Human Performance Laboratory, Department of Physical Education, IB, São Paulo State University, UNESP, Av. 24A, 1.515, Bela Vista, Rio Claro, São Paulo, CEP 13506-900, Brazil.
Biomechanics Laboratory, Department of Physical Education, São Paulo State University, Rio Claro, São Paulo, Brazil.
Sci Rep. 2020 Nov 2;10(1):18809. doi: 10.1038/s41598-020-76008-2.
Fatigue can be defined as exercise-induced strength loss. During running, fatigue can be partially explained by repetitive low-intensity eccentric contractions-induced muscle damage (EIMD). Previous studies showed that a bout of downhill running (DR) attenuated subsequent EIMD. Thus, we tested if a 30-min DR bout would attenuate fatigue induced by subsequent 60-min level running (LR). Twenty-seven male college students were randomly allocated to an experimental (EXP) or a control (CON) group. All participants performed LR on a treadmill at 70% of the velocity (vVOpeak) corresponding to peak oxygen uptake (VOpeak). Only EXP performed a 30-min DR (- 15%) on a treadmill at 70% vVOpeak fourteen days before LR. Indirect EIMD markers and neuromuscular function were assessed before, immediately and 48 h after DR and LR. Knee extension isometric peak torque (IPT) decreased (- 36.3 ± 26%, p < 0.05) immediately following DR with full recovery reached 48 h post-DR. Muscle soreness developed (p < 0.05) immediately (37 ± 25 mm) and 48 h (45 ± 26 mm) post-DR. IPT and rate of torque development (RTD) at late phases (> 150 ms) from the onset of muscle contraction decreased significantly (- 10.7 ± 6.1% and from - 15.4 to - 18.7%, respectively) immediately after LR for the CON group and remained below baseline values (- 5.6 ± 8.5% and from - 13.8 to - 14.9%, respectively) 48 h post-LR. However, IPT and late RTD were not significantly affected by LR for the EXP group, showing a group x time interaction effect. We concluded that a single DR bout can be used to attenuate fatigue induced by a LR performed fourteen days after.
疲劳可定义为运动引起的力量下降。在跑步过程中，疲劳可以部分归因于重复的低强度离心收缩引起的肌肉损伤（EIMD）。先前的研究表明，一次下坡跑（DR）会减弱随后的 EIMD。因此，我们测试了一次 30 分钟的 DR 是否会减弱随后 60 分钟的平地跑（LR）引起的疲劳。27 名男性大学生被随机分配到实验组（EXP）或对照组（CON）。所有参与者都在跑步机上以对应峰值摄氧量（VOpeak）的 70%的速度（vVOpeak）进行 LR。只有 EXP 在进行 LR 前 14 天在跑步机上以 70% vVOpeak 进行了 30 分钟的 DR（-15%）。在 DR 和 LR 前后即刻和 48 小时评估间接 EIMD 标志物和神经肌肉功能。在 DR 后即刻（-36.3±26%，p<0.05），伸膝等长峰值扭矩（IPT）下降，48 小时后完全恢复。肌肉酸痛在 DR 后即刻（37±25 毫米）和 48 小时（45±26 毫米）发展（p<0.05）。从肌肉收缩开始的后期（>150 毫秒）的 IPT 和扭矩发展率（RTD）在 CON 组的 LR 后即刻显著降低（-10.7±6.1%和-15.4 至-18.7%，分别），并且在 LR 后 48 小时仍低于基线值（-5.6±8.5%和-13.8 至-14.9%，分别）。然而，EXP 组的 LR 对 IPT 和后期 RTD 没有显著影响，表现出组间时间的交互作用。我们得出结论，单次 DR 可以用于减轻 14 天后进行的 LR 引起的疲劳。
