Do the Neuromechanical Properties of Knee Extensors Influence the Height of the Squat Jump in Pre-Pubertal and Pubertal Children?

The purpose of this study was to determine differences in the neuromechanical properties of knee extensors and vertical jump height between pre-pubertal and pubertal children, as well as to investigate the influence of these properties on the performance of the children's squat jump (SJ). The sample consisted of 13 pre-pubertal and 13 pubertal children of both sexes. The vertical SJ, a maximal isometric voluntary contraction (MVC) of the knee extensors, concomitant with the electromyographic activity (EA) of the vastus lateralis (VL), rectus femoris, vastus medialis (VM), and biceps femoris were collected. We compared the neural-mechanical variables of the CVM as Maximal Force (FMax), EA, Rate of Force Development (RFD), Force Max (FMAX), Rise of Electromyographic Rate (RER), Electromechanical Delay (EMD), and Co-activation. The findings showed that during the MVC of the knee extensors of the pubertal children versus the pre-pubertal children, they presented the following characteristics: (a) higher muscle capacity EA, lower EMD, higher RER, and similar co-activation; and (b) higher RFD at the beginning of MVC. Regarding the performance in the SJ, the pubertal children presented higher performance than the pre-pubertal children. In addition, linear regression identified an influence of the EMD of the VL and VM muscles on the performance of the SJ. [ABSTRACT FROM AUTHOR]