Injuries in professional rugby union: a study of five year of injury data with training loads and travel as co-variates
Rugby union has one of the highest reported incidences of injury amongst all professional team sports given collisions and tackles are a fundamental part of the game. The overarching question addressed in this thesis was “what has been the effect of changing match demands and competition expansion on current injury incidence?” Analysis of in-season training and injury data from 2006 – 2010 for a Super 14 Rugby team enabled this question to be evaluated. The thesis literature review established that previous epidemiological studies from the Super Rugby competition were outdated and formed the basis for the injury epidemiological analysis in Chapter 2. The effect of changing match demands and competition expansion on current injury incidence were compared to existing data from the professional rugby union literature, showing a higher incidence of match-related injuries over the five seasons. Additionally a higher incidence of training-related injuries was reported with the reasons for this finding less clear. An efficient injury recording and reporting regimen, as well as differences in training specifics, could have accounted for the higher injury incidence seen in trainings sessions.
Training load is an independent, but potentially modifiable, risk factor for injury and was analysed against injury risk in Chapter 3. Few studies have focused on the temporal relationship of prior cumulative training and match load on injury risk, with most studies focusing on the ‘acute’ effect of load and injury. An injury prediction model published in 20101 and developed for rugby league provided the stimulus for analysing our injury data against measured training loads. Using a novel application of over-dispersed Poisson regression analysis, actual daily and prior cumulative training load were compared against injury risk, and expressed as a magnitude based inference for effect. The effects for actual daily training load were not unexpected, where a higher training load was associated with a higher injury incidence and a higher total number of days lost, adding to the existing evidence. However a reduction in training-related non-contact soft tissue injury incidence and total days lost following periods of typically high versus typically low cumulative load were surprising, supporting a protective effect most likely due to adaptation. This protective effect was not seen in the analysis of match-related injuries where higher prior loads resulted in an increased risk of contact injuries. Post-training physical and mental factors presumably explain this effect and highlight the importance of tapering into a match.
Travel across multiple time zones is a unique feature of this competition in-season, with the literature unclear on the effects of travel on injury risk. Analysis of location and travel duration across time zones against injury, with training load measurement in each location, was the basis for Chapter 4. The limited data did not provide clear outcomes for injury risk as a function of location or travel duration but a trend towards an increase in incidence of match-related noncontact soft tissue injuries post long-haul (>5 hours) travel was observed.
This thesis provides practical information that can be used by medical personnel and strength and conditioning staff involved with teams from collision sporting codes.