Individual Control Strategies in Training: Myoelectric activity and recruitment strategies in the co-contraction training

Abstract

BACKGROUND: The literature in motor control has abundant evidence on within-/between-person variability when it comes to control strategies in several behaviors - which largely influences intervention outcomes. Despite being an intervention itself, strength training paradigms are yet to be analyzed beyond the average behavior. Based on myoelectric activity (EMG) analyses, this study emerges as a descriptive analysis on how the co-contraction training paradigm provides stimuli for strength training of knee extensors and flexors. AIM: Considering the potential large interindividual variability in muscle activation patterns during resistance training, we explored the co-contraction paradigm considering the individual characteristics. METHOD: Ten active male adults participated in two days of co-contraction training paradigm with their EMG activity collected (sartorius, biceps femoris long and short heads, semitendinosus, semimembranosus, rectus femoris, vastus lateralis and medialis and tensor fascia-latae). RESULTS: On average, participants recruit 36% of their maximum EMG amplitude, decay 0.41% per repetition but increase 7.45% between sessions. The training stimulated similarly the knee flexors and extensors EMG ratio of all participants. However, participants demonstrated different average muscle recruitment patterns with few individuals modifying, largely, their recruitment over repetitions/days. Between and within-variability in recruitment pattern was maintained throughout repetitions and days. CONCLUSION: Thus, the co-contraction training demonstrated sufficient muscle activation to be employed and evoked similar muscular recruitment between agonists and antagonists. To the best of our knowledge, this is a pioneer study encompassing the complexity of movement control in evaluating a strength training protocol.