近年來運動休閒風潮的盛行，加強上肢肌肉的訓練是非常重要的，如何在訓練過程中避免受傷是更重要的課題。本文的目的主要是希望能夠探究手肘過度伸展在動力鏈運動對上肢肘關節負荷之影響。
24位無上肢傷殘病史的年輕男性受測者受邀參與此實驗計畫(12位手肘正常伸展者及12位手肘過度伸展者)。讓此兩組不同手肘彎曲情況之受測者進行屬於開放動力鏈的仰臥推舉運動及屬於閉鎖動力鏈的伏地挺身運動。實驗使用到的儀器包含8部高速數位攝影機的三維動態分析系統及用以量測作用力位置及手掌反作用力的測力板。同時也使用表面肌電訊號感測器來收集肌肉活化之情形。
在屬於閉鎖動力鏈的伏地挺身運動中，手肘過度伸展(Hyper-extension)在末期85~100%的肘關節屈曲、伸展角加速度明顯大過於手肘正常彎曲者(Normal)。手肘過度伸展者(Hyper-extension)在末期85~100%時，肘關節的內外側力變化率的部分皆大過肘正常彎曲者(Normal)。其手肘屈曲、伸展變化角度(Range of Motion)皆多過手肘彎曲正常者(Normal)，手肘過度伸展者(Hyper-extension)相對於手肘彎曲正常者(Normal)作了更多的功。
在屬於開放動力鏈的仰臥推舉運動過程中，手肘過度伸(Hyper-
extension)在末期85~100%的肘關節屈曲、伸展角加速度明顯大過於手肘正常彎曲(Normal)。手肘過度伸展者(Hyper-extension)，在末期85~100%時，肘關節的前後向力變化率、內外側力變化率皆大過肘正常彎曲者(Normal)。其手肘屈曲、伸展變化角度(Range of Motion)皆多過手肘彎曲正常者(Normal)，手肘過度伸展者(Hyper-extension)相對於手肘彎曲正常者(Normal)作了更多的功。
本研究分析了不同上肢手肘伸展情況(正常伸展及過度伸展)之差異性，也分析了肘關節角度在到達過度伸展之後的力變化率及肘關節屈曲、伸展角加速度之改變情況。建議對於手肘過度伸展情況者在運動過程中手肘在達到過度伸展角度時，必須非常注意。盡可能的控制不去做最主動的運動以避免受傷。

Exercise and Strengthening of the Upper Extremity is becoming popular. How to avoid injuries during training process is an important issue. The purpose of this study was to investigate the effect of hyper-extension on elbow joint loading during kinetic chain exercise of the upper extremity.
Twenty-four healthy male students with no trauma history volunteered for this study(twelve for elbow normal type and elbow hyper-extension type each). They were asked to complete open kinetic chain(Bench press) and closed kinetic chain(Pushup). The Expert Vision Motion Analysis System with eight CCD cameras, and a Kistler force plate was used to measure the relative joint position and ground reaction force. Also surface EMG was used to measure muscle activity.
During closed kinetic chain exercise(Pushup), elbow hyper-extension type was found has greater elbow flexion/extension angular acceleration and greater elbow internal/external force change rate during cycle of 85% ~ 100% period. Also larger range of motion for elbow hyper-extension type which makes greater work during one cycle.
During open kinetic chain exercise(Bench press), elbow hyper-extension type was found has greater elbow flexion/extension angular acceleration and greater elbow internal/external and anterior/posterior force change rate during cycle of 85% ~ 100% period. Also larger range of motion for elbow hyper-extension type which makes greater work during one cycle.
This study provides information about the difference between elbow normal type and elbow hyper-extension type of the upper extremities, and how force change rate and Elbow flexion/extension angular acceleration changed occurred at the elbow beyond Hyper-extension. We suggested that elbow Hyper-extension subjects must be careful during cycle of 85%~100%. As possible as elbow Hyper-extension subjects can not to do the active exercise to avoid elbow injuries.

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