Motor unit firing rates increase in prepubescent youth following linear periodization resistance exercise training.
Document Type
Article
Publication Date
9-2024
Identifier
DOI: 10.1007/s00421-024-05455-w
Abstract
PURPOSE: The purpose was to examine the effects of 8-weeks (3 days/week) of linear periodization resistance exercise training (RET) on neuromuscular function in prepubescent youth.
METHODS: Twenty-five healthy prepubescent youth (11 males, 14 females, age = 9.1 ± 0.8 years) completed the RET (n = 17) or served as controls (CON, n = 8). Isometric maximal voluntary contractions (MVCs) and trapezoidal submaximal contractions at 35 and 60% MVC of the right leg extensors were performed with surface electromyography (EMG) recorded from the leg extensors [vastus lateralis (VL), rectus femoris, and vastus medialis] and flexors (biceps femoris and semitendinosus). EMG amplitude of the leg extensors and flexors were calculated during the MVCs. Motor unit (MU) action potential trains were decomposed from the surface EMG of the VL for the 35 and 60% MVCs. MU firing rates and action potential amplitudes were regressed against recruitment threshold with the y-intercepts and slopes calculated for each contraction. Total leg extensor muscle cross-sectional area (CSA) was collected using ultrasound images. ANOVA models were used to examine potential differences.
RESULTS: Isometric strength increased post-RET (P = 0.006) with no changes in leg extensor and flexor EMG amplitude. Furthermore, there were no changes in total CSA or the MU action potential amplitude vs. recruitment threshold relationships. However, there were increases in the firing rates of the higher-threshold MUs post-RET as indicated with greater y-intercepts (P = 0.003) from the 60% MVC and less negative slope (P = 0.004) of the firing rates vs. recruitment threshold relationships at 35% MVC.
CONCLUSIONS: MU adaptations contribute to strength increases following RET in prepubescent youth.
Journal Title
European journal of applied physiology
Volume
124
Issue
9
First Page
2675
Last Page
2686
MeSH Keywords
Humans; Male; Female; Resistance Training; Child; Muscle, Skeletal; Isometric Contraction; Motor Neurons; Electromyography; Recruitment, Neurophysiological; Muscle Strength; Action Potentials
Keywords
Children; Cross-sectional area; Hypertrophy; Neural adaptations
Recommended Citation
Herda TJ, Holmes EA, Cleary CJ, et al. Motor unit firing rates increase in prepubescent youth following linear periodization resistance exercise training. Eur J Appl Physiol. 2024;124(9):2675-2686. doi:10.1007/s00421-024-05455-w
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