title: Muscle activation of the quadriceps and hamstrings during incremental running.
abstract: BACKGROUND
  The aim of this study was to determine the patterns of responses for the electromyographic (EMG) amplitude vs. oxygen uptake ( V̇O2 ) relationships from muscles of the quadriceps femoris and hamstrings during incremental treadmill running.
  
  
  METHODS
  Twelve men volunteered to perform an incremental test to exhaustion while EMG signals were recorded from the vastus lateralis, vastus medialis, biceps femoris, and semitendinosus muscles. Polynomial regression analyses were used to determine the best model fit for the EMG amplitude vs. V̇O2 relationships.
  
  
  RESULTS
  There were significant (P < 0.05) increases in EMG amplitude across V̇O2 for the vastus lateralis (quadratic, R = 0.995), vastus medialis (quadratic, R = 0.997), biceps femoris (cubic, R = 0.999), and semitendinosus (linear, R = 0.992) muscles as well as the hamstrings-to-quadriceps ratio (cubic, R = 0.999).
  
  
  CONCLUSIONS
  These findings indicate that the patterns of responses for muscle activation vs. exercise intensity appear to be unique among muscles of the thigh.
authors.affiliation: Human Performance Laboratory, Exercise and Sport Science, University of Wisconsin-La Crosse, La Crosse, Wisconsin, 54601, USA.
authors.forename: Clayton L
authors.initials: CL
authors.lastname: Camic
authors.affiliation: Human Performance Laboratory, Exercise and Sport Science, University of Wisconsin-La Crosse, La Crosse, Wisconsin, 54601, USA.
authors.forename: Attila J
authors.initials: AJ
authors.lastname: Kovacs
authors.affiliation: Department of Kinesiology, University of Alabama, Tuscaloosa, Alabama, USA.
authors.forename: Evan A
authors.initials: EA
authors.lastname: Enquist
authors.affiliation: Department of Health, Exercise, and Sport Sciences, University of New Mexico, Albuquerque, New Mexico, USA.
authors.forename: Trisha A
authors.initials: TA
authors.lastname: McLain
authors.affiliation: Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.
authors.forename: Ethan C
authors.initials: EC
authors.lastname: Hill
mesh_terms: D000704:Analysis of Variance; D004576:Electromyography; D005080:Exercise Test; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D012420:Running / Q000502:physiology*; D055815:Young Adult
keywords: EMG amplitude; electromyography; exercise intensity; oxygen uptake; treadmill