Training effects of amortization phase with eccentric/concentric variations--the vertical jump

Abstract

The purpose of this study was to find if the performance of the vertical jump is improved by the result of increasing the force, velocity, and muscle adaptation(s). For the experiment, there were four groups (Gr): three groups did the training programs and the fourth group was the control group (CG). In order to establish improvements in force and velocity, the groups performed three variations using eccentric (Ecc) and concentric (Con) movement. Finally, the leg presses, squat jumps (SJ) and countermovement jumps (CJ) were used to determine the changes in the muscle adaptations before and after the training program. For measuring the force, four force transducers were used. In determining the velocity, a displacement transducer was used. A surface EMG was used to measure the muscle activations during all of the tests that were performed. After eight weeks of training, Gr 1 and Gr 2 improved the isometric force and the power during the Con. movement for the leg press. For the SJ, Gr. 1 and 2 increased their height, muscle activity, force, and power, but only group one improved the velocity. However, group three improved the isometric force and power for the leg presses, the squat jump and the countermovement jump. For both of the jumps, they also increased velocity, muscle activity and height. There were no changes observed for group four. Although the three combinations of Ecc/Con movements existed during the training program, the force, velocity and muscle adaptations increased, but not all of the improvements were of the same degree.