Carroll Andrew M, Lee David V, Biewener Andrew A
Biology Department, University of Evansville, Evansville, IN, USA.
J Appl Physiol (1985). 2008 Oct;105(4):1262-73. doi: 10.1152/japplphysiol.01316.2007. Epub 2008 Jul 24.
We investigate how the biarticular long head and monoarticular lateral head of the triceps brachii function in goats (Capra hircus) during jumping and landing. Elbow moment and work were measured from high-speed video and ground reaction force (GRF) recordings. Muscle activation and strain were measured via electromyography and sonomicrometry, and muscle stress was estimated from elbow moment and by partitioning stress based on its relative strain rate. Elbow joint and muscle function were compared among three types of limb usage: jump take-off (lead limb), the step prior to jump take-off (lag limb), and landing. We predicted that the strain and work patterns in the monoarticular lateral head would follow the kinematics and work of the elbow more closely than would those of the biarticular long head. In general this prediction was supported. For instance, the lateral head stretched (5 +/- 2%; mean +/- SE) in the lead and lag limbs to absorb work during elbow flexion and joint work absorption, while the long head shortened (-7 +/- 1%) to produce work. During elbow extension, both muscles shortened by similar amounts (-10 +/- 2% long; -13 +/- 4% lateral) in the lead limb to produce work. Both triceps heads functioned similarly in landing, stretching (13 +/- 3% in the long head and 19 +/- 5% in the lateral) to absorb energy. In general, the long head functioned to produce power at the shoulder and elbow, while the lateral head functioned to resist elbow flexion and absorb work, demonstrating that functional diversification can arise between mono- and biarticular muscle agonists operating at the same joint.
我们研究了山羊（Capra hircus）在跳跃和着陆过程中肱三头肌的双关节长头和单关节外侧头是如何发挥作用的。通过高速视频和地面反作用力（GRF）记录来测量肘部力矩和功。通过肌电图和超声测量法来测量肌肉激活和应变，并根据肘部力矩以及基于其相对应变率划分应力来估算肌肉应力。在三种肢体使用类型之间比较肘关节和肌肉功能：跳跃起跳（领先肢体）、跳跃起跳前的一步（滞后肢体）和着陆。我们预测，单关节外侧头的应变和功模式将比双关节长头更紧密地跟随肘部的运动学和功。总体而言，这一预测得到了支持。例如，外侧头在领先和滞后肢体中伸展（5±2%；平均值±标准误）以在肘部屈曲和关节功吸收过程中吸收功，而长头缩短（-7±1%）以产生功。在肘部伸展过程中，领先肢体中的两块肌肉缩短量相似（长头为-10±2%；外侧头为-13±4%）以产生功。两块肱三头肌在着陆时功能相似，伸展（长头为13±3%，外侧头为19±5%）以吸收能量。总体而言，长头的功能是在肩部和肘部产生力量，而外侧头的功能是抵抗肘部屈曲并吸收功，这表明在同一关节处起作用的单关节和双关节肌肉激动剂之间可能会出现功能多样化。
