Biomechanical comparison of netball shooting technique: A six-week jump training intervention
Henderson, Melanie Ellen
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Accurate shooting is critical to the success of the netball team. Introducing the jump shot into the game of netball, seeks to provide shooters with an additional shooting tool when in the outer parameters of the shooting circle, off balance, or as a counteraction against a well-timed jumping defensive. Purpose: To quantify the effects of a six-week netball shooting intervention on shooting performance (measured via kinematics and accuracy) from a distance of three metres. In addition, to determine the anthropometric and functional performance measures with netball shooting accuracy. Methods: Eighteen premier one, two and three female netball players (mean age 21.6 ± 4.3 years, height 172 ± 4 cm and mass 71 ± 10 kg) were randomised into three intervention groups of six netball shooters: experimental (EXP); training control (TC); and pure control (PC). Performance tests included functional chest power, single leg vertical jump, double leg vertical jump, shooting accuracy from a distance of three metres. A full anthropometry profile plus wrist flexibility were also completed. Tests were performed at three separate testing occasions; pre (0 wks), mid (3 wks) and post-intervention (6 wks). Goal shooting accuracy was obtained by using a 1-4 ordinal grid system. Body kinematics were calculated from 2D video analysis. Means and standard deviations are presented with Cohen effect sizes for comparisons between and within groups for pre and post-intervention comparisons. ANOVA’s with repeated measures were used for pre, mid and post-intervention comparisons for netball shooting accuracy. A forward stepwise multiple regression was used for the prediction of shooting accuracy from anthropometric and functional performance measures. Results: At the pre-testing occasion, significant differences in the preparation phase of the standing shot were observed between the EXP and TC groups. The TC group spent significantly less time preparing to shoot (45.9% TC, 66.7% EXP). Significant differences were also apparent in the standing shot within the crouch phase at the pre-testing occasion between the EXP and TC group (32.1% TC, 25.9% EXP). Four angles varied between the standing shot and the jump shot, at the pre-test intervention for all 18 netball shooters. The maximum ankle angle within the crouch phase was significantly larger in the jump shot (117 ± 10°), compared to the standing shot (105 ± 13°). Similarly, the minimum angle of the knee within the crouch phase differed significantly between shooting techniques (124 ± 20° stand, 118 ± 22° jump), indicating a lower crouch to create impulse within the jump shot. The minimum hip angle (154 ± 10° stand, 150 ± 11° jump) and the shoulder angle at release (143 ± 15° stand, 139 ± 21.0° jump) were both lower within the jump shot technique. The EXP group experienced three positive changes in the standing shot compared with the TC group. There was an increase in wrist ROM within the execution phase, creating greater ball velocity at release. A greater height of release and COM jump height were also observed indicating that the EXP group had a higher point of release despite their physical height. Accuracy changes were observed within the EXP and TC groups after a six-week training intervention. No significant differences in accuracy were found between the three groups at the pre-intervention testing occasion. The six-week training intervention amplified the differences in shooting accuracy between the three groups at both the mid-intervention and the post-intervention. A log transformed predicted change analysis in accuracy, made differences between the groups apparent. Respectively, the jump shot change was largest in the EXP group with a predicted change of 5.4 shots, the TC shooters 2.7 shots and the PC group 1.3 shots. These findings indicate that the variability of the jump shot allowed for the greatest improvement in accuracy over a period of six weeks. Accurate New Zealand premier-one netball shooters were predicted by a greater thigh skinfold and a longer shooting hand. Swoosh shots in premier two netball players were predicted by the breadth of the femur, and premier three swoosh shots were 100% predicted through a combination of a greater subscapular skinfold, longer tibia and greater chest girth. Conclusion: A six-week jump shot training intervention substantially improved netball shooting accuracy from a distance of three metres, via changes in kinematics and motor control. Key words: Netball, Shooting, Anthropometry, Kinematics, Accuracy, Predictors and Basketball.