步態機械能量流分析與臨床應用

Abstract

背景： 機械能量流為整合運動學與力動學資料之數學量，可將片段之肢段運動與關節角度、力矩、功率等資訊整合成完整且系統性的構圖，清晰地顯現致使動作產生的能量來龍去脈。如何表達與應用其深厚與豐富的內涵成為本研究的重點目標。 本研究的目的是建立能量流模型，並應用此模型深入探討正常人步態之能量流動特徵與動作策略。 方法： 本研究使用三維動作分析系統收集正常年輕人與正常老年人的步態資料，經由整合下肢各肢段與關節之能量流數據，建構出正常年輕人於push-off時期之能量流動路徑圖，並使用因素分析，萃取並比較正常年輕人與正常老年人於不同步行速度下之擺盪期(swing phase)能量流動特徵。 結果： 收集八名正常年輕人資料的研究結果顯示在push-off時期，踝關節產生之能量絕大多數是用以提昇同側肢段之動能，而傳遞至骨盆的能量僅是踝關節產生最大能量值之10%。收集十名正常年輕人與十名正常老年人資料的因素分析結果顯示，正常年輕人於自選步行速度與快速步行之情況下，皆呈現相似地擺盪期能量流動特徵。而正常老年人於快速步行之情況下，其擺盪期能量流動特徵與自選步行速度下之呈現特徵相反。 結論： 本研究已開發一個能量流模型，建立關節能與肢段能之橋段，其中關鍵之能量流參數可對應到現今習用之動作分析參數如關節功率與肢段動位能變化率等。透過觀察與分析模型中機械能之流動特徵，可直覺式地推論動作策略的能量調節機制，提供臨床研究人員從整體探討動作策略與能量使用效率之有利工具。本研究亦嘗試提供另一種能量流模型之應用方法，從高維度之能量流資料中，使用因素分析來比較不同族群間能量流動模式之差異。

Background: Mechanical energy flow of human movement is an integrated presentation of kinematics and kinetics, which provides a systematic picture and potentially could be a powerful tool for clinicians and researchers to look into the movement strategies and energy efficiency of human movement. The purpose of this research is to develop an energy flow model with a perspective on bridging joint and segmental energetics. The energy flow model is utilized to investigate walking strategy adopted by the healthy young adults and the elders in order to demonstrate clinical applications of the developed energy flow model. Method: Healthy young adults and healthy elders were be recruited in this research. Gait data of all participants were captured by three-dimensional motion capture system. Energetic data of the pelvis and lower limb were used to construct an energy flow diagram at the instant of peak ankle power generation during push-off in young adults. The factor analysis was then applied to extract the high-dimensional energy flow characteristics of the swing leg in young adults and the elders. Results: Results of 8 healthy young adults suggest that the ankle mainly contributes to increase the kinetic energy of the ipsilateral leg in preparation for swing during push-off. The magnitude of the power flowing to the pelvis, which could be used for forward propulsion, was only 10% of that generated by the ankle. The results of factor analysis of 10 healthy young adults and 10 healthy elders showed that the young adults have similar energy flow characteristics of the swing leg for both fast and self-selected walking speeds, while the elderly showed an opposite energy flow pattern especially at the fast walking speed. The hip power and the knee power were also found to mainly correspond to the swing acceleration and deceleration, respectively. Conclusions: A new symbolic convention of energy flow diagram was developed to manifest where the generated ankle power is transmitted to in order to ease of interpreting the function of the ankle. By comparing the energy flow characteristics of the elders with young adults, this research demonstrated a valuable tool to explore the change of the gait characteristics in the elderly and could help to facilitate the understanding of the neuromuscular adaptation due to aging. The proposed energy flow analysis is also a useful analytic tool with applications across many disciplines, for example, evaluating the energy performance of elite athletes, designing the powered prostheses, and revealing the compensatory movement strategy of people with disabilities.