Inter-university Laboratory of Human Movement Biology, UJM-Saint-Etienne, University of Lyon, EA 7424, F-42023, Saint-Etienne, FRANCE.
Faculty of Kinesiology, University of Calgary, Calgary, Alberta, CANADA.
Med Sci Sports Exerc. 2022 Nov 1;54(11):1947-1960. doi: 10.1249/MSS.0000000000002976. Epub 2022 Jun 23.
Performance fatigability is substantially greater when exercising in the severe- versus heavy-intensity domain. However, the relevance of the boundary between moderate- and heavy-intensity exercise, the gas exchange threshold (GET), to performance fatigability is unclear. This study compared alterations in neuromuscular function during work-matched exercise above and below the GET.
Seventeen male participants completed work-matched cycling for 90, 110, and 140 min at 110%, 90%, and 70% of the GET, respectively. Knee extensor isometric maximal voluntary contraction (MVC), high-frequency doublets (Db100), low- to high-frequency doublet ratio (Db10:100), and voluntary activation were measured at baseline, 25%, 50%, 75%, and 100% of task completion. During the initial baseline visit and after each constant work rate bout, ramp-incremental exercise was performed, and peak power output and oxygen uptake (V̇O 2peak ) were determined.
After the 70% and 90% GET trials, similar reductions in MVC (-14% ± 6% and -14% ± 8%, respectively, P = 0.175) and Db100 (-7% ± 9% and -6% ± 9%, respectively, P = 0.431) were observed. However, for a given amount of work completed, reductions in MVC (-25% ± 15%, P = 0.008) and Db100 (-12% ± 8%, P = 0.029) were up to 2.6-fold greater during the 110% than the 90% GET trial. Peak power output and V̇O 2peak during ramp-incremental exercise were reduced by 7.0% ± 11.3% and 6.5% ± 9.3%, respectively, after the 110% GET trial relative to the baseline ramp ( P ≤ 0.015), with no changes after the moderate-intensity trials ( P ≥ 0.078).
The lack of difference in fatigability between the trials at 70% and 90% GET, coupled with the greater fatigability at 110% relative to 90% GET, shows that exceeding the moderate- to heavy-intensity boundary has implications for performance fatigability, while also impairing maximal exercise performance capacity.
在剧烈强度和重度强度范围内运动时，运动疲劳的表现明显更大。然而，中等强度和重度强度运动之间的界限，即气体交换阈值（GET），与运动疲劳的相关性尚不清楚。本研究比较了在高于和低于 GET 时进行工作匹配的运动过程中神经肌肉功能的变化。
17 名男性参与者分别以 110%、90%和 70%的 GET 完成 90、110 和 140 分钟的工作匹配的自行车运动。在基线、25%、50%、75%和 100%的任务完成时，测量膝关节等长最大自主收缩（MVC）、高频双脉冲（Db100）、低频至高频双脉冲比（Db10：100）和自愿激活。在初始基线访问期间和每次恒定工作率回合后，进行斜坡递增运动，确定峰值功率输出和氧气摄取量（V̇O 2peak）。
在 70%和 90% GET 试验后，MVC（分别为-14%±6%和-14%±8%，P=0.175）和 Db100（分别为-7%±9%和-6%±9%，P=0.431）的相似降低。然而，对于完成的相同工作量，MVC（-25%±15%，P=0.008）和 Db100（-12%±8%，P=0.029）的降低在 110% GET 试验中比 90% GET 试验高 2.6 倍。与基线斜坡相比，110% GET 试验后，斜坡递增运动的峰值功率输出和 V̇O 2peak 分别降低了 7.0%±11.3%和 6.5%±9.3%（P≤0.015），而中度强度试验后没有变化（P≥0.078）。
70%和 90% GET 试验之间疲劳程度没有差异，而 110% GET 试验相对于 90% GET 试验的疲劳程度更高，这表明超过中等到重度强度边界对运动疲劳程度有影响，同时也会损害最大运动能力。
