De Monte Gianpiero, Arampatzis Adamantios
Institute of Biomechanics and Orthopaedics, German Sport University of Cologne, Carl-Diem-Weg 6, 50933 Cologne, Germany.
J Electromyogr Kinesiol. 2009 Apr;19(2):322-30. doi: 10.1016/j.jelekin.2007.08.005. Epub 2007 Sep 25.
The purpose of this study was to examine the moment generation of the human plantar flexors and the architecture of the gastrocnemius medialis muscle during and after shortening-stretch cycles in vivo. Fourteen male subjects (30+/-7 years, 177+/-7 cm, 80+/-9 kg) performed a series of electro-stimulated shortening-stretch plantar flexion contractions. The shortening-stretch cycles were performed at three constant angular velocities (25 degrees /s, 50 degrees /s, 100 degrees /s), two amplitudes (15 degrees and 25 degrees ankle angle changes) and at two different stimulation frequencies (30 Hz and 85 Hz). The resultant ankle joint moments were calculated through inverse dynamics. Pennation angle and fascicle length of the m. gastrocnemius medialis at rest and during contractions were measured using ultrasonography. The corresponding ankle moments, kinematics and changes in muscle architecture were analysed at seven time intervals. A three-way analysis of variance (amplitudexvelocityxstimulation frequency) and post-hoc test with Bonferroni correction were used to check the amplitude, velocity and stimulation level related effects on moment enhancement (alpha=0.05). The results show an ankle joint moment enhancement after shortening-stretch cycles influenced by muscle architectural changes. We found 2-3% isometric ankle joint moment enhancement at steady state, 1.5-2.0 s after the shortening-stretch cycle. However, the observed alteration in muscle architecture after the imposed perturbation, could lead to an underestimation (1-3%) of joint moment enhancement due to the force-length relationship of the triceps surae. Furthermore, the enhancement observed was independent of the shortening-stretch amplitude, velocity and stimulation frequency.
本研究的目的是在体内缩短-拉伸周期期间及之后，检查人类跖屈肌的力矩产生以及腓肠肌内侧头的结构。14名男性受试者（30±7岁，身高177±7厘米，体重80±9千克）进行了一系列电刺激的缩短-拉伸跖屈收缩。缩短-拉伸周期以三种恒定角速度（25°/秒、50°/秒、100°/秒）、两种幅度（踝关节角度变化15°和25°）以及两种不同刺激频率（30赫兹和85赫兹）进行。通过逆动力学计算得出踝关节合力矩。使用超声测量腓肠肌内侧头在静息状态和收缩期间的羽状角和肌束长度。在七个时间间隔分析相应的踝关节力矩、运动学和肌肉结构变化。采用三因素方差分析（幅度×速度×刺激频率）以及经Bonferroni校正的事后检验，以检查幅度、速度和刺激水平对力矩增强的相关影响（α=0.05）。结果表明，缩短-拉伸周期后踝关节力矩增强受肌肉结构变化影响。我们发现在缩短-拉伸周期后1.5 - 2.0秒的稳态下，等长踝关节力矩增强2 - 3%。然而，施加扰动后观察到的肌肉结构改变，可能由于小腿三头肌的力-长度关系导致关节力矩增强被低估（1 - 3%）。此外，观察到的增强与缩短-拉伸幅度、速度和刺激频率无关。
