The Tkatchev on the high bar is a release and re-grasp skill in which the gymnast rotates in a direction during flight opposite to that of the preceding swing. Since the release window is defined as the time during which the gymnast has appropriate linear and angular momentum to ensure the bar can be re-grasped, it was speculated that the release windows for this skill would be smaller than for dismounts that are less constrained. One senior male gymnast competing at national standard performed 60 Tkatchev trials. A four-segment planar simulation model of the gymnast and high bar was used to determine the release windows in 10 successful and 10 unsuccessful performances of the Tkatchev recorded using a Vicon motion analysis system. Model parameters were optimized to obtain a close match between simulations and recorded performances in terms of rotation angle (1 degree), bar displacements (0.01 m), and release velocities (1%). Each matched simulation was used to determine the time window around the actual point of release for which the model had appropriate release parameters to complete the Tkatchev successfully. The release windows for the successful trials were small compared with those of dismounts. The unsuccessful trials were associated with later release and later timing of the actions at the shoulders and hips.

In Australia, a significant proportion of homicides occur in a domestic context, many following an identifiable history of domestic violence. For this reason, many domestic violence homicides are considered to be preventable. Sector advocacy and policy reform has reframed domestic violence as a serious social issue. In keeping with international trends, domestic violence death review teams have been introduced in Australia. These review teams examine domestic violence homicides to identify systemic gaps in service responses to prevent future deaths. This article describes the operational Australian domestic violence death review teams and the Australian Domestic and Family Violence Death Review Network.

Objective: This study investigated the effect of brief static and dynamic stretching on spring-mass leg stiffness in a vertical bilateral hopping task. Method: 38 men and 18 women were randomly assigned to either a natural (NAT; n = 27), or maximal (MAX; n = 29) hopping group. NAT bounced at their self-selected stiffness and MAX were instructed to bounce as stiffly as possible. Hopping was performed at 2.2 Hz on a force plate. After each of four treatment conditions (no stretch, 30 s stretch, multiple (4 ) 30 s stretch, and dynamic stretch), subjects completed three  30 s bouts (2 minute rest periods) of hopping, in a counterbalanced crossover design. Stretches were performed on: gluteals, hamstrings, quadriceps and calves. Spring-mass leg stiffness was calculated as the ratio of peak vertical force to vertical displacement during ground contact. Results: The results revealed that men displayed greater leg stiffness than women (mean difference: 6.04 kN•m-1 ; 95% likely range: 1.94-10.13 kN•m-1), and that MAX produced higher stiffness values than NAT (mean difference: 10.93 kN•m-1 ; 95% likely range: 6.84-15.03 kN•m-1). Although there were no significant effects of treatment (p = 0.85) or time (p = 0.54) on leg stiffness, there was a significant treatment × time interaction (p = 0.015). Nevertheless, post hoc analyses were unable to identify where those differences were. Conclusion: Relative to control, the results of this study showed that brief static stretching or non task-specific dynamic stretching does not affect spring-mass leg stiffness during vertical bilateral hopping.