title: Relationships between the mechanomyographic amplitude patterns of response and concentric isokinetic fatiguing tasks of the leg extensors.
abstract: The purpose of the present study was to examine possible correlations between the b terms (slopes) form the log-transformed mechanomyographic amplitude (MMGRMS)-force relationships and the fatigue index calculated from 50 maximal concentric contractions. Forty healthy subjects (age = 21 ± 2 yr) performed isometric ramp contractions from 5% to 85% of their maximal voluntary contraction followed by a 50-repetition concentric fatigue protocol of the leg extensors, fatigue index (%) was calculated from the 50-repetitions. MMG was recorded during the ramp contractions from the vastus lateralis (VL) and rectus femoris (RF). The b terms (slopes) were calculated from the log-transformed MMGRMS-force relationships. Correlations were performed comparing the b terms from the MMGRMS-force relationships for the VL and RF with the fatigue index. Significant positive correlations were found among the b terms from the MMGRMS-force relationships for the VL (p = 0.007, r = 0.417) and RF (p = 0.014, r = 0.386) with the fatigue index. The b terms from the log-transformed MMGRMS-force relationships for the VL and RF may have reflected muscle fiber type composition and, thus, correlated with the fatigue index. This adds further support that the MMGRMS-force relationships may reflect muscle fiber type composition.
authors.affiliation: Neuromechanics Laboratory, Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence, KS, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Cooper
authors.forename: Trent J
authors.initials: TJ
authors.lastname: Herda
authors.forename: John P
authors.initials: JP
authors.lastname: Vardiman
authors.forename: Phillip M
authors.initials: PM
authors.lastname: Gallagher
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Fry
mesh_terms: D001696:Biomechanical Phenomena; D005221:Fatigue / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007866:Leg / Q000503:physiopathology*; D008297:Male; D055595:Mechanical Phenomena; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009213:Myography; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult