Changes in sarcomere lengths of the human vastus lateralis muscle with knee flexion measured using in vivo microendoscopy
Changes in sarcomere lengths of the human vastus lateralis muscle with knee flexion measured using in vivo microendoscopy
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DOI：
10.1016/j.jbiomech.2016.07.013
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发表时间：
2016-09-06
影响因子：
2.4
通讯作者：
Delp, Scott L.
中科院分区：
文献类型：
--
作者：
Chen, Xuefeng;Sanchez, Gabriel N.;Delp, Scott L.
Sarcomeres are the basic contractile units of muscle, and their lengths influence muscle force-generating capacity. Despite their importance, in vivo sarcomere lengths remain unknown for many human muscles. Second harmonic generation (SHG) microendoscopy is a minimally invasive technique for imaging sarcomeres in vivo and measuring their lengths. In this study, we used SHG microendoscopy to visualize sarcomeres of the human vastus lateralis, a large knee extensor muscle important for mobility, to examine how sarcomere lengths change with knee flexion and thus affect the muscle's force-generating capacity. We acquired in vivo sarcomere images of several muscle fibers of the resting vastus lateralis in six healthy individuals. Mean sarcomere lengths increased (p=0.031) from 2.84 +/- 0.16 mu m at 50 degrees of knee flexion to 3.17 +/- 0.13 mu m at 110 degrees of knee flexion. The standard deviation of sarcomere lengths among different fibers within a muscle was 0.21 +/- 0.09 mu m. Our results suggest that the sarcomeres of the resting vastus lateralis at 50 degrees of knee flexion are near optimal length. At a knee flexion angle of 110 degrees the resting sarcomeres of vastus lateralis are longer than optimal length. These results show a smaller sarcomere length change and greater conservation of force-generating capacity with knee flexion than estimated in previous studies. (C) 2016 Elsevier Ltd. All rights reserved.
