Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.
College of Health and Life Sciences, Hamad Bin Khalifa University, Doha, Qatar.
Am J Physiol Regul Integr Comp Physiol. 2024 Jun 1;326(6):R472-R483. doi: 10.1152/ajpregu.00272.2023. Epub 2024 Apr 1.
The role of muscle mass in modulating performance and perceived fatigability across the entire intensity spectrum during cycling remains unexplored. We hypothesized that at task failure (T), muscle contractile function would decline more following single- (SL) versus double-leg (DL) cycling within severe and extreme intensities, but not moderate and heavy intensities. After DL and SL ramp-incremental tests, on separate days, 11 recreationally active males (V̇o: 49.5 ± 7.7 mL·kg·min) completed SL and DL cycling until T within each intensity domain. Power output for SL trials was set at 60% of the corresponding DL trial. Before and immediately after T, participants performed an isometric maximal voluntary contraction (MVC) coupled with one superimposed and three resting femoral nerve stimulations [100 Hz; 10 Hz; single twitch ()] to measure performance fatigability. Perceived fatigue, leg pain, dyspnea, and effort were collected during trials. T within each intensity domain was not different between SL and DL (all > 0.05). MVC declined more for SL versus DL following heavy- (-42 ± 16% vs. -30 ± 18%; = 0.011) and severe-intensity cycling (-41 ± 12% vs. -31 ± 15%; = 0.036). Similarly, peak force declined more for SL following heavy- (-31 ± 12% vs. -22 ± 10%; = 0.007) and severe-intensity cycling (-49 ± 13% vs. -40 ± 7%; = 0.048). Except for heavy intensity, voluntary activation reductions were similar between modes. Similarly, except for dyspnea, which was lower for SL versus DL across all domains, ratings of fatigue, pain, and effort were similar at T between exercise modes. Thus, the amount of muscle mass modulates the extent of contractile function impairment in an intensity-dependent manner. We investigated the modulatory role of muscle mass on performance and perceived fatigability across the entire intensity spectrum. Despite similar time-to-task failure, single-leg cycling resulted in greater impairments in muscle contractile function within the heavy- and severe-intensity domains, but not the moderate- and extreme-intensity domains. Perceived fatigue, pain, and effort were similar between cycling modes. This indicates that the modulatory role of muscle mass on the extent of performance fatigability is intensity domain-dependent.
肌肉质量在调节整个强度范围内的运动表现和感知疲劳方面的作用仍未得到探索。我们假设，在任务失败（T）时，与双（DL）腿相比，单（SL）腿在严重和极强度下的肌肉收缩功能下降更多，但在中温和重强度下并非如此。在 DL 和 SL 斜坡递增测试之后，在单独的日子里，11 名休闲活跃的男性（V̇o：49.5 ± 7.7 mL·kg·min）在每个强度域内完成 SL 和 DL 循环直到 T。SL 试验的功率输出设定为相应 DL 试验的 60%。在 T 之前和之后，参与者立即进行等长最大自主收缩（MVC），同时进行一次叠加和三次休息股神经刺激[100 Hz；10 Hz；单收缩（）]，以测量运动疲劳性。在试验期间收集感知疲劳、腿部疼痛、呼吸困难和用力情况。在每个强度域内，SL 和 DL 的 T 没有差异（均> 0.05）。与 DL 相比，重（-42 ± 16%对-30 ± 18%；= 0.011）和严重强度（-41 ± 12%对-31 ± 15%；= 0.036）后 SL 的 MVC 下降更多。同样，重（-31 ± 12%对-22 ± 10%；= 0.007）和严重强度（-49 ± 13%对-40 ± 7%；= 0.048）后 SL 的峰值力下降更多。除了重强度之外，两种模式之间的自愿激活减少相似。同样，除了呼吸困难外，在所有强度域中，SL 均低于 DL，运动模式下的疲劳、疼痛和用力评分在 T 时相似。因此，肌肉质量的数量以强度依赖的方式调节收缩功能损伤的程度。我们研究了肌肉质量对整个强度范围内运动表现和感知疲劳的调节作用。尽管任务失败的时间相似，但与 DL 相比，SL 导致重和严重强度范围内的肌肉收缩功能障碍更大，但在中温和极强度范围内并非如此。两种运动模式下的疲劳、疼痛和用力感觉相似。这表明肌肉质量对运动疲劳性的调节作用取决于强度域。
