title: The Electromyographic Threshold in Girls and Women.
abstract: The electromyographic threshold (EMGTh) is thought to reflect increased high-threshold/type-II motor-unit (MU) recruitment and was shown higher in boys than in men. Women differ from men in muscular function.
  
  
  
  Establish whether females' EMGThand girls-women differences are different than males'.
  
  
  
  Nineteen women (22.9 ± 3.3yrs) and 20 girls (10.3 ± 1.1yrs) had surface EMG recorded from the right and left vastus lateralis muscles during ramped cycle-ergometry to exhaustion. EMG root-mean-squares were averaged per pedal revolution. EMGThwas determined as the least residual sum of squares for any two regression-line data divisions, if the trace rose ≥ 3SD above its regression line. EMGThwas expressed as % final power-output (%Pmax) and %VO2pk power (%PVO2pk).
  
  
  
  EMGThwas detected in 13 (68%) of women, but only 9 (45%) of girls (p < .005) and tended to be higher in the girls (%Pmax= 88.6 ± 7.0 vs. 83.0 ± 6.9%, p = .080; %PVO2pk= (101.6 ± 17.6 vs. 90.6 ± 7.8%, p = .063). When EMGThwas undetected it was assumed to occur at 100%Pmax or beyond. Consequently, EMGThvalues turned significantly higher in girls than in women (94.8 ± 7.4 vs. 88.4 ± 9.9%Pmax, p = .026; and 103.2 ± 11.7 vs. 95.2 ± 9.9%PVO2pk, p = .028).
  
  
  
  During progressive exercise, girls appear to rely less on higher-threshold/type-II MUs than do women, suggesting differential muscle activation strategy.
authors.affiliation: 1 Brock University.
authors.forename: Devon
authors.initials: D
authors.lastname: Long
authors.affiliation: 1 Brock University.
authors.forename: Raffy
authors.initials: R
authors.lastname: Dotan
authors.affiliation: 1 Brock University.
authors.forename: Brynlynn
authors.initials: B
authors.lastname: Pitt
authors.affiliation: 1 Brock University.
authors.forename: Brandon
authors.initials: B
authors.lastname: McKinlay
authors.affiliation: 2 Liverpool John Moores University.
authors.forename: Thomas D
authors.initials: TD
authors.lastname: O'Brien
authors.affiliation: 1 Brock University.
authors.forename: Craig
authors.initials: C
authors.lastname: Tokuno
authors.affiliation: 1 Brock University.
authors.forename: Bareket
authors.initials: B
authors.lastname: Falk
mesh_terms: D000328:Adult; D002648:Child; D004576:Electromyography; D016552:Ergometry; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D009119:Muscle Contraction / Q000502:physiology; D010101:Oxygen Consumption; D052097:Quadriceps Muscle / Q000502:physiology*; D055815:Young Adult
keywords: child-adult differences; muscle activation; muscle function