Over the last two decades, plyometric training has been extensively adopted by athletes, coaches and sport scientists with a primary aim to improve vertical jump height. The focus of these plyometric programmes has been to train the lower-extremity musculature in order to enhance jump performance. However, the lower-extremities are not the only contributing factor to vertical jump performance, as the use of an arm-swing during vertical jumping has also been shown to contribute to achieving maximum vertical jump height, yet training programmes for improving the arm-swing during the vertical jump are limited. Therefore, the primary aim of this thesis was to examine the full arm-swing mechanics during vertical jumping, and to then develop and assess the suitability of an upper-extremity plyometric programme for increasing both arm-swing kinematics and jump height. Firstly, a descriptive study was conducted to assess if an arm-swing countermovement was utilised during the vertical jump, which was deemed the prerequisite for using plyometric training to improve the arm-swing. Then an experimental study was conducted comparing vertical jumps performed with and without an arm-swing countermovement. The results showed that jumps performed with an arm-swing countermovement significantly increased mean peak shoulder angular velocity (ω) (+67.5 deg·s-1) and mean jump height (+ 6.2 cm) when compared to jumps performed using no arm-swing countermovement. During the final chapter of this thesis, a group of elite basketball players volunteered to participate in upper-extremity plyometric training aimed at increasing vertical jump height by training only the upper-extremities. Vertical jump height and full body kinematics were analysed using a 3 dimensional (3D) motion capture system, and key kinematic jump variables and various arm-swing performance measurements were collated both before and after a 4 week upper-extremity plyometric intervention. The use of upper-extremity plyometric training significantly increased the mean jump height (+ 7.2 cm), mean peak shoulder ω (+ 167.1 deg·s-1), mean peak frontal shoulder ω (+ 121 deg·s-1) and mean active range of motion at the shoulder joint (+ 5.3°), when compared to a control group. Furthermore, the use of a large active range of motion armswing during the arm-swing countermovement was shown to be the preferred arm-swing condition for increasing arm-swing kinematics. The increase in arm-swing kinematics and jump height after the 4 week upper-extremity plyometric programme was attributed to the participants’ improved ability to use the stretch-shortening cycle, elastic energy transfer system and stretch reflex system. Therefore, the use of upper-extremity plyometric exercises as part of a training regime for improving vertical jump performance should be advocated.

This study compared the motor performance of children identified with Developmental Coordination Disorder (DCD) with those of a matched group categorised as typically developing (TD). Based on the existing literature, vertical jumping was the task selected as it is a fundamental movement skill (Gallahue & Ozmun, 2002), and a single optimal coordination pattern has been shown to exist (e.g., Bobbert & van Ingen Schenau, 1998).Within the conceptual framework developed for this enquiry, jump height, the performance outcome, was the highest level variable. Level 2 variables described the centre of mass displacement at key instants during the jumping movement. Level 3 variables identified measures of velocity, force and power, which underpin the movement, and level 4 variables described the countermovement specific to this task. This provided a more thorough analysis than previously reported in DCD literature for jumping. The objective of this study was to identify possible mechanisms of DCD in order to advance the understanding of this impairment. A cross-sectional sample (n = 165) of males and females aged between 5 and 12 years was drawn from a school in Victoria, Australia. Using the Movement–Assessment Battery for Children (M-ABC), 62 children from the sample were identified as having DCD with total impairment scores below the 15th percentile for their age-band (Henderson & Sugden, 1992). From the remaining children assessed, who all scored above the 15th percentile, 62 were matched with the DCD group to form the TD group (n= 62). Participants performed three maximal vertical jumps, standing on a single forceplate. Each child’s best vertical jump was analysed using forceplate (700 Hz) and 2D sagittal kinematic data from a single camera video (50 Hz) capture. The results confirmed previous findings that DCD children jump lower than their TD peers, although there was a considerable overlap in motor ability between the groups. Peak VCOM occurred earlier in the jumping movement in the DCD group, when compared to the TD group. This meant a longer elapsed time from the instant of peak VCOM to take-off, which was attributed to coordination error. The earlier occurrence of peak VCOM in the DCD group could be explained by the lower shank angular velocity at take-off. In addition, the DCD group produced lower jump impulse and peak power. Further probing of the jump height data revealed an interesting relationship between age band and jump height that was gender specific. It was noted that for the DCD males, less than 1% of the variance found in jump height could be accounted for by age-band. In contrast, the explained variance for jump height by age-band was 24% for the TD males. The females showed similar relationships for jump height and age-band in both groups. It was thought that this may reflect physical activity avoidance caused by greater social pressures on boys to be good at sports (e.g., Parker & Larkin, 2003).In addition, a further analysis of the DCD group data was undertaken to compare those who had difficulties in dynamic balance and those who did not. In this analysis, body mass was found to have a significant effect on leg stiffness (Kleg), and when accounted for as a covariate, greater Kleg in the DCD group with dynamic balance difficulties was found. A possible explanation is that for the DCD group with dynamic balance difficulties, the transition from joint flexion to extension during the countermovement was problematic, and resulted in excessive muscle co-activation. This study provides some possible directions for further investigations into coordination issues for DCD children. The time elapsed from peak VCOM to take-off and the shank angular velocities at take-off were identified as key indicators of a poorly coordinated jump. High levels of Kleg reflected difficulties in the transition from joint flexion to extension during the countermovement in those DCD children with dynamic balance problems. Based on these key variables and others that differentiated between groups a more parsimonious conceptual framework is presented. For future enquiry, a more holistic approach for the study of children with such impairments is recommended. This includes exploring the environment these children are exposed to in order to gain a more thorough understanding of practice and learning effects. Understanding of differences in motor ability requires an expanded framework to include information on genetic and socio-cultural factors, and their impact upon important psychology, physical fitness, nutrition, body composition and physical activity parameters.

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The purpose of this study was to display increase in eccentric hamstring strength after 10-weeks training program. Secondly, if such an increase occurred, would this strength change result in altered landing kinetics and improved jumping performance? 27 recreational female athletes assigned into experimental (n = 14) and control (n = 13) groups. Baseline measures of landing kinetics were collected using a force plate, strength data and proprioceptive measurements were evaluated using an isokinetic dynamometer and vertical jump performance were determined by a jumping mat. Results indicated that NHST group increased their eccentric hamstring strength after eccentric strength training program (week-1 = 233.6&plusmn / 27.5, week-10 = 253.8&plusmn / 28.4 Nm/kgbw / p&lt / .05). The results demonstrated that there were significant differences in landing mechanics for NHST group. PVGRF (week-1 = 6.2&plusmn / 0.9, week-5 = 5.3&plusmn / 0.9 / p&lt / .05), PAPGRF (week-1 = 1.1&plusmn / 0.2 &amp / week-10 = 0.8&plusmn / 0.3 / p&lt / .05) and APImp results demonstrated significant differences in trained group (week-1 = 78.1&plusmn / 13.6 &amp / week-10 = 67.8&plusmn / 9.2 / p&lt / .05). NHST group exhibited significant increase in vertical jumping ability (week-1 = 0.25&plusmn / 0.0 &amp / week-10 = 0.27&plusmn / 0.0 cm / p&lt / .01). This study supported the following points: 1) increases in the eccentric hamstring strength were evident after NHST program, 2) the increases in isokinetic strength were sufficient to cause alterations in landing kinetics to decrease the applied joint forces, so the NHST program would be an influential factor in decreasing the lower extremity injuries, and 3) the increase in the efficiency of force transfer at the final take off phase of jumping contributed to a higher performance in vertical jump.

The purpose of this study was to investigate two different plyometric training techniques for increasing vertical jumping ability. Twenty-four female high school volleyball players were matched for height and weight and distributed equally among three groups. Each subject performed a vertical jump test, Margaria power test, Wingate bicycle test, and an isokinetic leg strength test prior to and following six weeks of training. Plyometric training significantly (p<.05) improved vertical jumping ability and some indices of leg strength and power. Weighted plyometrics did not enhance performance more than plyometrics alone. These data support the view that plyometric training with or without added weights enhances vertical jumping and leg power.