Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.
Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
Am J Physiol Regul Integr Comp Physiol. 2021 Aug 1;321(2):R238-R249. doi: 10.1152/ajpregu.00286.2020. Epub 2021 Jun 30.
Neuromuscular (NM), cardiorespiratory, and perceptual responses to maximal-graded exercise using different amounts of active muscle mass remain unclear. We hypothesized that during dynamic exercise, peripheral NM fatigue (declined twitch force) and muscle pain would be greater using smaller muscle mass, whereas central fatigue (declined voluntary activation) and ventilatory variables would be greater using larger muscle mass. Twelve males (29.8 ± 4.7 years) performed two ramp-incremental cycling tests until task failure: ) single-leg (SL) with 10 W·min ramp and ) double-leg (DL) with 20 W·min ramp. NM fatigue was assessed at baseline, task failure (post), and after 1, 4, and 8 min of recovery. Cardiorespiratory and perceptual variables [i.e., ratings of perceived exertion (RPE), pain, and dyspnea] were measured throughout cycling. Exercise duration was similar between sessions (SL: 857.7 ± 263.6 s; DL: 855.0 ± 218.8 s; = 0.923), and higher absolute peak power output was attained in DL (SL: 163.2 ± 43.8 W; DL: 307.0 ± 72.0 W; < 0.001). Although central fatigue did not differ between conditions (SL: -6.6 ± 6.5%; DL: -3.5 ± 4.8%; = 0.091), maximal voluntary contraction (SL: -41.6 ± 10.9%; DL: -33.7 ± 8.5%; = 0.032) and single twitch forces (SL: -59.4 ± 18.8%; DL: -46.2 ± 16.2%; = 0.003) declined more following SL. DL elicited higher peak oxygen uptake (SL: 42.1 ± 10.0 mL·kg·min; DL: 50.3 ± 9.3 mL·kg·min; < 0.001), ventilation (SL: 137.1 ± 38.1 L·min; DL: 171.5 ± 33.2 L·min; < 0.001), and heart rate (SL: 167 ± 21 bpm; DL: 187 ± 8 bpm; = 0.005). Dyspnea ( = 0.025) was higher in DL; however, RPE ( = 0.005) and pain ( < 0.001) were higher in SL. These results suggest that interplay between NM, cardiorespiratory, and perceptual determinants of exercise performance during ramp-incremental cycling to task failure is muscle mass dependent.
神经肌肉（NM）、心肺和感知对使用不同量活动肌肉量的最大分级运动的反应尚不清楚。我们假设，在动态运动中，使用较小的肌肉量会导致外周 NM 疲劳（抽搐力下降）和肌肉疼痛更大，而使用较大的肌肉量会导致中枢疲劳（自愿激活下降）和通气变量更大。12 名男性（29.8±4.7 岁）进行了两次递增式踏车测试，直到任务失败：）单腿（SL）以 10 W·min 斜坡和）双腿（DL）以 20 W·min 斜坡。在基线、任务失败（后）以及恢复 1、4 和 8 分钟时评估 NM 疲劳。在整个踏车过程中测量心肺和感知变量[即，感知用力（RPE）、疼痛和呼吸困难的等级]。两次测试的运动持续时间相似（SL：857.7±263.6 s；DL：855.0±218.8 s；=0.923），并且在 DL 中达到更高的绝对峰值功率输出（SL：163.2±43.8 W；DL：307.0±72.0 W；<0.001）。尽管中央疲劳在两种情况下没有差异（SL：-6.6±6.5%；DL：-3.5±4.8%；=0.091），但最大自愿收缩（SL：-41.6±10.9%；DL：-33.7±8.5%；=0.032）和单收缩力（SL：-59.4±18.8%；DL：-46.2±16.2%；=0.003）在 SL 后下降更多。DL 引起更高的峰值摄氧量（SL：42.1±10.0 mL·kg·min；DL：50.3±9.3 mL·kg·min；<0.001）、通气（SL：137.1±38.1 L·min；DL：171.5±33.2 L·min；<0.001）和心率（SL：167±21 bpm；DL：187±8 bpm；=0.005）。在 DL 中呼吸困难（=0.025）更高；然而，在 SL 中 RPE（=0.005）和疼痛（<0.001）更高。这些结果表明，在递增式踏车至任务失败期间，NM、心肺和感知决定运动表现的相互作用取决于肌肉量。
