Abstract
The rate of injury in professional rugby union is high compared to that of other team sports. As such, the need for injury mitigation strategies is evident. One emerging approach is the appropriate management of player load, with multiple studies across different sports demonstrating the association between load and injury risk. The aim of this thesis, therefore, is to build upon the small amount of work undertaken in rugby union to further our understanding of this modifiable risk factor to aid governing bodies and club practitioners make informed decisions around player loading patterns.The first experimental study in this thesis (Chapter Three) shows that over an eleven-season period training volume per player per week has remained stable. Over the same period, training injury incidence has also remained stable. However, injury severity has risen dramatically, with an injured player in the 2017/18 season missing an average of 20 extra days absence compared to an injured player in the 2007/08 season. Chapter Four demonstrates the clear association between weekly injury burden and team performance, as well as between training load and injury burden. No clear associations between training load and performance were evident. Chapter Five examines some commonly used methods for calculating the acute:chronic workload ratio training load metric. This investigation revealed that in the case of rugby union, despite club-by-club variation, a coupled and exponentially weighted 3 to 14 day acute:chronic workload ratio was the best fit for modelling injury data. Using this load measurement, calculated from session Rating of Perceived Exertion (sRPE) data, Chapter Six outlines a clear association between low acute:chronic values and injury risk when examining all injury types and non-contact soft tissue injuries in isolation. Acute:chronic workload ratio values of 1.26 were associated with “likely” beneficial effects, compared to a median value of 0.82 for both all injury and non-contact soft tissue injuries. Chapter Seven reports the current landscape of monitoring in professional rugby union in England, with widespread variation in the value placed on load monitoring metrics by clubs as well as extensive differences in the methods used to capture those metrics. This study was used to inform the final study of this thesis by identifying a group of clubs using similar load monitoring measurement tools. Chapter Eight provides evidence that both sRPE and Global Positioning System (GPS) data show clear associations with injury risk when aggregated using the acute:chronic workload ratio. Despite this, this Chapter also suggests the minimal added value of using both metrics, with similar Area Under the Curve values achieved when modelling with the “total distance” GPS metric or sRPE metric alone.
In summary, this thesis outlines the importance of player load as a modifiable injury risk factor in professional rugby union, identifying some key methodological steps for maximising the utility of the data collected in practice, including differences between team and individual level data as well as differing methods for capturing the same training load measures. This thesis also explores the utility of multiple load measurement types spanning from basic measures of training volume to more complex internal (sRPE) and external (GPS) measurement. The findings of this thesis demonstrate a clear link between both sRPE and GPS training load metrics and injury risk, with low acute:chronic workload values associated with an increased risk. This study is the largest of its type across sport and demonstrates the potential utility of managing training load to reduce injury risk in professional rugby union.
| Date of Award | 20 Nov 2019 |
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| Original language | English |
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| Supervisor | Keith Stokes (Supervisor) & Sean Williams (Supervisor) |