Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary T2N 1N4, Canada.
Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary T2N 1N4, Canada; Department of Biomedical Sciences for Health, University of Milan, Milan 20133, Italy.
J Sport Health Sci. 2022 May;11(3):319-329. doi: 10.1016/j.jshs.2021.06.001. Epub 2021 Jun 21.
This study used downhill running as a model to investigate the repeated bout effect (RBE) on neuromuscular performance, running biomechanics, and metabolic cost of running.
Ten healthy recreational male runners performed two 30-min bouts of downhill running (DR1 and DR2) at a -20% slope and 2.8 m/s 3 weeks apart. Neuromuscular fatigue, level running biomechanics during slow and fast running, and running economy parameters were recorded immediately before and after the downhill bouts, and at 24 h, 48 h, 72 h, 96 h, and 168 h thereafter (i.e., follow-up days).
An RBE was confirmed by attenuated muscle soreness and serum creatine kinase rise after DR2 compared to DR1. An RBE was also observed in maximum voluntary contraction (MVC) force loss and voluntary activation where DR2 resulted in attenuated MVC force loss and voluntary activation immediately after the run and during follow-up days. The downhill running protocol significantly influenced level running biomechanics; an RBE was observed in which center of mass excursion and, therefore, lower-extremity compliance were greater during follow-up days after DR1 compared to DR2. The observed changes in level running biomechanics did not influence the energy cost of running.
This study demonstrated evidence of adaptation in neural drive as well as biomechanical changes with the RBE after DR. The higher neural drive resulted in attenuated MVC force loss after the second bout. It can be concluded that the RBE after downhill running manifests as changes to global and central fatigue parameters and running biomechanics without substantially altering the energy cost of running.
本研究采用下坡跑作为模型，探讨重复运动效应（RBE）对神经肌肉性能、跑步生物力学和跑步代谢成本的影响。
10 名健康的男性业余跑步者在 3 周的时间间隔内，以-20%的坡度和 2.8 m/s 的速度进行了两次 30 分钟的下坡跑（DR1 和 DR2）。在下坡跑前后以及 24 小时、48 小时、72 小时、96 小时和 168 小时后（即随访日），记录神经肌肉疲劳、慢速和快速跑步时的平地跑步生物力学以及跑步经济参数。
与 DR1 相比，DR2 后肌肉酸痛和血清肌酸激酶升高的减轻证实了 RBE。在最大自主收缩（MVC）力损失和自愿激活方面也观察到 RBE，DR2 导致跑后和随访日期间 MVC 力损失和自愿激活减弱。下坡跑方案显著影响平地跑步生物力学；在 DR1 后随访日，与 DR2 相比，重心位移和下肢顺应性增加，观察到 RBE。观察到的平地跑步生物力学变化并未影响跑步的能量成本。
本研究证明了在 DR 后 RBE 时神经驱动以及生物力学变化的适应性证据。更高的神经驱动导致第二次跑后 MVC 力损失减弱。可以得出结论，下坡跑后的 RBE 表现为整体和中枢疲劳参数以及跑步生物力学的变化，而不会显著改变跑步的能量成本。
