The relationships between rugby ground pass accuracy and kinematic variables resulting from two different pelvic orientations

Introduction: Despite having been largely understudied, one of the crucial components of a team’s success in rugby is accurate passing. This study identified biomechanical correlates of the rugby ground pass and accuracy performance.Methods: Sixteen club players (height 1.77±0.04 m; mass 86.8±16.8 kg) undertook a combined total of 96 passes and their respective body kinematics were analysed concurrent with measurements of pass accuracy at 10 m. Two distinct types of body orientations were found to be utilised by the players: a side-on orientation (pelvic rotation >80 °) and a front-on orientation (pelvic rotation <80 °).Results: Side-on body orientation passes were more accurate than front-on body orientation passes (p<0.0001). Fair relationships were present between the pass accuracy and upper body and hip kinematics for the two distinct body orientations individually. However, no common relationships were observed between the different orientations.Conclusion: Therefore different strategies exist within players to perform the ground pass with varying grades of accuracy.Keywords: biomechanics, direct measuremen

A simulated rugby match protocol induces physiological fatigue without decreased individual scrummaging performance

Background: A rugby union game consists of 80 minutes of strenuous exertion. Forwards are required to participate in the arduous activity of scrummaging throughout a game.Objectives: The purpose of this study was to identify whether rugby-match simulated fatigue modified individual scrummaging technique and reduced performance.Methods: Twelve forwards (body mass 106.2±13.3 kg; stature 179.5±8.4 cm) had individual scrum kinetics and kinematics assessed prior to and following a protocol that simulated a rugby match. The simulated rugby match protocol required participants to run at various velocities and perform rugby specific tasks. Rating of Perceived Exertion (RPE) was assessed using a 6-20 Borg scale and Visual Analogue Scale (VAS). Blood lactate, heart rate and RPE were measured prior to, at mid-point and after the simulated game, while markers of muscle damage (blood creatine kinase activity (CK) and urea) were measured prior to and following the protocol.Results: RPE (p<0.0001) and VAS (p<0.0001) showed significant increases between the pre- and post-simulation values. Of the physiological markers, heart rate (p<0.0001) and blood urea concentration (p=0.004) increased following the match simulation. No significant differences were observed for blood CK (p=0.281), individual scrummaging forces (p=0.433) or in the kinematic variables following the protocol. While physiological fatigue and subjective ratings of physiological fatigue may develop during a rugby simulation, no differences were observed in peak forces or in body kinematics at peak force.Conclusion: Physiological fatigue does not influence individual scrummaging performance and technique

Analysis of balance and body positioning in ballerinas with different levels of skill

Ballet is an art that requires great skill and balance to achieve aesthetic performance. The aim of this study was to determine whether there were differences in the size of the base of support (BoS) and skill (using two previously identified indicators of aesthetic performance: back arch angle and leg separation angle) between two groups of ballerinas with different skill levels. Twenty one professional female ballerinas classed as Corps de Ballet dancers (≤ 2 years academy dancing experience; n=14) and Soloists (>2 years academy dancing experience; n=7) participated in this cross-sectional, descriptive study. All ballerinas performed three unassisted, standard ballet positions en pointe (retiré, arabesque and penché), each held for at least three seconds. Retro-reflective markers were attached to specific anatomical landmarks and tracked by a 12 camera system. The size of the BoS was calculated using a pressure platform. The BoS was significantly smaller for the Soloists than the Corps de Ballet dancers during arabesque (p=0.0239) and penché (p=0.0337) but not retiré (p=0.1131). A statistically significant, inverse correlation was found between BoS and age for all three positions: arabesque (r=-0.4948, p=0.0368) and penché (r=-0.6232, p=0.0099) and retiré (r=-0.5623, p=0.0151). There was no kinematic difference (back arch angle and leg separation angle) between the groups. Our study provides insight into the biomechanics of balance in retiré, arabesque and penché. A link exists between age, skill required for the task and size of the BoS. More experienced dancers may utilise strategies other than a large BoS to maintain balance.Keywords: Ballet, dancer, base of support, centre of mass, balance, 3D analysi