A Kinematic and Kinetic Case Study of a Netball Shoulder Pass

The majority of studies analysing netball skills using force platforms have focused on reducing the risk of injury from compression and torsion forces on the knee and ankle joints during landing and pivoting. In this preliminary case study our aim was to investigate the efficacy of a combination of tools to describe the kinematic and kinetic mechanisms underlying the netball shoulder pass. The segmental movements of the netball shoulder pass were analysed from video and force platform data in order to develop a suitable methodology for use in a larger study. Peak vertical ground reaction force of 850 N was found to coincide with the point of maximum velocity of the centre of pressure, occurring 40 ms before ball release. The participant’s centre of pressure continued anteriorly for 40 ms after ball release. The wrist traveled in a linear path during the propulsion phases, maximising impulse to the ball. A large shear force also occurred in the anterior posterior direction coinciding with ball release due to friction between the left shoe and the force platform, resisting the forward momentum of the body. Negative acceleration of the upper limb following the propulsion phase reached a peak of 68.6 rad/s-2 for the arm and 82.4 rad/s-2 for the forearm. Peak shoulder deceleration torque was calculated at 4.1 Nm which was greater than during acceleration (1.6 Nm). The combination of kinematic and kinetic tools yielded a comprehensive analysis of the investigated skill. Future biomechanical studies may determine differences in skill execution between novice and professional players or variability in movement within a population of skilled netball players

Effect of whole-body mild-cold exposure on arterial stiffness and central haemodynamics: A randomised, cross-over trial in healthy men and women

Aortic pulse wave velocity (PWV) and augmentation index (AIx) are independent predictors of cardiovascular risk and mortality, but little is known about the effect of air temperature changes on these variables. Our study investigated the effect of exposure to whole-body mild-cold on measures of arterial stiffness (aortic and brachial PWV), and on central haemodynamics [including augmented pressure (AP), AIx], and aortic reservoir components [including reservoir and excess pressures (P ex)]. Sixteen healthy volunteers (10 men, age 43 ± 19 years; mean ± SD) were randomised to be studied under conditions of 12 C (mild-cold) and 21 C (control) on separate days. Supine resting measures were taken at baseline (ambient temperature) and after 10, 30, and 60 min exposure to each experimental condition in a climate chamber. There was no significant change in brachial blood pressure between mild-cold and control conditions. However, compared to control, AP [+2 mmHg, 95 % confidence interval (CI) 0.36-4.36; p = 0.01] and AIx (+6 %, 95 % CI 1.24-10.1; p = 0.02) increased, and time to maximum P ex (a component of reservoir function related to timing of peak aortic in-flow) decreased (-7 ms, 95 % CI -15.4 to 2.03; p = 0.01) compared to control. Yet there was no significant change in aortic PWV (+0.04 m/s, 95 % CI -0.47 to 0.55; p = 0.87) or brachial PWV (+0.36 m/s; -0.41 to 1.12; p = 0.35) between conditions. We conclude that mild-cold exposure increases central haemodynamic stress and alters timing of peak aortic in-flow without differentially affecting arterial stiffness