A trampoline is a gymnastic apparatus that allows acrobats to perform jumps consisting of multiple somersaults with twists. The jumps comprise alternating contacts with the trampoline bed and flight phases. The contact phase is further divided into the landing, which lasts from the first contact with the bed to maximum bed depression, and the take-off, which lasts from the maximum bed depression to the last contact with the bed. During the contact with the bed, acrobats adjust their movement so that they are able to successfully perform the set jump in the air. The acrobats in the competition perform routines containing ten jumps, which are then scored by the judges. The total score consists of time of flight, horizontal displacement, execution and difficulty. In case of non-compliance with the rules, the competitor may also receive a deduction from the Chief Judge.
Our study involved 25 acrobats, both male and female, who are registered at the Slovenian Gymnastics Federation. Each acrobat performed two routines consisting of ten stretched jumps with different horizontal displacement. For each take-off position, we measured the contact times and pressure forces on the bed for the left and right foot separately and calculated the coordinates of the jumps. A T-test was used to determine the asymmetries between the left and right leg, whereas regression was used to determine the characteristics of horizontal displacement.
During a trampoline jump, the asymmetries that occur allow us to move across the bed and rotate accordingly in order to perform various elements in the air. In addition to the forces on the ground, the horizontal displacement along the bed is also influenced by contact times and other variables that were not measured in the course of this study. At each take-off, the acrobat adjusts his or her movement according to the preceding and succeeding jumps.
|
