عنوان مقاله [English]
This research is aimed to compare of the acute effects of voluntary contractions (PAP) at different intensities and times on explosive power, sprint and agility among football players. In this study, thirteen subjects with a mean age of 17/7 ± 0/63 years, height 167/9 ± 5/4 cm, weight 57/9 ± 6/9 kg and BMI 20/5 ± 2/3kg/m were selected as available samples. After obtaining the subjects 1RM with half squat movement. The protocols of warm-up without load, the half-squat %45, %65, %85 1RM after 4 minutes and the half-squat %45, %65, %85 1RM after 15 minutes were randomly held for each of variables of explosive power, sprint and agility during seven-session sampling, and Tests, 35 meters sprinting, sargent vertical jump and agility illinois were taken. Data were analyzed using analysis of variance with repeated measure (ANOVA). The results showed in the PAP acute effect with P≤ 0.05 there is no significant difference between explosive power players with varying intensities after 4 minutes but there is significant difference after 15 minutes in the intensities of 65% and 85% with p=0/046 and p=0/021 compared to warm-up protocol. Between the sprint of players in PAP effects there is a significant difference after 4 minutes of 65% with p=0/02 and after 15 minutes in the intensities of 65% and 85% with p=0/027 and p=0/025 compared to warm-up protocol. Between the agility of players in PAP after 4 minute at intensities of 65% and 85% and after 15 minute of 65% there was significant difference between the intensities. Generally, in postactivation potentiation (Voluntary contractions) acute effect especially after the 15-minute the time plays has more effective role in improving the sprint and power activities of athletes at moderate intensities and peak intensity and agility with moderate intensity.