橢圓機運動之下肢生物力學分析

Abstract

橢圓機設計概念係模擬人走路時之運動方式，且可進行全身性運動，同時可避免地面對下肢的衝擊力。目前並無針對橢圓機對於肌肉骨骼系統進行生物力學分析之相關文獻，但若能建立完整的下肢運動學與力動學分析將可瞭解其相較於步行之優缺點，並有助於建立安全使用原則。本研究蒐集15位男性受試者，利用一配有七台紅外線攝影機之動作分析系統量測受測者從事橢圓機運動與步行時之下肢運動學資料，並利用兩塊測力板以及架設在橢圓機右踏板下方之六軸力規分別量測地面反作用力與踏板反作用力。最後再透過橢圓機運動之下肢數學模型的建立，分析運動學與力動學資料。結果顯示，橢圓機運動與步行相比，不管是運動軌跡、關節角度或關節力矩，兩者的表現皆不相同。由於橢圓機運動為閉鎖式動力鍊，加上踏板限制運動軌跡，為了有效控制質量中心之移動量，將下肢關節維持在彎曲的姿勢是必要的，這樣的改變會直接影響到關節力矩的表現。橢圓機運動是藉由擺盪腳來做推進的動作，而步長增加會增加踝關節蹠曲角度，轉速增加會使髖關節與膝關節維持在更彎曲的姿勢，至於阻力的增加則對角度並沒有影響，但此三者的改變皆會影響關節力矩的表現。雖然橢圓機運動的設計目的是為了模擬步行，但兩者運動學與力動學的表現大不相同，而不同運動參數對關節有不同的影響，因此使用上必須考量使用者關節及軟組織的功能，以避免不必要的運動傷害。

Design concepts of elliptical trainers were reported to simulate the motion of the human gait, providing whole body motion and reducing impact loading to the lower limbs. Despite the growing popularity in recent years of the elliptical exercise (EE), the biomechanics of the lower extremities during EE remains unknown. However, a complete knowledge on the biomechanics of the lower limbs would be helpful for realizing the advantage and disadvantage of EE when compared to the overground walking and establishing the guideline for safe usage. Fifteen male adults were recruited to perform EE and overground walking. Lower limb kinematics was obtained using a 7-camera motion analysis system. Two forceplates and a 6-component force transducer instrumented under right pedal were used for ground/pedal reaction forces measurement. The results showed that EE and overground walking were of fundamental differences both kinematically and kinetically. All of the stride length, workload and pedal rate influenced the lower limb kinetics during EE, while stride length affected ankle plantarflexion and pedal rate affected hip and knee flexion angles. The results suggested that the use of the ET for healthy users and rehabilitative training would have to consider users’ joint function and muscle strength to avoid any unnecessary injuries.