Abstract
The vertical jump has been shown to be an effective tool in assessing neuromuscular fatigue. The two most common iterations of the vertical jump are the countermovement and squat jumps. This investigation sought to identify if differences exist between the two jumping strategies with regard to electromyography (EMG) and kinetics in a group of recreationally trained males. Twenty-two participants completed one experimental session, where three countermovement (CMJ) and three squat jumps (SJ) were performed using a counterbalanced within-subject design. Jump performance was evaluated with data obtained using a force platform. Additionally, EMG was collected on the vastus lateralis (VL), vastus medialis (VM), semitendinosus (ST) and medial gastrocnemius (MG). Greater EMG values were seen in the CMJ for ST as well as percentage of activation in the MG (p < 0.05). Increased values of mean force and mean power were observed in the SJ, while the CMJ showed greater peak and mean velocity. Greater jump heights in the CMJ were present as well (p < 0.05). These findings suggest that the increase in CMJ jump height due to the increase in propulsive velocity is not due to increases in knee extensors muscle activation.