Abstract:
Increasing evidence suggests that activation of muscle nerve afferents may inhibit central motor drive, affecting contractile performance of remote exercising muscles. Although these effects are well documented for metaboreceptors, very little is known about the activation of mechano- and mechanonociceptive afferents on performance fatigability. Therefore, the purpose of the present study was to examine the influence of mechanoreceptors and nociceptors on performance fatigability. Eight healthy young males undertook four randomized experimental sessions on separate occasions in which the experimental knee extensors were the following: 1) resting (CTRL), 2) passively stretched (ST), 3) resting with delayed onset muscle soreness (DOMS), or 4) passively stretched with DOMS (DOMS+ST), whereas the contralateral leg performed an isometric time to task failure (TTF). Changes in maximal voluntary contraction (ΔMVC), potentiated twitch force (ΔQtw,pot), and voluntary muscle activation (ΔVA) were also assessed. TTF was reduced in DOMS+ST (-43%) and ST (-29%) compared with CTRL. DOMS+ST also showed a greater reduction of VA (-25% vs. -8%, respectively) and MVC compared with CTRL (-28% vs. -45%, respectively). Rate of perceived exertion (RPE) was significantly increased at the initial stages (20-40-60%) of the TTF in DOMS+ST compared with all conditions. These findings indicate that activation of mechanosensitive and mechanonociceptive afferents of a muscle with DOMS reduces TTF of the contralateral homologous exercising limb, in part, by reducing VA, thereby accelerating mechanisms of central fatigue.NEW & NOTEWORTHY We found that activation of mechanosensitive and nociceptive nerve afferents of a rested muscle group experiencing delayed onset muscle soreness was associated with reduced exercise performance of the homologous exercising muscles of the contralateral limb. This occurred with lower muscle voluntary activation of the exercising muscle at the point of task failure.
摘要:
背景:越来越多的证据表明,肌肉神经传入的激活可能会抑制中枢运动驱动,影响远程锻炼肌肉的收缩性能。虽然这些效应对代谢受体有很好的记录,关于机械和机械伤害性传入对性能疲劳的激活知之甚少。因此,本研究的目的是研究机械感受器和伤害感受器对性能疲劳的影响。
方法:八名健康的年轻男性在不同的场合进行了四次随机实验,其中实验性膝关节伸肌是:a)休息(CTRL),b)被动拉伸(ST),c)用DOMS(DOMS)休息,或d)用DOMS(DOMS+ST)被动拉伸,而对侧腿进行了等距的任务失败时间(TTF)。最大自愿收缩(ΔMVC)的变化,增强的抽搐力(ΔQtw,锅)和自愿肌肉激活(ΔVA)也进行了评估。
结果:与CTRL相比,DOMSST(-43%)和ST(-29%)的TTF降低。DOMS+ST也显示出更大的VA降低(-25%vs-8%,分别)和MVC与CTRL(-28%和-45%,分别)。与所有条件相比,在DOMSST中TTF的初始阶段(20-40-60%),RPE显着增加。
结论:这些发现表明,使用DOMS的肌肉的机械敏感性和机械伤害性传入的激活会降低对侧同源运动肢体的TTF,部分是通过减少VA,从而加速中枢疲劳的机制。