the intensity influence of perform one set half squat on vertical jump performance and muscle electrical activity in adolescent athletes

the purpose of this study was to determine the intensity influence of perform one set half squat on vertical jump performance and muscle electrical activity in adolescent athletes. the subjects were 12 adolescent boys athletes. the subjects performed one set of dynamic half-squat using low and high intensities (li= low intensity with 40% 1rm, hi= high intensity with 80% 1rm), and a control (c) warm up condition on randomized separating conditions over the course of different 3 days. after a 4 minutes post-protocols, the subjects completed a vertical jump test (vj). the electromyographic (emg) activity of quadriceps (qc) and hamstring (h) were recorded during the concentric phase of the jumps. a one way anova with repeated measures on the one factor was used to analyze the data. the results of this study indicated that the vertical jump height and qc emg activity had improved significantly (p ≤ 0.05) after li protocol compared to c. no significant differences were found among the repeated measures in h emg activity (p > 0.05). it is concluded that the use of a specific warm-up that includes half-squats, performed with low intensity, improves vj performance that seems to be associated with the neurological and intramuscular changes.