Effect of isoinertial power training with limited range of motion in isokinetic knee torque and mechanical parameters of vertical jump

Abstract

The purpose of the present research was to study the effect of a training program involving knee extensions on a limited range of motion (30o), under heavy loading (65% MVC in 45o knee angle) and at the maximum movement speed (power training) in the maximum isokinetic torque of knee extensors and selected mechanical parameters of the countermovement jump. The sample was 16 students of Democritus University of Thrace, Department of Physical Education and Sport Sciences without a record of injuries, who did not participate during the research into another physical activity program. The participants performed five repetitions of maximum isokinetic extension at 180°/sec and three countermovement jumps before and after a six-week power training program. An isokinetic dynamometer was used to record the isokinetic torque while a piezoelectric force platform was used to measure the ground reaction force for the calculation of the mechanical parameters of the countermovement jumps. For the statistical processing of the data, a T-test analysis was performed for paired observations in the values of variables before and after training. Statistically significant increases in the values of the average maximum torque and maximum torque were found. In contrast, no statistically significant difference was found in the parameters of the jump other than mechanical power. In conclusion, the significant increase in the torque of the extended knee muscles over a period of just six weeks is likely due to a combined increase in muscle activation and the normal cross-section of these muscles due to very large the limited range of movement during training. Moreover, the significant increase in the mechanical power of the vertical jump is likely due to the fact that the above training was carried out at the maximum possible speed of execution.