Development and validation of microtechnology-based algorithms for quantifying collisions in rugby union

Rugby union requires players to perform high-intensity locomotor and contact efforts, interspersed with low-intensity activity. Locomotor efforts include accelerations, running and sprinting, while collision efforts include ruck, tackle scrum and maul events. Recent research has quantified the demands of Rugby Union using player-worn microtechnology that contains global positioning systems (GPS) and tri-axial microsensors including accelerometers, magnetometers and gyroscopes. To date, research has extensively reported the locomotor demands of Rugby Union match-play using GPS, documenting total distance covered, high-speed distance, accelerations and running efforts. However, there is a lack of research on the contact events of match-play. A number of authors have investigated the contact demands of Rugby Union using microtechnology and applying non-specific algorithms to determine the number of collision events in Rugby Union. However, two major limitations exist in this approach. Firstly, while these algorithms have been validated for other collision sports (i.e. Rugby League), the unique collision events of Rugby Union mean they are unsuitable for this sport. Secondly, the developed algorithms do not delineate among contact events (i.e. ruck, scrum and maul), resulting in an underestimation of the contact demands of Rugby Union and all collision events being considered equally demanding. Therefore, the total physical demands of Rugby Union match-play are being under reported. Based on the identified gaps in the literature, the purpose of this thesis was to 1) conduct a systematic review of the use of microsensors to quantify sport-specific movements and determine if such devices are potentially capable of detecting collision events in Rugby Union (Study 1), 2) develop a valid algorithm to detect scrum events in training and match-play (Study 2); and 3) develop an algorithm to determine ruck and one-onone tackle events in Rugby Union (Study 3). This program of research was subsequently brought together by the final study (Study 4), which applied the newly developed algorithms with existing methods to uniquely quantify the locomotor and contact demands from both winning and losing teams in 12 elite matches. Results of this research provides a novel insight into the contact demands of elite Rugby Union and additionally provide validated methods to delineate each collision type. Results of this research provide a detailed overview of total physical demands of Rugby Union and provide insight into the different locomotor and collision profiles of winning and losing teams. This research demonstrates a unique application of microsensors and specific algorithms to quantify the collision demands of elite Rugby Union training and matchplay. For the first time, the total locomotor and contact demands of elite Rugby Union match-play, including those of winning and losing teams have been documented. Performance staff can use this information to more effectively monitor the training loads of players and design sport-specific conditioning programs to prepare players for the most demanding passages of match-play.