Harley Yolande X, Santos-Concejero Jordan, St Clair Gibson Alan, Mullany Hugh, Sharwoo Karen A, West Sacha J, Noakes Timothy D, Collins Malcolm, Tucker Ross
UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa -
J Sports Med Phys Fitness. 2016 Jul-Aug;56(7-8):857-63. Epub 2015 May 27.
An enhanced ability to resist fatigue has been proposed as one of African runners' performance superiority sources, although their fatigue resistance during sustained non-running-specific activities remain unclear. This study aimed to compare fatigue resistance during sustained isometric exercise between performance-matched African and European runners.
Thirty long-distance runners (16 African, 14 European) performed submaximal fatiguing sustained isometric knee extensions. Rectus femoris electromyographic (EMG) activity was measured, and the muscle was electrically stimulated to contract at the beginning and end of the test.
Time to task failure was greater for African than European runners (269±115 vs. 193±52 s, P=0.002; effect size [ES]=0.85, large effect). During the test, EMG amplitude increased less over time (P=0.031), and the left shift in the EMG frequency spectrum was less over time for the African runners (P<0.001). In addition, there was a lower relative reduction in stimulated force output from the first to the second stimulation in African runners (17.75±14.95 vs. 37.89±14.78%, P=0.006; ES=1.35; large effect).
These findings of greater fatigue resistance during non-running-specific activity and the associated muscle recruitment profile may contribute to the understanding of the physiology underlying endurance performance in African runners.
尽管非洲跑步运动员在持续的非跑步特定活动中的抗疲劳能力尚不清楚，但抗疲劳能力增强已被认为是他们表现优越的来源之一。本研究旨在比较在持续等长运动中，成绩相当的非洲和欧洲跑步运动员的抗疲劳能力。
30名长跑运动员（16名非洲人，14名欧洲人）进行了次最大疲劳性持续等长伸膝运动。测量股直肌肌电图（EMG）活动，并在测试开始和结束时对肌肉进行电刺激以使其收缩。
非洲跑步运动员的任务失败时间比欧洲跑步运动员更长（269±115秒对193±52秒，P = 0.002；效应量[ES]=0.85，大效应）。在测试过程中，非洲跑步运动员的EMG幅度随时间增加较少（P = 0.031），并且EMG频谱随时间的左移也较少（P<0.001）。此外，非洲跑步运动员从第一次刺激到第二次刺激时，刺激力输出的相对降低幅度较小（17.75±14.95%对37.89±14.78%，P = 0.006；ES = 1.35；大效应）。
这些关于在非跑步特定活动中具有更强抗疲劳能力以及相关肌肉募集特征的发现，可能有助于理解非洲跑步运动员耐力表现的生理基础。
