Offence vs defence: Quantifying workload demands in professional Rugby Union

Abstract

Title: Offence vs defence: Quantifying workload demands in professional Rugby Union. Purpose: Rugby Union is a skill-based contact team sport demanding high levels of physical and tactical skill. Ensuring that training matches the physical requirements for match-play demands is, therefore, important for success. Many factors influence the workload demands of match-play, including positional differences and the type of play (offence or defence). This thesis encloses an original and innovative study that compares the locomotive and contact workload demands of offensive and defensive ball-in-play periods for professional rugby union match-play. Methods: Data were collected for 40 professional Rugby Union players across 14 games in the 2021 Super Rugby season. All participants wore GPS units (Apex Pro Pod, STATSport, Newry, NIR). Each match was filmed and coded using the Sportscode video analysis software package (Sportscode 12.4.3, Sportstec, Australia), where contact metrics and type of play (offence and defence) were identified throughout the match. GPS and Sportscode data were combined in a bespoke software package. Data were analysed with the Statistical Analysis System (On-Demand for Academics, version 9.04, SAS Institute Inc., Cary, NC, USA), using a generalised mixed-model procedure (Proc Glimmix) specifying a log link and a Poisson distribution that allowed for overdispersion. The effect magnitudes were assessed for 2 SD changes in predictors. Results: Most metrics showed small to moderate increases for forwards and backs when offence was compared to defence. Small to large decreases in locomotive metrics, and a very large increase in contacts was observed when comparing forwards to backs, on offence and defence. When the effect of match outcome was examined, small to moderate effects were observed for some metrics for forwards on defence and backs on offence. The effect of fatigue was moderate to very large across most metrics, for forwards and backs in offence and defence. Conclusion: Offensive periods of play demanded a decisively greater workload than defensive periods of play across most metrics for forwards and backs. Additionally, there was strong evidence that backs performed greater locomotive workload but less contacts compared to forwards in both offence and defence. When winning was compared to losing, there was good evidence that backs achieved greater values for most locomotive metrics on offence, whilst forwards achieved greater values for some metrics during defence. Understanding how workload demands vary between positions and types of play can aid practitioners in effectively replicating match demands, whilst observed differences in workloads between winning and losing can provide insight into outcome-oriented conditioning for each position.