The effects of different conditioning contraction protocols of post-activation performance enhancement on variables of eccentric phases and concentric phase of vertical jumps

Abstract

Purpose Investigation of the influence of different conditioning contraction protocols on the eccentric variables in terms depth of descent of body centre of mass at countermovement jump as well as capacity of muscle force, power, and velocity at countermovement jump, and depth jump, i.e., velocity at time of rebound both mentioned jumps. Methods In a sample of 29-students (age: 19.6 ± 0.8), 1 repetition maximum was determined by estimating 10 repetition maximum, to be stratified in a six-week workout. Static group practiced hold back squat at 120° for 12 seconds, dynamic group practiced back squat at 120° (x8) for 12 seconds, and combined group practiced 2 back squat at 120° and 2 seconds endurance (x2) for 12 seconds. Control group had a 6 to 8 hours of activity per week. After the pre-contractions, they continuously performed shock-plyometrics (50 cm box), triple jump and 5-meter sprint. Training load was 80% of 1 repetition maximum. Results A statistically significant increase (13.3, and 9.3%) was found in spontaneous descent of body centre of mass at static and dynamic group, unlike in combined and control group (4.4, and 5.5%). In variables force, power, and velocity eccentric phases of countermovement jumps, significant performance ranges of experimental groups from 5.9 to 13.3% were found, unlike in depth jump variables for which there was no significance. Concentric variable in terms velocity time of rebound countermovement jump exhibits significance for dynamic and combined groups in values (3.4, and 4.3%), i.e., same variable of depth jump for static, dynamic, and combined groups in values (2.0, 2.9, 4.1%, respectively; p≤0.05). Conclusion The most indicated increases in variable, velocity at time of rebound at both jumps, were observed after the dynamic loads, referring to sublimated eccentric and concentric manifestations of muscular effects.