The purpose of this study was to test the hypothesis that runners having different running economies show differences in the mechanical and morphological properties of their muscle-tendon units (MTU) in the lower extremities. Twenty eight long-distance runners (body mass: 76.8+/-6.7 kg, height: 182+/-6 cm, age: 28.1+/-4.5 years) participated in the study. The subjects ran on a treadmill at three velocities (3.0, 3.5 and 4.0 m s(-1)) for 15 min each. The V(O(2)) consumption was measured by spirometry. At all three examined velocities the kinematics of the left leg were captured whilst running on the treadmill using a high-speed digital video camera operating at 250 Hz. Furthermore the runners performed isometric maximal voluntary plantarflexion and knee extension contractions at eleven different MTU lengths with their left leg on a dynamometer. The distal aponeuroses of the gastrocnemius medialis (GM) and vastus lateralis (VL) were visualised by ultrasound during plantarflexion and knee extension, respectively. The morphological properties of the GM and VL (fascicle length, angle of pennation, and thickness) were determined at three different lengths for each MTU. A cluster analysis was used to classify the subjects into three groups according to their V(O(2)) consumption at all three velocities (high running economy, N=10; moderate running economy, N=12; low running economy, N=6). Neither the kinematic parameters nor the morphological properties of the GM and VL showed significant differences between groups. The most economical runners showed a higher contractile strength and a higher normalised tendon stiffness (relationship between tendon force and tendon strain) in the triceps surae MTU and a higher compliance of the quadriceps tendon and aponeurosis at low level tendon forces. It is suggested that at low level forces the more compliant quadriceps tendon and aponeurosis will increase the force potential of the muscle while running and therefore the volume of active muscle at a given force generation will decrease.

译文

这项研究的目的是检验以下假设: 具有不同跑步经济性的跑步者在下肢的肌肉肌腱单位 (MTU) 的机械和形态特性上存在差异。28名长跑运动员 (体重: 76.8 +/-6.7千克,身高: 182 +/-6厘米,年龄: 28.1 +/-4.5岁) 参加了这项研究。受试者在跑步机上以三种速度 (3.0、3.5和4.0 m s(-1)) 分别运行15分钟。通过肺活量测定法测量V(O(2)) 的消耗量。在所有三个检查的速度下,使用以250Hz运行的高速数字摄像机在跑步机上跑步时捕获左腿的运动学。此外,跑步者在测力计上的左腿以11种不同的MTU长度进行了等距最大的自愿plant屈和膝盖伸展收缩。在plant屈和膝关节伸展过程中,分别通过超声观察腓肠肌内侧 (GM) 和股外侧 (VL) 的远端腱膜。对于每个MTU,以三种不同的长度确定GM和VL的形态特性 (分束长度,顶角和厚度)。使用聚类分析根据受试者在所有三个速度下的V(O(2)) 消耗将受试者分为三组 (高运行经济,N = 10; 中等运行经济,N = 12; 低运行经济,N = 6)。GM和VL的运动学参数和形态特性均未在组之间显示出显着差异。最经济的跑步者在肱三头肌MTU中显示出更高的收缩强度和更高的归一化肌腱刚度 (肌腱力和肌腱应变之间的关系),而在低水平的肌腱力下,股四头肌腱和腱膜的顺应性更高。建议在低水平的力下,更顺应性的股四头肌腱和腱膜会增加跑步时肌肉的力势,因此在给定的力产生下活动肌肉的体积会减少。

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