title: Neuromuscular changes associated with superior fatigue resistance in African runners.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa - jordan.santos@ehu.eus.
authors.forename: Yolande X
authors.initials: YX
authors.lastname: Harley
authors.forename: Jordan
authors.initials: J
authors.lastname: Santos-Concejero
authors.forename: Alan
authors.initials: A
authors.lastname: St Clair Gibson
authors.forename: Hugh
authors.initials: H
authors.lastname: Mullany
authors.forename: Karen A
authors.initials: KA
authors.lastname: Sharwoo
authors.forename: Sacha J
authors.initials: SJ
authors.lastname: West
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Noakes
authors.forename: Malcolm
authors.initials: M
authors.lastname: Collins
authors.forename: Ross
authors.initials: R
authors.lastname: Tucker
mesh_terms: D000328:Adult; D044383:Black People; D004576:Electromyography; D015444:Exercise; D006801:Humans; D008297:Male; D009046:Motor Neurons / Q000502:physiology; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D012420:Running / Q000502:physiology*; D044465:White People; D055815:Young Adult