Kawakami Y, Abe T, Fukunaga T
Department of Sports Sciences, College of Arts and Sciences, University of Tokyo, Japan.
J Appl Physiol (1985). 1993 Jun;74(6):2740-4. doi: 10.1152/jappl.1993.74.6.2740.
Muscle-fiber pennation angles were measured in vivo with the use of ultrasonography to investigate the relationship between fiber pennation and muscle size for 32 male subjects (from untrained subjects to highly trained bodybuilders). From the image of a B-mode ultrasonogram, fiber pennation angles and thickness of triceps brachii were determined, the former as angles between echoes from the interspaces of fascicles and from the aponeurosis of long and medial heads of triceps and the latter as the distance between the fat-muscle and muscle-bone interfaces. The pennation angles were in the range of 15 and 53 degrees for the long head and 9 to 26 degrees for the medial head, which were similar to or greater than the published and the present data on human cadavers. Significant differences were observed between normal subjects and bodybuilders in muscle thickness and pennation angles (P < 0.01), and there were significant correlations between muscle thickness and pennation angles for both long (r = 0.884) and medial (r = 0.833) heads of triceps, suggesting that muscle hypertrophy involves an increase in fiber pennation angles.
通过超声检查在体内测量了32名男性受试者（从未受过训练的受试者到训练有素的健美运动员）的肌纤维羽状角，以研究纤维羽状角与肌肉大小之间的关系。从B型超声图像中，确定了肱三头肌的纤维羽状角和厚度，前者为肌束间隙回声与肱三头肌长头和内侧头腱膜回声之间的夹角，后者为脂肪-肌肉界面与肌肉-骨骼界面之间的距离。长头的羽状角范围为15至53度，内侧头为9至26度，这与已发表的以及本次关于人体尸体的数据相似或更大。正常受试者和健美运动员在肌肉厚度和羽状角方面存在显著差异（P < 0.01），肱三头肌长头（r = 0.884）和内侧头（r = 0.833）的肌肉厚度与羽状角之间均存在显著相关性，表明肌肉肥大涉及纤维羽状角的增加。
