مرکز منطقه ای اطلاع رساني علوم و فناوري - THE ACUTE EFFECTS OF ISOMETRIC PRECONDITIONING CONTRACTION ON JUMPING PERFORMANCE

Abstract :

Performance and response of a muscle group to voluntary or electrically induced contraction are positively or negatively affected by its contractile history. The performance of a muscle can decrease after continuous contractions under the exhaustive influence of contractile history or can increase after potentiation-induced a couple of maximal or close to maximal preconditioning contractions. The aim of this study was to investigate acute effects of preconditioning contraction during isometric leg press followed by a standard warm-up on squat and countermovement jump heights. Twenty (7 female, 13 male) sport sciences faculty students (age; 22.1±2.07 years, height; 173.5±8.7 cm, weight; 68.9±10.2 kg, body fat percentage; 16.5±5.84 %) participated in this study. Pretest- posttest study design was used in this study and subjects completed squat and countermovement jump test before and after preconditioning contraction. Preconditioning contraction was performed on a seated leg press machine (knee flexion 135o) maximal isometric voluntary contraction for 5 s. Preconditioning contraction was performed with 3 maximal repetitions and 90 s rest intervals, after this 3 maximum repetitions 8 min passive recovery was given and then jump tests were performed. A paired sample T-test was used to determine differences between pretest and posttest values of squat and countermovement jump. Statistical analysis showed that no statistically significant differences between pre and post test for squat (p=0.13) and countermovement jump (P=0.83). According to the results, there are no differences between squat and countermovement jumping heights measured before preconditioning contraction and 8 min after preconditioning contraction. As a result of the preconditioning contraction applied in this research, acute increase was not found in squat and countermovement jumping performances. According to these results, it was concluded that this preconditioning contraction protocol did not increase jumping performance.