Effect of Fatigue on Anticipatory Postural Adjustment in Static and Dynamic Balance

疲勞對動態平衡與靜態平衡預期性姿勢調整的影響

梅氏福(Phuc Thi Mai) ； 李國勝(Guo-Sheng Li) ； 張雅如(Ya-Ju Chang)

《物理治療》 42卷4期 (2017/12) Pp. 357-357

https://doi.org/10.6215/FJPT.2017.74.P26

摘要

Background and Purpose: The anticipatory postural adjustments (APAs) has important role in maintaining static and dynamic balance and propelling the body mass forward and laterally prior to the first step. Among postural muscles, the tibialis anterior (TA) muscles is considered the onset of gait initiation. Thus, the purpose of this study was to investigate the effect of fatigue of TA muscle on the variability of APAs in gait initiation (dynamic balance) and in response to external perturbation (static balance) with or without cue. Methods: A healthy young male adults performed an isometric TA muscle fatigue task. Before and after fatigue task, maximum voluntary contraction (MVC) measurements were recorded. In dynamic balance task, APA was recorded by self-initiated gait trials with or without visual line cue on the walkway. In static balance task, response to anterior external perturbation with or without auditory cue when subjects stood with eye open. The weight loading and muscle activity at MVC and during fatigue task were recorded to assess the presence of fatigue. The onset and amplitude of center of pressure (COP) displacement were calculated. Results: After fatigue, electromyographic (EMG) mean, median frequency and weight loading of tibialis anterior muscle decreased. Dynamic balance trials data shown shorter APA duration, smaller amplitude of COP displacement after fatigue and the COP amplitude smaller with cue than without cue. In static balance task, smaller amplitude were found in both conditions, meanwhile, the APA duration were shorter with cue and longer without cue. Conclusion: The findings supported for the role of APA as a consistent functional adaptation adjusted by the central nervous system to maintain postural stability in the presence of fatigue. Moreover, the larger amplitude of COP after fatigue in gait initiation without cue may suggest us as a possible effective treatment for patients with Parkinson’s disease who have deficit in gait initiation. Clinical Relevance: Our results provide important information to help the design of intervention program for improvement the difficulty in gait initiation of individuals but further studies in patients group with more subjects are suggested.