Biceps femoris long head sarcomere and fascicle length adaptations after 3 weeks of eccentric exercise training  

作　　者：Patricio A.Pincheira Melissa A.Boswell Martino V.Franchi Scott L.Delp Glen A.Lichtwark 

机构地区：[1]School of Human Movement and Nutrition Sciences,The University of Queensland,Brisbane,QLD 4072,Australia [2]Department of Bioengineering and Mechanical Engineering,Stanford University,Stanford,CA 94305,USA [3]Department of Biomedical Sciences,University of Padova,Padova 35122,Italy

出　　处：《Journal of Sport and Health Science》2022年第1期43-49,共7页运动与健康科学（英文）

基　　金：partially funded by a Company of Biologists Travelling Fellowship;partially subsidized by a grant funded by the Australian Research Council(Linkage program)in partnership with the Australian Sports Commission(LP140100260)。

摘　　要：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;ηp2=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 pas sive tension of muscle or connective tis sue adaptations.

关 键 词：HAMSTRINGS Nordic hamstring exercise Sarcomerogenesis 

分 类 号：G808.1[文化科学—体育训练]