Comparison of Drop Jump and Resisted Squat Jump

Measuring maximum power an athlete can produce is key to developing proper strength and conditioning programs, assessing progress in injury recovery, and evaluating overall athleticism. A vertical jump action is a widely accepted way to assess power producing ability. Power production is dependent upon the force applied against resistance and the velocity of the movement. This resistance is in the form of drop height in a drop jump and external weight in a squat jump. The power can be observed either as the peak power produced at any instant during the movement or as the average power produced throughout a defined time period of the motion. In this investigation, subjects’ power producing abilities were tested in a drop jump and a squat jump through a range of levels of resistance. The resistances were based on percentage of the subjects’ individual anthropometric data set at 0-, 10-, 20-, 30-, 40-, and 50% of the subjects’ heights in the drop jump and 0-, 20-, 40-, 60-, 80-, and 100% of the subjects’ body weights for the squat jump. Objective #1 sought the optimal resistance level for both jumping movements in which maximum power production is possible. These movements are not without potential injury. Objective #2 assessed six variables through modeling to predict the risk of injury in the movements in the knees and lower back. The variables included the valgus angle and the corresponding internal abduction moment of the knee, the compression and shear forces at the L5/S1 vertebrae, the abdominal pressure, and the lower back muscle tension. The type of jump and the resistance level of the jumps proved to have an effect on the risk of injury. Objective #3 established a method to use the peak or average power obtained by one of the jumping movements at any resistance level to estimate the peak or average power at any resistance level in either jumping movement. This translation of performance assessment would allow an athlete to be assessed for power production in a preferred jumping movement to avoid the risk of injury, while predicting their power production in another movement