The match-play demands and physiological requirements of professional rugby league

King, Patricia Anne (2007). The match-play demands and physiological requirements of professional rugby league PhD Thesis, School of Human Movement Studies , University of Queensland.

       
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Author King, Patricia Anne
Thesis Title The match-play demands and physiological requirements of professional rugby league
School, Centre or Institute School of Human Movement Studies
Institution University of Queensland
Publication date 2007
Thesis type PhD Thesis
Supervisor Dr David Jenkins
Abstract/Summary Although a number of research groups have attempted to estimate the physiological demands of rugby league match-play in order to provide relevant data for the design of specific training programs, all have been subject to a number of limitations. The two studies that have used time motion analysis (TMA) were published before the introduction of influential rule changes and the findings from this previous research are arguably dated with regard to the contemporary demands encountered by professional rugby league players. Moreover, research is yet to compare contemporary TMA data with training programs presently used with professional rugby league players. In particular, it is not clear whether current training practices take account of the frequent bouts of very high-intensity activity that are believed to occur during passages of play and which can determine the outcome of a match. The primary aim of the present thesis was therefore to analyse the movement patterns specific to professional rugby league players during match-play (Study 1). A secondary aim was to identify the timing and frequency of the most highly intense periods of play (Study 2). The findings were then used to develop a highly specific training drill that would reflect the most physiologically demanding periods of the game. The physiological costs of this very high intensity activity reflecting the most demanding periods of a game were then examined in a modified drill and comparisons made between the costs of running alone versus running and tackling (Study 3). Furthermore, current training practices were assessed to determine whether they met the physiological demands identified through TMA (Study 4). Study 1 examined the movement patterns and physiological demands of specific positional groups (hit-up forwards, adjustables and outside backs) during competition using time motion analysis (TMA). There were significant (P < 0.05) differences between the distances covered by the three positional groups and it was found that players covered shorter distances than described in previous research. It was determined that the average work to rest ratio was 1:6 for the outside backs and hit-up forwards and 1:5 for the adjustables. However, the average work to rest ratios did not reflect the most demanding periods of the game; these included repeated high-intensity efforts interspersed by recovery periods of very short duration. These periods of repeated highintensity work often occurred at crucial phases of the game, where players were either attacking or defending the try-line. The patterns of movement during the repeated highintensity periods of play were different for each of the positional groups. The hit-up forwards generally sprinted short distances before completing a tackle or being tackled. The recovery durations between bouts of high-intensity exercise were generally quite short. The adjustables covered greater distances in the lead-up to the tackle and completed more lateral movements. They also had greater recovery durations between repeated high-intensity efforts than the hit-up forwards and this was reflected in a greater time spent standing, walking and jogging. The outside backs covered greater distances in the lead up to the tackle than both the hit-up forwards and the adjustables. They also had longer recovery durations between repeated high-intensity efforts than the hit-up forwards but spent less time standing, walking and jogging than the adjustables. The patterns of play revealed significant differences between the positional groups, particularly in regards to repeated high-intensity activities. It was concluded that in order to be prepared for the most highly intense periods of match-play professional rugby league players should adopt training that included the highest and lowest work to rest ratios and also included tackling. Study 2 assessed the frequency, duration and nature of repeated high-intensity efforts in rugby league using the TMA data from Study 1. Rugby league players are frequently required to tackle an opponent after sprinting to a contest. Due to the high physiological demands of contact, and it’s frequency in rugby league, the element of contact is considered to be a key component of match-play. ‘Repeated bouts of high-intensity exercise’ (HiEx) were examined in the video footage; HiEx described any period of match-play that included three or more sprints and/or tackles with a mean recovery between efforts of less than 20s. There were a number of significant (P < 0.05) differences in HiEx between the positional groups. The hit-up forwards (20.3 ± 1.5) completed a significantly (P < 0.05) greater number of HiEx bouts than the outside backs (12.0 ± 1.0). In addition, the hit-up forwards (3.8 ± 0.8) completed a significantly (P < 0.05) greater number of efforts within the HiEx bouts compared to the outside backs (3.2 ± 0.4) and the adjustables (3.1 ± 0.4). The duration of the HiEx bouts were significantly shorter for the outside backs (17.9 ± 5.4 s) compared to the hit-up forwards (24.8 ± 9.5 s) and the adjustables (21.4 ± 5.9 s). The outside backs also had significantly (P < 0.05) longer recovery periods both within and between HiEx bouts compared to the hit-up forwards and adjustables. The study identified that rugby league players complete large volumes of high-intensity work compared to athletes in other sports. It is concluded that the hit-up forwards in particular should have a significant focus placed on repeated high-intensity efforts during training. Training for all positional groups should reflect the frequency, content and duration of those HiEx bouts identified in the present study. A modified training drill was used in Study 3 to determine the physiological requirements of repeated bouts of high intensity activities and to estimate the energy costs of tackling. A cohort (n = 7) of professional rugby league players completed two test protocols. The initial six minute protocol involved three repeat sets of six sprints interspersed by a rest period of equal time to the exercise duration. The second six minute protocol involved both sprinting and tackling. The subjects were required to drive a tackle bag backwards for two metres in a standing tackle. Heart rate, blood lactate concentration and oxygen uptake data were recorded for the duration of the two protocols. No significant differences (P < 0.05) in heart rate, blood lactate concentrations and oxygen consumption were identified between the two trials, suggesting that for players required to only complete three or less repeated efforts in a single bout of high-intensity exercise (HiEx) during match-play, a running only drill during training would be sufficient to prepare them for the cardiovascular demands of competition. However, the pattern of changes over time tended to be different between trials for all measures. Further repeat efforts may have shown subsequent increases in the physiological cost of exercise for the tackle protocol compared to the running only protocol. These trends support the position that tackling places significantly greater physiological demands on players as the game progresses and when players are required to perform greater numbers of repeat sets. It is recommended that all positional groups, and especially the hit-up forwards, participate in more extensive repeat ‘sets of six’ (i.e. greater than four repeat sets) in order to prepare for the most physiologically demanding periods of match-play. Study 4 examined whether selected training drills simulated competition demands. Three in-season training drills (Ups and Backs drill, Grids drill and Game Play drill) were video recorded and compared to match-play data of equal duration from Study 1. It was found that players covered a significantly (P < 0.05) greater distance in all three training drills than for a match-play period of equal duration (with the exception of the outside backs in the game-play drill). It was also found that players spent a greater percentage of time completing high-intensity activities in all three drills compared to match-play. However, although the game-play drill most closely resembled match-play compared to the other two drills, overall none of the drills closely replicated the characteristics of match-play with regards to the match-play activities and movement patterns. As the findings from Study 3 have shown, there is a strong tendency for fullcontact to increase the physiological cost of an already high-intensity exercise drill, particularly as a function of time. The absence of, for example, tackling in the gameplay drill, may under expose players (particularly the hit-up forwards) to the highest demands of match-play. While injury prevention during training and simulated gameplay is essential and the benefits of avoiding collisions and contacts are clear, there may be value in coaches seeking to add in to game-play additional exercises that increase the physiological cost to that equivalent to the highest demands experienced in a match. This could involve, for example, static exercise against resistance or wrestling. The present series of investigations have collectively shown that professional rugby league players, particularly the hit-up forwards, engage in periods of very high-intensity exercise that often determine the outcome of critical phases of play. The data tend to support the notion that tackling, when combined with sprinting, is particularly demanding and that training may need to better prepare players for the most arduous passages of play.

 
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