title: Region-specific myoelectric manifestations of fatigue in human rectus femoris muscle.
abstract: BACKGROUND
  Anatomical properties between proximal and other regions within the human rectus femoris (RF) muscle are nonuniform. We aimed to clarify the possible region-specific myoelectric manifestations of fatigue within the RF muscle by using an advanced surface electromyography (SEMG) technique.
  
  
  METHODS
  Nine healthy men performed sustained contractions at 50% of maximal voluntary contraction until exhaustion during isometric knee extension and hip flexion. During these contractions, multi-channel SEMG was recorded from the RF by using 46 electrode pairs which cover most of the superficial area of the muscle.
  
  
  RESULTS
  Fatigue-induced SEMG, i.e., an increase in root mean square and a decrease in median frequency, was not uniform within the muscle during both tasks and was greater in proximal regions.
  
  
  CONCLUSIONS
  Our findings suggest that myoelectric manifestations of fatigue within the human RF muscle are localized, and proximal regions are more fatigable than other regions within this muscle.
authors.affiliation: School of International Liberal Studies, Chukyo University, Yagotohonmachi, Showa-ku, Nagoya 466-8666, Japan. wkohei@lets.chukyo-u.ac.jp
authors.forename: Kohei
authors.initials: K
authors.lastname: Watanabe
authors.forename: Motoki
authors.initials: M
authors.lastname: Kouzaki
authors.forename: Toshio
authors.initials: T
authors.lastname: Moritani
mesh_terms: D000328:Adult; D004566:Electrodes; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D006615:Hip / Q000294:innervation; D006801:Humans; D007717:Knee / Q000294:innervation / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018763:Muscle Fatigue / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology; D018709:Statistics, Nonparametric; D019415:Torque; D055815:Young Adult
keywords: Median frequency; Neuromuscular compartment; bi-articular muscle; high-density surface electromyography; multi-channel surface electromyography