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标题：Biceps femoris long head sarcomere and fascicle length adaptations after 3 weeks of eccentric exercise training
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作者：Patricio A. Pincheira ; Melissa A. Boswell ; Martino V. Franchi 等
期刊名称：Journal of Sport and Health Science
印刷版ISSN：2095-2546
出版年度：2022
卷号：11
期号：1
页码：43-49
DOI：10.1016/j.jshs.2021.09.002
语种：English
出版社：Elsevier
摘要：Highlights • Biceps femoris long head fascicle and sarcomere lengths increase after 3 weeks of Nordic hamstring exercise training. • Architectural adaptations occurred only in the distal portion of the muscle. • Increases in fascicle length in response to 3 weeks of exercise training were not the result of serial sarcomere addition. Background Eccentric exercise increases muscle fascicle lengths; however, the mechanisms behind this adaptation are still unknown. This study aimed to determine whether biceps femoris long head (BFlh) fascicle length increases in response to 3 weeks of eccentric exercise training are the result of an in-series addition of sarcomeres within the muscle fibers. Methods Ten recreationally active participants (age = 27 ± 3 years; mass = 70 ± 14 kg; height = 174 ± 9 cm; mean ± SD) completed 3 weeks of Nordic hamstring exercise (NHE) training on a custom exercise device that was instrumented with load cells. We collected in vivo sarcomere and muscle fascicle images of the BFlh in 2 regions (central and distal) by using microendoscopy and 3 dimension ultrasonography. We then estimated sarcomere length, sarcomere number, and fascicle length before and after the training intervention. Results Eccentric knee flexion strength increased after the training (15%; p < 0.001; η p 2 = 0.75). Further, we found a significant increase in fascicle length (21%; p < 0.001; η p 2 = 0.81) and sarcomere length (17%; p < 0.001; η p 2 = 0.90) in the distal but not in the central portion of the muscle. The estimated number of sarcomeres in series did not change in either region. Conclusion Fascicle length adaptations appear to be heterogeneous in the BFlh in response to 3 weeks of NHE training. An increase in sarcomere length, rather than the addition of sarcomeres in series, appears to underlie increases in fascicle length in the distal region of the BFlh. The mechanism driving regional increases in fascicle and sarcomere length remains unknown, but we speculate that it may be driven by regional changes in the passive tension of muscle or connective tissue adaptations. Graphical Abstract Image, graphical abstract
关键词：KeywordsenHamstringsNordic hamstring exerciseSarcomerogenesis