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A time-motion analysis of professional rugby league match-play Trish King a; David Jenkins a; Tim Gabbett b a School of Human Movement Studies, The University of Queensland, Brisbane b Brisbane Broncos Rugby League Club, Brisbane, Queensland, Australia Online Publication Date: 01 January 2009

To cite this Article King, Trish, Jenkins, David and Gabbett, Tim(2009)'A time-motion analysis of professional rugby league match-

play',Journal of Sports Sciences,27:3,213 — 219 To link to this Article: DOI: 10.1080/02640410802538168 URL: http://dx.doi.org/10.1080/02640410802538168

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Journal of Sports Sciences, February 1st 2009; 27(3): 213–219

A time–motion analysis of professional rugby league match-play

TRISH KING1, DAVID JENKINS1, & TIM GABBETT2 1

School of Human Movement Studies, The University of Queensland, Brisbane and 2Brisbane Broncos Rugby League Club, Brisbane, Queensland, Australia

Downloaded By: [Charles Sturt University Subscription Services] At: 05:17 4 February 2009

(Accepted 8 October 2008)

Abstract The aim of this study was to analyse movement patterns of professional rugby league players during matches played as part of Australia’s National Rugby League (NRL) competition. The movement patterns of one player from each of the three positional groups (hit-up forwards, adjustables, and outside backs) during three competition matches were examined using time–motion analysis. Positional groups differed in distances covered (P ¼ 0.001), and covered shorter distances than those described in earlier research. The mean exercise-to-rest ratio was 1:6 for the outside backs and hit-up forwards and 1:5 for the adjustables. However, such ratios did not reflect the most demanding periods of the game, which included repeated highintensity efforts interspersed with recovery periods of short duration. These periods of repeated high-intensity exercise often occurred at crucial phases of the game, when players were either attacking or defending the try-line. Furthermore, patterns of movement during repeated high-intensity periods of play differed among positional groups. To prepare for the most highly intense periods of match-play, professional rugby league players should adopt position-specific training that includes the highest and lowest exercise-to-rest ratios likely to be experienced in competition.

Keywords: Match analysis, positional differences, exercise-to-rest ratios

Introduction There is limited information on the match-play demands of professional rugby league players. In the first of two investigations, Meir and colleagues (Meir, Arthur, & Forrest, 1993) compared the demands placed on forwards and backs in general and examined differences in activity among props, hookers, half-backs, and wingers. The positions were considered representative of the different playing units. Twenty individual match-play activities were defined and the frequency of each activity plus percentage of mean total time in each activity were analysed. Two matches were analysed using one representative player from each positional group. Total distance covered by players was recorded and mean total distance ranged from 6530 m (prop) to 7921 m (half-back). Data from this study provided useful information on types and intensities of activity completed during rugby league match-play. However, the value of these data is now limited, as the study was completed before the introduction of important and influential rule changes. Of particular note is the 10-m rule that was introduced in 1994.

Since then, players have been required to retire 10 m from the point at which the ball is played when not in possession, a marked increase over the previous distance of 5 m. In a subsequent study, Meir and colleagues (Meir, Colla, & Milligan, 2001) examined the impact of the introduction of the 10-m rule change, and assessed how it had affected match-play. The study analysed two professional games using an identical technique to that used in the first study. Positional groups were compared with a particular focus on effects that the rule change might have had on training practices. Changes brought about by the 10-m rule indicated that an even greater demand was being placed on the aerobic capabilities of players. Furthermore, it was suggested that interval training reflecting the exercise-to-rest ratios identified in the study would be beneficial (Meir et al., 2001). However, data for the second study were collected while there was an unlimited interchange rule and the present demands on professional rugby league players are likely to be different. Importantly, all data were reported only as means and standard deviations, which could underestimate particular physiological requirements of

Correspondence: T. King, School of Human Movement Studies, The University of Queensland, Brisbane, QLD 4072, Australia. E-mail: [email protected] ISSN 0264-0414 print/ISSN 1466-447X online Ó 2009 Taylor & Francis DOI: 10.1080/02640410802538168


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some periods of match-play. Furthermore, although the data were collected from elite players at the time, it is considered by observers that professionalism in training and the speed of the game have increased markedly since 2001. Owing to the paucity of information on current match-play demands in professional rugby league football, the main aim of this study was to provide a comprehensive analysis of the demands of professional rugby league match-play for three positional groups. Time–motion analysis was used to identify potential differences in type, duration, and frequency of the various patterns and intensities of movement among positional groups. Time–motion analysis refers to the frame-by-frame examination of video footage of individual athletes during match-play and the recording of time-and-distance data on their movement patterns. Methods Time–motion analysis was undertaken for three matches completed as part of the 2005 National Rugby League competition at Suncorp Stadium, Brisbane, Australia. Ethics clearance from the University of Queensland and informed consent from all players were obtained before the start of the study. One player from each of three positional groups was studied during each of the three matches. The positional groups were: outside backs that included the full-back, wing, and centre positions; adjustables that included the half-back, hooker, five-eighth/ standoff, and lock/loose forward; and hit-up forwards that included props and second row players. Video recordings were made during each match using analogue video cameras (Panasonic). Three video cameras were used to record the movements of players, with one player from each positional group filmed during three games. Cameras were positioned in the stadium, on the half-way line, approximately 30 m above the field of play to cover the entire playing area. The zoom function of each video

camera ensured that an image of the player and a 10-m radius of his surrounds were maintained. This ensured that the player’s position on the field relative to the ground markings could be determined. Each player was videoed for the duration of each of the three games and this included all breaks in play and bench-time. Mean values for each player over three matches identified and accounted for differences in standard of the opposition, environment, and interpretations of the laws by referees. A catalogue of the activity descriptors used was based on previous research and is described in Table I. Video footage was analysed using a hand-notation game-analysis system to log frequency, distance covered, and duration of the activities. Categories of intensity from 0 (‘‘no effort’’) to 5 (‘‘greatest effort’’) were assigned to each of the activity descriptors. Time spent standing (Category 0), walking (Category 1), and jogging (Category 2) were considered to be low-intensity exercise. Striding and lateral movements (Category 3), sprinting (Category 4), and tackling (Category 5) were regarded as high-intensity exercise. Reliability Reliability of the video analysis was assessed by methods previously described by Hopkins (2000) using typical errors of measurement. Limits of agreement (95%) were also calculated after it was determined that the data had a normal distribution. For a normally distributed variable, the limits of agreement are +2.77 times the typical error. The 2.77 value comes from the standard deviation of the difference score (which is root2 times the typical error) multiplied by 1.96 (which includes 95% of observations of the difference score) (Hopkins, 2008). Reliability was established for total time (seconds) spent in each intensity category and frequency (n) of each discrete movement activity. Re-testing of three randomly selected video-recordings was made one

Table I. Abbreviations and descriptors of match-play activities used during time–motion analysis of professional rugby league players. Match-play activity

Definition

Standing Forward walking Backward walking Forward jogging Backward jogging Forward striding

No locomotor activity Walking forwards, where movement involved at least one foot being in continuous contact with the ground Walking backwards, where movement involved at least one foot being in continuous contact with the ground Jogging forwards, where movement involved a flight phase and minimal arm swing Jogging backwards, where movement involved a flight phase and minimal arm swing Striding forwards, where movement was similar to jogging but involved a longer stride length and a more pronounced arm swing Sprinting forwards, where maximal effort and stride length were observed Sideward (transverse) movement, including all movement activities that deviated from the antero-posterior axis The sequence of making a tackle or being tackled, from the point of first contact until the ball was played Any kick in general play including kick-off, kick to touch, chip-kick, punt, and field-goal

Forward sprinting Lateral movement Tackling Kicking


Time–motion analysis of professional rugby league month after the initial analysis was completed. The typical error of measurement (TE) as a percentage was calculated and the values for frequency of each movement activity ranged from 1.8% to 7.2% TE (mean ¼ 6.4%) and the limits of agreement (95%) ranged from +4.99 to +19.94 (mean ¼ +17.73). Values for total time spent in each movement activity ranged from 2.2% to 11.8% TE (mean ¼ 6.4%) and the limits of agreement (95%) ranged from +6.09 to +32.69 (mean ¼ +17.73). Values for frequency and time spent in each of the movement activities (mean ¼ 6.4% TE) showed similar reliability to previous studies in basketball (McInnes, Carlson, Jones, McKenna, 1995) and rugby union (Duthie, Pyne, & Hooper, 2003). Statistical analysis The mean + standard deviation for total time, frequency, distance covered, and duration were established for each of the activity descriptors and each of the intensity categories for the three positional groups. Exercise-to-rest ratios for the high-intensity exercise periods were also established. Differences in the variables among each playing position were identified by means of a one-way analysis of variance (ANOVA). As appropriate, Tukey’s post hoc test identified specific differences. All statistics were run on SPSS v11.0 for Windows with an alpha of 0.05 set a priori.

Results Distance Outside backs covered 6265 + 318 m and adjustables covered 5908 + 158 m during match-play. Both these values were greater (P ¼ 0.001) than the distance covered by the hit-up forwards (4310 + 251 m) (Figure 1). This was in part due to

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the total time spent on the field by the players in each of the positional groups. Some groups were interchanged more often than others, with the hit-up forwards generally interchanged at least once and more often twice in each game to give them recovery time after periods of intense exercise. In the present study, none of the outside backs or adjustables spent any time on the bench. However, the hit-up forwards spent approximately 21 min on the bench. To establish the relative distance covered (metres covered during game time), time spent on the bench was excluded from the analysis. There were no differences between the positional groups when relative distance was considered (Figure 1). The maximum distances covered during any single match were 6486, 6082, and 4579 m for the outside backs, adjustables, and hit-up forwards respectively. These maximum distance values are 3.5%, 3.0%, and 6.0% greater than the mean values of the three games. Time The hit-up forwards spent more time standing (P ¼ 0.001) and tackling (P ¼ 0.039) than the adjustables and outside backs but less time walking (P ¼ 0.001), jogging (P ¼ 0.04), and striding/making lateral movements (P ¼ 0.001). The hit-up forwards spent less time sprinting than the outside backs (P ¼ 0.001), while the outside backs spent more time standing (P ¼ 0.02) but less time walking than the adjustables (P ¼ 0.041) (Figure 2). Absolute time The values for absolute exercise time include all data from kick-off to half-time and then from the secondhalf kick-off until the completion of play, including injury-time and bench-time. The markedly shorter time (P ¼ 0.001) spent exercising during match-play by the hit-up forwards (3740 + 328 s) than the

Figure 1. Absolute and relative distances (m) covered by the three positional groups [outside backs (OB), adjustables (ADJ), hit-up forwards (HU)] in the first and second half and the whole match. Values are mean + s. {Significant difference (P 5 0.05) compared with hit-up forward. {Significant difference (P 5 0.05) compared with adjustable. #Significant difference (P 5 0.05) compared with outside back.


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Figure 2. The percentage (%) of time spent in each intensity category by the three positional groups [outside backs (OB), adjustables (ADJ), hit-up forwards (HU)]. {Significant difference (P 5 0.05) compared with hit-up forward. {Significant difference (P 5 0.05) compared with adjustable. #Significant difference (P 5 0.05) compared with outside back.

outside backs (5080 + 248 s) and adjustables (5080 + 248 s) can be explained by the greater time spent on the bench by the hit-up forwards. The outside backs and adjustables played for the entire games, completing *16.4% more exercise than the hit-up forwards. There were notable differences between the outside backs and hit-up forwards for time spent in each of the intensity categories. The outside backs spent less time participating in high-intensity activities in the second half than in the first half (718%, P ¼ 0.001). In the first half, the outside backs spent longer participating in high-intensity activities than both the adjustables (712%, P ¼ 0.04) and the hit-up forwards (736%; P ¼ 0.001). In the second half, both the outside backs and the adjustables spent more time participating in high-intensity activities than the hit-up forwards (731%, P ¼ 0.001 and 740%, P ¼ 0.001 respectively). The differences observed among the groups in the second-half were similar to those seen during the whole match, with the hit-up forwards spending 34% less time in high-intensity activities than the outside backs and 30% less time in highintensity activities than the adjustables. The outside backs spent less total exercise time completing high-intensity activities in the second half than in the first half (75%, P ¼ 0.045). In the first half, the outside backs spent a greater percentage of time in high-intensity activities than both the adjustables (74%, P ¼ 0.03) and the hit-up forwards (77%, P ¼ 0.018). In the second half, there were no differences among the positional groups for percentage of time spent in high-intensity activities. Values for the whole match show that the outside backs spent a greater percentage of time in high-intensity activities than the hit-up forwards (5%, P ¼ 0.01).

Relative time To establish the relative percentage of time players spent performing high-intensity exercise, time spent on the bench was excluded from the analysis. The percentage of time spent in high-intensity activities for the hit-up forwards increased by 3%. During the first half, the outside backs spent a greater percentage of time in high-intensity activities than both the adjustables (74%, P ¼ 0.039) and the hitup forwards (74%, P ¼ 0.04). In the second half and for the entire time spent on the field, there were no differences among the groups for percentage of time spent in high-intensity activities (Table II). Discussion The aim of the present study was to compare the match-play demands for three positional groups of professional rugby league players. The maximum distances reported for the outside backs, adjustables, and hit-up forwards were 6486, 6082, and 4579 m respectively. These values are lower than those reported previously (Meir et al., 2001), where forwards were observed to cover approximately 10,000 m and backs approximately 8500 m. This discrepancy could in part be due to differences in the methods for determining distance covered. Furthermore, it is possible that the players in the current study were more effective at completing tackles than those players studied by Meir et al. (2001). This would reduce the distance covered chasing the opposition in defence and the distance covered in attack. In the present study, the outside backs and adjustables studied were not substituted at any point during the three matches. Because of the nature of

Time–motion analysis of professional rugby league Table II. Absolute time (s), time in high-intensity exercise (s), absolute percentage of time in high-intensity exercise (%), and relative percentage of time in high-intensity exercise (%) for the first and second half and the whole match for players in the three positional groups (mean + s). Positional group Outside backs


Absolute time (s) First half 2599 + 198{ Second half 2481 + 49{ Match 5080 + 248{

Adjustables

Hit-up forwards

2599 + 198{ 2481 + 49{ 5080 + 248{

2096 + 226 1735 + 102 3740 + 328

Time in high-intensity exercise (s) 391 + 43# First half 500 + 41{*{ Second half 361 + 62{ 418 + 24{ Match 862 + 99{ 809 + 56{

319 + 36# 249 + 4{# 568 + 40{#

Absolute percentage of time in high-intensity exercise (%) First half 19.3 + 1.6*{{ 15.0 + 0.7{ 12.2 + 0.5# Second half 14.6 + 2.5 16.8 + 0.8 12.6 + 4.3 Match 17.0 + 2.1{ 15.9 + 0.4 12.4 + 2.1# Relative percentage of time in high-intensity exercise (%) First half 19.3 + 1.6*{{ 15.0 + 0.7# 15.2 + 0.1# Second half 14.6 + 2.5 16.8 + 0.8 18.1 + 7.3 Match 17.0 + 2.1 15.9 + 0.4 16.5 + 3.2 Notes: {Significant difference (P 5 0.05) compared with hit-up forwards. { Significant difference (P 5 0.05) compared with adjustables. # Significant difference (P 5 0.05) compared with outside backs. *Significant difference (P 5 0.05) compared with second half.

the high-intensity exercise completed by the hit-up forwards at elite standard, coaches generally use the majority of their permitted 12 interchanges for these players. The hit-up forwards in the present study spent a mean of 1248 s (20 min and 48 s) on the bench over the three games, with the time approximately equally split between the first and second halves of each match. When the percentage of time spent completing high-intensity activities was expressed relative to the total amount of exercise time (i.e. excluding bench time), there was little difference in time spent in high-intensity activities among the three positional groups. The values reported for the outside backs, adjustables, and hit-up forwards were approximately 17.0, 15.9, and 16.5% respectively. The percentage time spent by players performing low-intensity activities was therefore approximately 83.0, 84.1, and 84.5% respectively. These values are similar to those reported previously (Meir et al., 1993), where time in low-intensity activities was approximately 85.9 and 93.7% for forwards and backs respectively. The exercise-to-rest (high-intensity–low-intensity) ratio for both the outside backs and hit-up forwards was *1:6 and *1:5 for the adjustables. These values are lower than those previously reported for props (1:7), hookers (1:10), half-backs (1:12), and wingers (1:28) (Meir et al., 2001). This could be due in part

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to the classification of the positional groups, the ability of the players analysed (as players of a lower standard might not compete at such a high intensity), and differences in the methods used to assess movement activities. In the main, every 4 s of high-intensity exercise was followed by approximately 21 s of low-intensity exercise. These values are also lower than those previously reported; Meir et al. (2001) found that players exercised for 4 s and had between 30 and 80 s rest. Stoppages in play for injury time and kicks accounted for the longest periods of low-intensity exercise. These periods of exercise ranged from 1 to 302 s, with continuous periods of high-intensity exercise ranging from 1 to 35 s. The exercise-to-rest ratio reflects total high-intensity exercise versus total low-intensity exercise time but does not accurately reflect the most demanding periods or ‘‘bursts’’ of high-intensity exercise that were followed by little or no rest time. The longest periods of high-intensity exercise without rest were 27, 35, and 22 s for the outside backs, adjustables, and hit-up forwards respectively. Some passages of high-intensity play included striding, sprinting, tackling, and lateral movement for periods of up to 25 s, with rest periods where the players stood, jogged or walked for a short time (sometimes for little as 2–3 s) before repeating a high-intensity exercise lasting from 10 to 20 s. In the present study, time spent in an intensity category differed between the outside backs and hitup forwards for all categories, between the outside backs and adjustables for standing and walking, and between the adjustables and hit-up forwards for all categories except sprinting. The hit-up forwards spent more time standing and tackling than both the outside backs and adjustables. However, the hitup forwards spent less time jogging, striding/moving laterally, and sprinting than the outside backs and less time jogging and striding/moving laterally than the adjustables. It is difficult to compare the results of this study with those of previous research (Meir et al., 1993, 2001) as the movement descriptors and positional groups used across studies were different. Patterns of movement during the periods of highintensity exercise differed among the positional groups in the present study. The hit-up forwards, who generally played in the middle of the field, strode or sprinted over short distances (approximately 5–6 m) before becoming involved in a tackle. They then spent a short time (approximately 3–4 s) returning to the defensive line or moving laterally before completing another period of high-intensity exercise. After the bouts of high-intensity exercise, they spent longer standing still to recover sufficiently to perform more tackles. The adjustables were observed to cover a greater distance in the lead up to tackling


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(approximately 8–12 m) than the hit-up forwards; the adjustables were more commonly defending and attacking at the edge of the ruck, and often completed high-intensity bouts of exercise after the ball and the players involved in the play had travelled further laterally across the field. For example, they often tackled the opposition player who had received an off-load (a pass out of a tackle to a supporting player) and taken the ball wider, or had made a run to take the ball to the defensive line themselves. This is reflected in the greater time spent jogging and striding/moving laterally by the adjustables than the hit-up forwards. The outside backs generally covered a greater distance before being involved in a tackle, as they often chased down a player who had broken through the defensive line or ran around or through the defence before being tackled. The outside backs were also involved in retrieving opposition kicks and running the ball back as far as possible for positional advantage. This resulted in the outside backs spending longer sprinting than the adjustables and hit-up forwards. As the outside backs were positioned at the edges of the field, they also spent more time standing and walking forwards and backwards, as they moved with the defensive or attacking line during the hit-ups completed by the forwards in the middle of the playing field. Differences in movement patterns among positional groups need to be reflected in training practices. Furthermore, although players from each of the positional groups have been shown to spend most of their time in low-intensity activities, the brief periods of very high-intensity exercise place concomitantly high dependence on the anaerobic energy systems to resynthesize ATP (Brewer & Davis, 1995); a primary objective of training should therefore be to replicate these patterns of play to enable players to cope with the highest demands placed upon them during competition. The highly intense periods of activity identified in the present study often occurred at critical times during the game. Analysis found that long periods of high-intensity exercise accompanied by shorter periods of recovery for all three positional groups occurred when players were either closely attacking the opposition’s try line or defending their own try line. This could be due to the quick play-the-ball when teams are attacking, as they try to move the ball as fast as possible out of the tackle contest, in an attempt to take advantage of a disorganized defensive line. This rapid movement of the ball results in the attacking players having little recovery between hitups and runs towards the defensive line (either as ball carriers or decoy runners). In these circumstances, the defensive team also has a shorter recovery between high-intensity exercise

periods, as they must run up to the attacking line, make tackles and return to an onside position many times while the opposition remains in possession. Furthermore, when a team gains possession of the ball close to its own try line, it must attempt to move the ball as far up the field as possible within the limits of the set-of-six to prevent the opposition from being close to the try line after the changeover. The nature and the duration of the high-intensity exercise periods differed among the positional groups. Mean exercise time without rest was approximately 4 s; however, the longest high-intensity period without rest was 35 s. This suggests that while most of the energy required to perform the periods of high-intensity exercise is derived from the ATP-PC system and via anaerobic glycolysis, there will be some contribution from aerobic sources for the longer periods (O’Donoghue & King, 2004). It is therefore recommended that the full range of durations for periods of high- and low-intensity exercise is taken into consideration when designing training programmes. It is essential that training should prepare the players to cope with the most taxing elements of rugby league match-play, to ensure that the players are not under-prepared. The diverse nature of the patterns of high-intensity movement activities identified by the present study indicates that each group must prepare differently to meet the specific positional demands of match-play. Given that periods of high-intensity activities occurred at critical times during the match, players need to train at a sufficient intensity to ensure that they are prepared for the most intense periods of match-play. It should be noted that the present study was conducted on only one team competing in the NRL. As such, the physiological demands could reflect the playing style of that team. Further time–motion analysis studies that investigate more teams are warranted. In summary, the present study has shown that professional rugby league match-play requires players to complete frequent bouts of high-intensity activity separated by short bouts of low-intensity activity. It was also shown that there are marked differences in the demands of rugby league matchplay among the three positional groups (outside backs, adjustables, and hit-up forwards), especially in the type and frequency of high-intensity activities. Furthermore, the periods of high-intensity exercise identified in the present study suggest that the demands placed on players at critical times during a game are not best represented by mean values. Notably, as each positional group has unique roles and requirements during match-play, it is critical that these should be reflected in the design of novel training practices.

Time–motion analysis of professional rugby league Acknowledgements At the time of this study, the third author was employed by the Queensland Academy of Sport, Brisbane, Australia.

References


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Hopkins, W. G. (2000). Measures of reliability in sports medicine and science. Sports Medicine, 30, 1–15. Hopkins, W. G. (2008). A new view of statistics: Typical error of measurement. Online resource (available at: www.sportsci.org). McInnes, S. E., Carlson, J. S., Jones, C. J., & McKenna, M. J. (1995). The physiological load imposed on basketball players during competition. Journal of Sports Sciences, 13, 387–397. Meir, R., Arthur, D., & Forrest, M. (1993). Time and motion analysis of professional rugby league: A case study. Strength and Conditioning Coach, 1, 24–29. Meir, R., Colla, P., & Milligan, C. (2001). Impact of the 10-meter rule change on professional rugby league: Implications for training. Strength and Conditioning Journal, 23, 42–46. O’Donoghue, P., & King, S. (2004). Activity profile of men’s Gaelic football. Journal of Sports Sciences, 22, 514–515.

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