Subjects also completed trunk neuromuscular tests assessing muscle thickness, lumbar proprioception, stiffness, feedforward/feedback control, and coordination.
- Multivariate analyses were employed to identify predictors of TPC performance.
Main Results:
- Four to five key predictors explained 36-47% of the variance in TPC outcomes.
- Predictors included kinematic parameters, lumbar stiffness, connective tissue thickness, and muscle activation timing (IO/TrA, iliocostalis lumborum).
- Lumbar proprioception and reflex responses were not significant predictors in this study.
Conclusions:
- Trunk postural control during unstable sitting serves as a valid proxy for key lumbar stability determinants.
- This finding supports the use of unstable sitting as a time- and resource-efficient assessment tool.
- The results have implications for both research and clinical practice in evaluating spinal stability.
