Quantification of the demands of elite rugby union players and understanding the subsequent physiological and epigenetic responses : $$b an applied approach towards prescription and individualisation

Abstract

The development of effective training load monitoring tools has enabled key insights into elite rugby union players' training and game demands and significantly improved the physical management of players. Whilst the use of training load quantification methods is common practice in elite sport, in the scientific literature, little information is known about the training and periodisation strategies of professional rugby union clubs, and how this may change throughout a competitive season. Throughout a season, coaches and practitioners face frequent decisions on daily training sessions, team selection, and competition scheduling. Understanding the load imposed on players from training and competition informs and aids this decision making. These decisions are integral to the optimisation of repeated player performance throughout a season. Diagnostic tools provide another piece of the puzzle to support player management decisions. The integration of both diagnostic measures and workload quantification aids the understanding of the dose-response relationship between fatigue and physiological adaptation. Building an effective individualised training load monitoring system is key within an elite rugby union club. Currently, practitioners are exposed to vast amounts of information that can be collected on individual athletes, slowing and limiting the ability to make effective choices on players’ health and performance. There is a need to synthesise this process and optimise athlete monitoring without creating additional staff and player burden. This thesis aimed to explore the multitude of factors that may influence the optimisation of elite rugby union players and explored the reasons for variation between individual players. The first part of this thesis quantified the external training load demands throughout a competitive season and evaluated the stress-induced effects of acute and chronic rugby training and match-play. Data from Chapter 4 demonstrated a strategical variation in training load prescription throughout a competitive season and showed key differences in external load metrics between position and the match status of players. Chapter 5 assessed changes in performance measures, biomarkers and subjective wellness throughout a full professional season. Certain periods of the season reported significant deviations from baseline measures and associations were observed between GPS variables and measures of performance and biomarkers. iv The second part of the thesis explored novel circulating miRNA (ci-miRNA) biomarkers and their role in the observed variation between players in response to training. Chapter 6 revealed associations between specific ci-miRNAs and anthropometric and performance variables that are consistent with the current understanding of plausible biological mechanisms. Lastly, Chapter 7 revealed the variability in training-induced responses to preseason training and, reported associations between certain baseline ci-miRNA levels with the observed anthropometric and strength changes. In summary, this thesis emphasises that even within a team sport, managing individual players is crucial to optimising performance; a one size fits all approach is not appropriate. A consistent and effective monitoring system needs to observe both external load and measures of fatigue, in order to inform and support the decision making of practitioners. Additionally, there is a great potential for the use of epigenetic information to inform practitioners of player management processes. However, this research in an elite sport setting is very much in its infancy and caution should be taken trying to implement this strategy.