Desporto e Saúde, CIPER, Faculdade de Motricidade Humana, Universidade de Lisboa, Estrada da Costa, 1499-002, Cruz Quebrada Dafundo, Portugal.
Sport Lisboa e Benfica, Human Performance Department-Health Performance, Av. Eusébio da Silva Ferreira, 1500-313, Lisboa, Portugal.
Sci Rep. 2020 Oct 2;10(1):16433. doi: 10.1038/s41598-020-73433-1.
This study examined whether a knee flexor isometric contraction at 20% of maximal voluntary isometric contraction until exhaustion would alter the biceps femoris long head (BFlh) and semitendinosus (ST) active stiffness, assessed using ultrasound-based shear wave elastography. Twelve healthy individuals participated in 2 sessions separated by 7 days. Time to exhaustion was similar in both sessions (day 1: 443.8 ± 192.5 s; day 2: 474.6 ± 131.7 s; p = 0.323). At the start of the fatigue task, the ST showed greater active stiffness than the BFlh (p < 0.001), with no differences between days (p = 0.08). The ST active stiffness then decreased from 40% of the task time to exhaustion (- 2.2 to - 13.3%, p = 0.027) until the end of the task (- 16.1 to - 22.9%, p = 0.012), while no significant changes were noted in the BFlh (p = 0.771). Immediately after the fatigue task, a decrease in active stiffness was observed in the ST (- 11.8 to - 17.8%, p < 0.001), but not in the BFlh (p = 0.551). Results were consistent between the 2 testing sessions (p = 0.07-0.959). The present results indicate that fatigue alters the hamstring active stiffness pattern.
本研究旨在探讨在 20%最大等长收缩力下进行股四头肌等长收缩直至力竭，是否会改变使用基于超声的剪切波弹性成像评估的股二头肌长头（BFlh）和半腱肌（ST）的主动刚度。12 名健康个体参与了 2 次间隔 7 天的测试。两次测试中力竭时间相似（第 1 天：443.8±192.5 s；第 2 天：474.6±131.7 s；p=0.323）。在疲劳任务开始时，ST 的主动刚度大于 BFlh（p<0.001），但两天之间无差异（p=0.08）。然后，从任务开始的 40%到力竭时间，ST 的主动刚度下降（-2.2%至-13.3%，p=0.027），直至任务结束（-16.1%至-22.9%，p=0.012），而 BFlh 则无显著变化（p=0.771）。在疲劳任务后立即，ST 的主动刚度下降（-11.8%至-17.8%，p<0.001），而 BFlh 则无变化（p=0.551）。两次测试之间的结果一致（p=0.07-0.959）。本研究结果表明，疲劳改变了腘绳肌的主动刚度模式。
