Tsaopoulos Dimitrios E, Baltzopoulos Vasilios, Richards Paula J, Maganaris Constantinos N
Institute for Biophysical & Clinical Research into Human Movement, Manchester Metropolitan University, Alsager ST7 2HL, UK.
J Biomech. 2007;40(15):3325-32. doi: 10.1016/j.jbiomech.2007.05.005. Epub 2007 Jul 2.
The purpose of this study was to examine the effect of different muscle contraction modes and intensities on patellar tendon moment arm length (d(PT)). Five men performed isokinetic concentric, eccentric and passive knee extensions at an angular velocity of 60 deg/s and six men performed gradually increasing to maximum effort isometric muscle contractions at 90( composite function) and 20( composite function) of knee flexion. During the tests, lateral X-ray fluoroscopy imaging was used to scan the knee joint. The d(PT) differences between the passive state and the isokinetic concentric and extension were quantified at 15( composite function) intervals of knee joint flexion angle. Furthermore, the changes of the d(PT) as a function of the isometric muscle contraction intensities were determined during the isometric knee extension at 90( composite function) and 20( composite function) of knee joint flexion. Muscle contraction-induced changes in knee joint flexion angle during the isometric muscle contraction were also taken into account for the d(PT) measurements. During the two isometric knee extensions, d(PT) increased from rest to maximum voluntary muscle contraction (MVC) by 14-15%. However, when changes in knee joint flexion angle induced by the muscle contraction were taken into account, d(PT) during MVC increased by 6-26% compared with rest. Moreover, d(PT) increased during concentric and eccentric knee extension by 3-15%, depending on knee flexion angle, compared with passive knee extension. These findings have important implications for estimating musculoskeletal loads using modelling under static and dynamic conditions.
本研究的目的是探讨不同肌肉收缩模式和强度对髌腱力臂长度（d(PT)）的影响。五名男性以60度/秒的角速度进行等速向心、离心和被动膝关节伸展，六名男性在膝关节屈曲90°（复合函数）和20°（复合函数）时进行逐渐增加至最大努力的等长肌肉收缩。在测试过程中，使用外侧X射线荧光透视成像扫描膝关节。在膝关节屈曲角度的15°（复合函数）间隔处量化被动状态与等速向心和伸展之间的d(PT)差异。此外，在膝关节屈曲90°（复合函数）和20°（复合函数）的等长膝关节伸展过程中，确定d(PT)随等长肌肉收缩强度的变化。在进行d(PT)测量时，也考虑了等长肌肉收缩期间肌肉收缩引起的膝关节屈曲角度变化。在两次等长膝关节伸展过程中，d(PT)从静息状态增加到最大自主肌肉收缩（MVC）时增加了14% - 15%。然而，当考虑到肌肉收缩引起的膝关节屈曲角度变化时，MVC期间的d(PT)与静息状态相比增加了6% - 26%。此外，与被动膝关节伸展相比，向心和离心膝关节伸展期间的d(PT)根据膝关节屈曲角度增加了3% - 15%。这些发现对于在静态和动态条件下使用模型估计肌肉骨骼负荷具有重要意义。
