A biomechanical evaluation of kinematic variables of the soccer-style and conventional-style placekicks following a prescribed resistance/velocity overload training program
Danz, Mary Elizabeth
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The purpose of this investigation was to compare changes in specified kinematic variables of the placekick before and after the implementation of a six-week velocity/resistance overload training program. Specifically, ball velocities, hip and knee velocities, and hip and knee accelerations were investigated. Five Northern Illinois University varsity football placekickers were subjects. According to their percentage of participation in the training program, the subjects were categorized as highly trained (HT) or minimally trained (MT). Five pre- and posttraining trials of each subject performing a placekick were filmed with a high speed camera at 200 fps. The film was analyzed with a Numonics digitizer interfaced with an Apple 11+ computer. The five trials of each subject were averaged for representative pre- and posttraining values for each subject for each of the kinematic variables. A t. test for independent samples was performed on the delta scores to determine significant differences between the HT and MT groups in the above kinematic variables. Three subjects participated in over 60% of the workouts, and were designated as the HT group. The remaining two subjects were designated as the MT group. Delta scores of -.16 m/sec for the HT group and -3.24 m/sec for the MT group in resultant ball velocity were significantly different, favoring the HT group. Delta scores of vertical and horizontal ball velocities were not significantly different between the groups. The two groups did not differ in kicking and nonkicking velocities. However, significant differences in kicking hip and knee accelerations were evident between the groups. A delta score of 442.37 deg/sec2 for the HT group was significantly different from a delta score of -816.49 deg/sec2 for the MT group in kicking hip acceleration. A delta score of 1729.35 deg/sec2 for the HT group was significantly different from the delta score of -1080.81 deg/sec2 for the MT group in kicking knee acceleration. It was concluded that this six-week V/ROT program promoted maintenance of ball velocity and kicking limb angular accelerations while the subjects were not actively involved in kicking practice. The V/ROT program may be suitable for injured kickers to maintain ball velocity and kicking limb accelerations, depending on the location of the injury. However, this training program was not suitable for developing kicking and nonkicking limb velocities as they are utilized during the execution of a placekick.