Electromyographic and Mechanomyographic Responses During Isokinetic Leg Extensions in Children Versus Adolescents

Purpose The purpose of this study was to examine peak torque (PT), mean power (MP), electromyographic (EMG) amplitude, mechanomyographic (MMG) amplitude, and neuromuscular efficiency from EMG and MMG amplitude (NMEEMG and NMEMMG, respectively) across the velocity spectrum in children versus adolescents.Methods Seventeen children (n = 8 males, n = 9 females) and 22 adolescents (n = 11 males, n = 11 females) participated. Participants completed maximal concentric isokinetic leg extensions at 60, 120, 180, 240 and 300(degrees)/s. PT, MP, EMG amplitude, and MMG amplitude were quantified during all muscle actions. NMEEMG and NMEMMG were quantified by expressing PT relative to EMG and MMG amplitude, respectively, for each muscle action.Results PT, MP, NMEEMG, and NMEMMG were greater for the adolescents than the children collapsed across sex and velocity (P <= 0.021). There were no significant differences for EMG amplitude (P >= 0.051), while MMG amplitude increased significantly from 60 to 240(degrees)/s (P < 0.001) then decreased significantly from 240 to 300(degrees)/s (P < 0.001) for all groups.Conclusion Overall, regardless of velocity, the expression of PT relative to EMG and MMG amplitude (NMEEMG and NMEMMG, respectively), in conjunction with measurements of torque and power production, may provide practitioners a unique method of examining growth and development-related augmentations in neuromuscular function during dynamic movements.