title: Asymmetry of force fluctuation during low and moderate intensity isometric knee extensions.
abstract: The purpose of this study was to investigate the asymmetry of force fluctuation during isometric knee extension at low and moderate intensities. 11 healthy men (M age = 21 yr., SD = 1) performed unilateral force matching tasks; sustained isometric knee extension at 20% and 30% maximal voluntary contraction (MVC). During the tasks, a mechanomyogram was measured by an accelerometer arrangement placed on the vastus lateralis. Although force fluctuation was not significantly different between the two legs at 20% MVC, it was higher in the left (weaker) leg than in the right (stronger) leg at 30% MVC. A significant difference in mean power frequency of the mechanomyographic signal between the two legs was also observed only at 30% MVC. These results suggest that the asymmetry of force fluctuation during isometric knee extension was not statistically significant at low intensity; however, it was significant at moderate intensity. These differences in force fluctuation between intensities might be influenced by different motor-unit firing rates in active muscle.
authors.affiliation: Department of Sports Science, Faculty of Sports Science, Kyushu Kyoritsu University, 1-8 Jiyugaoka, Yahatanishi-ku, Kitakyushu-city, Fukuoka 807-8585, Japan. monofinswim@gmail.com
authors.forename: Kazushige
authors.initials: K
authors.lastname: Oshita
authors.forename: Sumio
authors.initials: S
authors.lastname: Yano
mesh_terms: D000054:Acceleration; D001696:Biomechanical Phenomena; D004576:Electromyography / Q000379:methods; D005583:Fourier Analysis; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D007717:Knee / Q000502:physiology*; D008297:Male; D053580:Muscle Strength / Q000502:physiology; D052097:Quadriceps Muscle / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult