• The utilisation of the Rugby League Athlete Profiling battery for assessing the anthropometric and physical characteristics of rugby league players

      Twist, Craig; Highton, Jamie; Moss, Sam; Dobbin, Nicholas (University of ChesterUniversity of Chester, 2020-01-18)
      The research described in this thesis used a standardised battery of tests called the ‘Rugby League Athlete Profiling (RLAP)’ battery for assessing the anthropometric and physical characteristics of UK-based rugby league players. The overall purpose of this research was to determine the utility of the RLAP battery, which involved establishing the use of RLAP across numerous professional clubs over a three-year period, determining the measurement properties of the tests included and investigating the factors associated with a change in the characteristics. An early version of the RLAP battery existed [called SPARQ] and was provided by the Rugby Football League with scope to alter this as part of this programme of research. Before determining if an alteration to the battery was required, it was essential to understand the tests that are currently used in rugby league for assessing the anthropometric and physical characteristics of players. As such, the systematic review initially sought to determine the volume of performance tests used in rugby league along with their measurement properties. Based on the results, it was evident that a shorter sprint distance (< 20 m) ought to be included in the battery. It was also clear that only one field-based method for measuring muscle strength was available, though had received minimal research. Furthermore, the review highlighted that no rugbyspecific intermittent running test had previously been used and that RLAP was the first battery to include such a test. Therefore, based on these results, the battery was rebranded to RLAP, which included a stature, body mass, a 10 m and 20 m sprint test, a rugby-specific intermittent test, a change of direction test, measures of lower- and whole-body power. With the RLAP battery confirmed, it was then used and the reliability (Chapter 4) and discriminant validity (Chapter 5) of its elements determined. Results indicated that the RLAP battery is reliable and does not require habituation. Furthermore, the calculation of the required change, which includes the worthwhile change and random error of each test, provides researchers and practitioners with a single value that can be used as an analytical goal to evaluate a true change in characteristics with confidence. All components of the RLAP battery (except 10 m sprint time) possessed adequate discriminant validity between youth, academy and senior rugby league players, suggesting this battery can accurately distinguish between playing standards. As noted in above, the review highlighted a rugby-specific intermittent test has yet to be established in the literature before its inclusion in the RLAP battery. Whilst it appeared to be suitable and, based on Chapters 3 and 4, is reliable and possesses discriminant validity, the test itself had received no previous attention. Given the novelty of this test, it was unknown if this test was better associated with the responses to rugby league match performance and what the physiological responses were to this test. As such, Chapter 5 sought to determine the concurrent validity of this test and compare it against the traditional Yo-Yo Intermittent Recovery test level 1 (Yo-Yo IR1). The results indicated the association between prone Yo-Yo IR1 distance and the external, internal and perceptual responses to simulated match-play was improved when compared to the Yo-Yo IR1. Chapter 6 demonstrated that starting each 40 m shuttle in a prone position increases the internal, external and perceptual loads whilst reducing the total distance achieved. The degree of shared covariance between the prone Yo-Yo IR1 and Yo-Yo IR1 suggest the rugby-specific test provided insight into additional characteristics associated with rugby league performance. In studies that have reported on the anthropometric and physical characteristics, few have considered the multiple factors that might influence these with no studies conducted in rugby league. Chapter 7 sought to determine the complex interaction between anthropometric and physical characteristics that requires careful consideration by those involved in developing youth and academy athletes. The results also revealed a number of contextual factors such as season phase, league ranking, playing age and playing position that can influenced the change in characteristics over the course of a competitive season. The findings of this study highlight how some characteristics are impaired towards the end of the season, thus providing a rationale for considering in-season training loads and the application of short training interventions to off-set these negative changes. Based on negative changes in some anthropometric and physical characteristics towards the end of the year, Chapter 8 reported on the efficacy of two in-season sprint interval interventions for enhancing the physical characteristics of rugby league players. Furthermore, the study provided insight into the sensitivity of the RLAP battery for detecting changes in the characteristics of rugby league players. The results highlighted that two weeks of rugby-specific and running-based sprint interval training appeared affective for promoting the physical characteristics of rugby league players with minimal deleterious effects on wellness and neuromuscular function. Using the reliability statistics from Chapter 1, the mean change for prone Yo-Yo IR1 in the rugbyspecific group met the required change whilst changes approached this value for the running-based group despite contrasting loads. In all, this study demonstrated that sprint interval training that includes sport-specific actions is a suitable and effective training modality that can be used in-season. In addition, the result demonstrated how the prone Yo-Yo IR1 was sensitive to change across the intervention period whilst others were not sensitive to sprint interval training due to the lack of specificity. This thesis provides a thorough evaluation of the RLAP battery that can be used by researcher and practitioners to assess the anthropometric and physical characteristics of rugby league players. The battery is reliable and possess discriminant validity, while the prone Yo-Yo IR1 has concurrent validity and is sensitive to change during a lowvolume in-season training intervention. Overall, this thesis provides justification for the tests included and comprehensively examines the utility of this battery for assessing the anthropometric and physical characteristics of rugby league players. Practically, this battery of tests can be used by researcher and applied practitioners in rugby league with an understanding of the reliability, validity and sensitivity of the tests along with some factors that might influence the characteristics of players across a season.