Original researchPositional demands of international rugby union: Evaluation of player actions and movements
Introduction
Time-motion analysis of player movements1 and notational analysis of player actions2 can provide insight into the demands of team sports. Time-motion analysis has been defined as “the quantification of movement patterns involved in sporting situations, thus providing speeds, durations, and distances of various locomotor patterns during the course of a game”.1 A definition of notational analysis is that it is “an objective way of recording performance so that key elements of that performance can be quantified in a valid and consistent manner”.3 Although time-motion analysis can be viewed as a subset of notational analysis, in the context of team sports notational analysis has typically been distinguished from time-motion analysis by a focus on recording player match behaviours and counts of activities as opposed to player movement patterns.
Rugby union coaches and physical conditioning experts have a keen interest in understanding the physical demands of the sport, in order to develop effective training regimes and enhance on-field performance. The published time-motion analyses of rugby4, 5, 6, 7, 8, 9, 10, 11, 12, 13 have, however, been based on small samples of matches (between 1 and 16) and therefore the resulting statistics may not be representative.1 Papers reporting the number of various activities performed by position via notational analysis have also been limited in terms of sample size. A paper published in 2005, which is among the most comprehensive yet published, described the numbers of match activities by position performed by 22 players over a series of 21 professional matches.2 Importantly, no studies have yet reported detailed positional statistics for either time-motion data or the number of physical activities performed by players in international rugby matches (tests), which represent the highest level of participation in the sport.
Another limitation in the existing time-motion and notational analysis papers reporting activities and work-rates of rugby players is that the analyses have not accounted for the fact that players were repeatedly measured over a series of matches. If the lack of independence between observations derived from repeated-measures study designs is not addressed, the statistics generated may lead to inappropriate inferences being drawn.14 Generalized linear mixed models (GLMMs) extend the capabilities of linear mixed models from normally distributed dependent variables to counts and rates, and can deal with observations that are not independent. GLMMs thus lend themselves to the study of injuries and physical performance in team sports where players repeatedly appear. Despite being powerful tools that have been applied in a range of scientific disciplines (e.g. 15, 16, 17), GLMMs have yet to be widely used in sport research.
The purpose of the current study was to present a breakdown by positional group of the movement characteristics and physical activities performed by international rugby players during test matches played from 2004 to 2010. The study contains a considerably larger sample of matches than has been reported for previous comparable studies of rugby union.
Section snippets
Methods
All players in this study were either members of the New Zealand national team (the All Blacks) or their opponents. Data on player actions were collected from 763 players, who made 3700 appearances (2700 appearances as starters and 1000 as either tactical substitutes or injury replacements) in 90 matches played from 2004 to 2010. Time-motion data were obtained for 27 of the matches. The study complied with the ethical guidelines for observational studies produced by AUT University, New Zealand.
Results
Fig. 1 shows a tree diagram representing the relative similarity of the positions based on their activities and the distances they cover at the various speed zones. Reading from right to left, positions are first grouped into forwards and backs (Numbers 1–8 versus Numbers 9–15), with very little similarity between the two groups overall. Forwards were aggregated into sub-groups of tight forwards and loose forwards. Clusters within the tight forwards consisted of props (Numbers 1 and 3), locks
Discussion
Part of the rationale for conducting time-motion and notational analyses of rugby players is to compare and contrast positional roles to enable effective grouping of players for coaching and/or selection purposes. Information about the requirements of the positions can also assist with assessment of player performance during matches. Our study contains the first comprehensive breakdown of the activities and movements of positional groups for international rugby matches in the professional era.
Conclusions
As noted in previous time-motion studies, rugby is a sport in which intermittent periods of moderate to high intensity activities (both stationary and locomotor) are interspersed with periods of lower intensity activity or rest. The current study is the first to describe the physical demands imposed on the various positions by international match play. A comparatively large sample size permitted us to clearly delineate positional roles. International rugby matches place specific demands on
Practical implications
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The large differences in movement patterns, contact loads and activities between positional groups imply the need for different conditioning and recovery programmes for the different groups. For example, forwards may, in general, require greater time to rest and recover after each match than backs given the greater contact loads they sustain.
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Players at international level can expect to run further at high speeds than when they play at lower levels, and should be conditioned for the greater
Acknowledgement
The authors gratefully acknowledge the work undertaken by Verusco Technologies Ltd. (Palmerston North and especially of the late George Serrallach, the Managing Director of Verusco, who died in August 2012. He will be greatly missed.) in collecting and providing the data for the project. No financial assistance was provided for the preparation of the manuscript.
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