The effect of knee joint angle on the coactivation of prepubertal boys and adult males
Keywords: muscle length, electromyography, co-activation, prepuberty, knee
AbstractThe purpose of this study was to investigate the influence of knee joint angle on the maximum moment and activation level of the knee extensors and flexors for untrained pre-pubertal boys (n=25; age 9.8±1.1) and adult males (n=25; age 29.6±5.0). Three maximal isometric voluntary knee extensions and flexions were performed at 3 different joint angles (5%, 50% and 95% of the maximal range of knee flexion), while the integrated averaged electromyographic (iaEMG) activity of the vastus medialis (VM), vastus lateralis (VL), and long head of biceps femoris (BF) muscles were recorded. The results indicated that absolute and relative torque was higher in adults compared to children. Agonist activity was not affected in both groups by joint angles. Antagonist activity was higher in extreme angles in both groups and higher in children in all selected joint angle. These findings suggest that the joint angles caused a deficit in neuromuscular performance of children and it could be attributed to their higher antagonist activity.