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

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 (NME_EMG and NME_MMG, respectively) across the velocity spectrum in children versus adolescents.

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°/s. PT, MP, EMG amplitude, and MMG amplitude were quantified during all muscle actions. NME_EMG and NME_MMG were quantified by expressing PT relative to EMG and MMG amplitude, respectively, for each muscle action.

PT, MP, NME_EMG, and NME_MMG 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°/s (P < 0.001) then decreased significantly from 240 to 300°/s (P < 0.001) for all groups.

Overall, regardless of velocity, the expression of PT relative to EMG and MMG amplitude (NME_EMG and NME_MMG, 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.