Concussion in Rugby Union and the Role of Biomechanics

Due to the physical and high-impact nature of rugby, head impacts can occur within the game which can result in concussion injuries as well as other moderate-to-severe head injuries 1. Concussion has been defined as “a complex pathophysiological process affecting the brain, induced by traumatic biomechanical forces”1 and was found to be one of the more common brain injuries throughout the world.2 This is particularly true in sport; it has been estimated that over half of all concussions are sports related.3 A systematic review of the incidence of concussion in contact sports found that rugby union has a higher incidence rate compared with other sports such as American football and soccer.4 Unlike other sports injuries, detecting a concussion is difficult as the neuropathological changes cannot be recognized on standard neuroimaging technology.5,6 \Therefore, if a player is suspected of having a concussion, they are removed from play for a Head Injury Assessment (HIA). The HIA is a standardized tool for the medical assessment of concussion injuries in rugby and aims to improve detection and patient education.7 The HIA assesses a range of degenerative concussive symptoms including memory, cognitive ability, balance and player discomfort. This concussion diagnosis protocol therefore relies heavily on side-line medical staff to identify if a player is exhibiting concussive symptoms. A major disadvantage to this is that concussion has a variable natural history, with transient, fluctuating, delayed and evolving signs or symptoms.8) This means that symptoms can take up to 48 hours to become apparent.8 It has therefore been acknowledged that the content of the HIA will be modified as the research around concussion diagnosis evolves.8 The reliance on side-line medical staff to accurately identify concussive symptoms means that there is a possibility a concussed player may remain on the field; this is one problem that biomechanical research into concussion is trying to overcome.  This study will give an overview of concussion in rugby union with a focus on incidence, severity and protection strategies. It will discuss current biomechanical research and further biomechanical research required in the area of concussion injuries in rugby union

THE KINEMATICS OF HEAD IMPACTS IN CONTACT SPORT: AN INITIAL ASSESSMENT OF THE POTENTIAL OF MODEL BASED IMAGE MATCHING

Model Based Image Matching (MBIM) has potential to assess three-dimensional linear and rotational motion patterns from multiple camera views of head impact events in contact sports. The goal of this study is to assess the accuracy of the MBlM method for estimating 6DOF head kinematics in a vehicle-cadaver impact scenario for which Vicon motion analysis data are available as an independent measure. A three camera view MBlM reconstruction yielded RMS errors between 0.14-0.26 mls for change in head linear velocities ranging from 0.56-5.70 m/s, and 0.27-1.38 rad/s for change in head angular velocities ranging from 6.1041 -90 rad/s. The results from this study indicate that the MBlM method is a useful approach for measuring the kinematics of head impacts in sport

A data assimilation approach to last millennium temperature field reconstruction using a limited high-sensitivity proxy network

The authors acknowledge support from the Climate Program Office of the National Oceanographic and Atmospheric Administration (NOAA grants NA18OAR4310420 to KJA, NA18OAR4310426 to JEG and FZ, and NA18OAR4310422 to GJH). GJH also acknowledges support from the NSF through grant AGS–1702423. JMK was partially supported by NSF grant AGS-1803946. JET and JMK acknowledge support from NSF grant #AGS-1602301 and Heising655 Simons Foundation grant #2016-05.We use the Northern Hemisphere Tree-Ring Network Development (NTREND) tree-ring database to examine the effects of using a small, highly-sensitive proxy network for paleotemperature data assimilation over the last millennium. We first evaluate our methods using pseudo-proxy experiments. These indicate that spatial assimilations using this network are skillful in the extratropical Northern Hemisphere and improve on previous NTREND reconstructions based on Point-by-Point regression. We also find our method is sensitive to climate model biases when the number of sites becomes small. Based on these experiments, we then assimilate the real NTREND network. To quantify model prior uncertainty, we produce 10 separate reconstructions, each assimilating a different climate model. These reconstructions are most dissimilar prior to 1100 CE, when the network becomes sparse, but show greater consistency as the network grows. Temporal variability is also underestimated before 1100 CE. Our assimilation method produces spatial uncertainty estimates and these identify treeline North America and eastern Siberia as regions that would most benefit from development of new millennial-length temperature-sensitive tree-ring records. We compare our multi-model mean reconstruction to five existing paleo-temperature products to examine the range of reconstructed responses to radiative forcing. We find substantial differences in the spatial patterns and magnitudes of reconstructed responses to volcanic eruptions and in the transition between the Medieval epoch and Little Ice Age. These extant uncertainties call for the development of a paleoclimate reconstruction intercomparison framework for systematically examining the consequences of proxy network composition and reconstruction methodology and for continued expansion of tree-ring proxy networks.Publisher PDFPeer reviewe

Analysis of ball carrier head motion during a rugby union tackle without direct head contact: A case study

Rugby union players can be involved in many tackles per game. However, little is known of the regular head loading environment associated with tackling in rugby union. In particular, the magnitude and influencing factors for head kinematics during the tackle are poorly understood. Accordingly, the goal of this study was to measure head motion of a visually unaware ball carrier during a real game tackle to the upper trunk with no direct head contact, and compare the kinematics with previously reported concussive events. Model-Based Image-Matching was utilised to measure ball carrier head linear and angular velocities. Ball carrier componential maximum change in head angular velocities of 38.1, 20.6 and 13.5 rad/s were measured for the head local X (coronal plane), Y (sagittal plane) and Z (transverse plane) axes respectively. The combination of a high legal tackle height configuration and visually unaware ball carrier can lead to kinematics similar to average values previously reported for concussive direct head impacts