Rugby league is a game that comprises high-intensity activities interspersed with short periods of low-intensity activity (5,8). During the course of a match, players are involved in multiple physical collisions, predominantly in the form of tackles (2-4). It is considered that these tackling encounters are a major cause of musculoskeletal injuries (2,3). Tackle injuries have previously been associated with front-on tackling, rather than from the side or from behind (7) and a general lack of skill from the tackler has been highlighted as a risk factor. Tackling requires maximal strength and technique to perform an effective tackle, which should be trained accordingly (7).
Posthumus and Viljoen (7) suggest that the safest and most effective method of executing a tackle is to shorten steps before contact, drive forcefully with the shoulder on the same side as the lead leg, and hit into the trunk. The tackler's anatomical site of contact should always be the shoulder, the spine should always be in a neutral straight position with natural lordosis, thus resisting front-on axial forces and sideways axial torques; the tackler's shoulders should be higher than his hips at the time of contact (7).
Although tackling technique is a skill that has received considerable attention, information regarding the types of tackles players execute and the activities performed before contact is currently not available in professional rugby league match play. Data that could identify a possible relationship between playing position and the types of tackles completed may inform injury risk for certain players and also allow coaches to develop specialist strength and conditioning drills to reduce those risks. The purpose of this study was to describe the nature of, and circumstances relating to the various types of tackles completed by various playing positions in professional rugby league during competition and consider the implications of these tackles with regard to injury risk and training methodologies across playing position.
Experimental Approach to the Problem
Video time-motion analysis was used to investigate the tackling demands of specific rugby league positional groups. It was hypothesized that the forwards would make a greater proportion of 3-man tackles from low-intensity activities, such as standing, walking, and jogging, whereas the backs would make more one-on-one tackles preceded by a sprint.
The movement patterns of 15 players from a professional rugby league club were recorded during 5 National Rugby League games played in Australia during the 2008 season. Games were all played at Suncorp Stadium, Brisbane. After consultation with the coaches, players were clustered into 3 positional groups (hit-up forwards, adjustables, and outside backs). Five players in each of the 3 positional groups were assessed. The associated players in these positions were hit-up forwards (prop and second row), adjustables (halfback, hooker, five-eighth, and lock), and outside backs (fullback, wing, and center). The subjects were informed of the risks and benefits and provided informed consent before the investigation. The research was approved by an ethics committee of The University of Queensland.
Video recordings were made using 3 cameras (Hitachi DZ-GX5060SW, Hitachi Ltd., Japan) positioned on stationary tripods. Cameras were positioned on the half-way line approximately 30 m above the playing field. This allowed full view of the entire playing field. Each camera operator followed 1 player for the entire duration of each match investigated.
Each player was filmed with a minimal radius of 10 m so as to allow a view of his surroundings and field position. Each player was filmed for the entirety of the match, including breaks in play and time on the bench. The filming of 5 matches allowed for the averaging of data for each grouped playing position, differences in environment, oppositional standard, and variations in refereeing.
The video footage was analyzed using a simple hand-notation game analysis system; frequency for each movement activity were recorded. Movement was coded as 1 of 8 speeds of locomotion (standing, forward walking, backward walking, forward jogging, backward jogging, forward striding, forward sprinting, and lateral movement). These codes have been further defined previously (5).
Tackles were assessed by recording the sequence of involvement (e.g., whether a player was the first, second, or third player to engage in the tackle), the area of initial body contact on the player being tackled (e.g., H—high; above waist or L—low; below waist), and the type of tackle (e.g., F—front-on tackle, S—side-on tackle, and B—tackle from behind).
Reliability of the time-motion analysis method was assessed by having another operator perform repeat analyses on one half (ca., 40 minutes) of footage from 1 player. Intertester reliability was assessed by comparing analysis files from the 2 coders for the first analysis, while comparing the repeated analyses for coders assessed intratester reliability. Each experimenter was denied knowledge of results by the other experimenters and approximately 4 weeks separated the first and second analyses for intratester reliability. The imprecision of the coding technique was assessed using the typical error of measurement (TE) (6). Previous studies have applied this method of reliability to time-motion analysis in rugby (1) and hockey (9).
Typical error of measurement calculations were based on 4 measurements (frequency, total time, relative time [%], and relative distance [%]) of the 10 key movement modes (standing, forward walking, backward walking, forward jogging, backward jogging, striding, sprinting, tackling, and lateral movement). The TE (%) values for inter and intracoder reliability ranged from 0.2 to 7.8 and 0.4 to 9.3%, respectively.
Data for frequency of tackling and frequencies of different locomotor activities are presented as mean percentages. Analysis of variance (ANOVA) was used to establish differences in the variables among playing positions. Residuals from the ANOVA were checked for normality. A difference between hit-up forwards, adjustables, and outside backs, resulted in a post hoc test (Tukey) being used to establish where the differences occurred. All statistics were run on SPSS v17.0 for Windows with an alpha of 0.05 set a priori.
Over the 5 games analyzed, players in the 3 positional groups completed the following number of tackles: hit-up forwards 166, adjustables 89, and outside backs 41. All positions were statistically significant (p < 0.05) in the total number of tackles performed in match play of the 5 games analyzed.
Player Order of Contact in Tackles
Of all tackles performed, the majority (46%) involved the observed defender being the first physical contact in the tackle. Hit-up forwards were the only playing group where this did not occur with 37% as first player and 39% as the second player in the tackle contest (Table 1) although this was not statistically significant. For the adjustables and outside backs, the tackle involvement order descended from high first player contact to second and third accordingly (54 and 33%; 13 and 63%; 29 and 7%, respectively). Hit-up forwards were involved in a higher percentage of tackles as the third player involved (24%) opposed to all other positions, suggesting greater involvement in tackles around the ruck (Figure 1).
Types of Tackles Performed
The most common tackle executed by all positional groups was the player being involved second in the tackle from a front-on position, contacting the body above the waist (19%). The second and third most common tackle involved the first person in the contact, front-on and low (16%), and then high (15%) (Table 2).
There was a significant difference in types of tackles among hit-up forwards and the adjustables and outside backs (p = 0.03). For the hit-up forwards, the 2 most common tackles performed were the first player in contact, front-on and low (22%), and second being the second player involved in the tackle front-on and high (19%). For both the adjustables and outside backs, 22 and 32% of the total tackles performed by the 2 groups involved being the first person in the tackle, front-on and high (22 and 32% for the adjustables and outside backs, respectively). Over half (52%) of the tackles made by the outside backs involved being the first player in contact when tackling from a front-on position. There were no tackles performed by the outside backs in which the players were the second or third player involved, either from behind or low.
Activities Before Tackling
For the adjustables and outside backs, the most common activity performed immediately before the tackles was sprinting (28 and 44%, respectively), whereas the most common activity recorded for the hit-up forwards before tackling was striding (36%). Although these tendencies occurred, there was no statistical significance. Striding was the second most frequent activity before tackling for the outside backs (24%), whereas the adjustables had the same percentage for striding and lateral locomotion (22%). Collectively, for all playing positions, players were found to most commonly stride and sprint immediately before executing a tackle. Hit-up forwards were involved in a greater percentage (30%) of low-intensity activities, such as standing, walking, and jogging before tackling compared to the adjustables (27%) and outside backs (15%).
The primary aim of this study was to describe the nature of and circumstances relating to the various types of tackles completed by various playing positions in professional rugby league competition. It was hypothesized that the nature of tackles and the activities preceding tackles would differ among playing positions. In support of our hypothesis, the forwards made a greater portion of 3-man tackles from low-intensity activities, such as standing, walking, and jogging, whereas backs made more one-on-one tackles from sprinting. From a practical perspective, these findings provide game-specific data to inform the training practices of rugby league strength and conditioning coaches.
Over the 5 games analyzed, the hit-up forwards were involved in nearly twice as many tackles as the adjustables and 4 times as many tackles completed by the outside backs. Moreover, the hit-up forwards had a tendency to perform a slightly higher number of tackles as the second player in contact. The adjustables and outside backs had a tendency to be involved in a higher number of tackles as the first player involved, compared to being second or third in a tackle (54, 33, and 13%; 63, 29, and 7%, respectively). The hit-up forwards were found to have a more even distribution of percentage of tackles over the 3 orders of contact; first, second, or third (37, 39, and 24%, respectively). From a tactical perspective, these findings have implications for the coaching of tackle involvement in different playing positions. Furthermore, the high numbers of tackles performed by the hit-up forwards highlights the different physiological demands for this positional group. Conditioning designed to improve performance in the hit-up forwards should include a significant amount of tackling, collisions, and wrestling.
This study has shown that the various positional groups do not share the same combinations of tackles (i.e., as to whether the player is the first, second, or third involved in the tackle, whether the tackle is made from the front-on, side-on, or behind position or whether contact is low or high on the ball-carrier). The hit-up forwards were the only players to consistently execute, what would be considered, a standard rugby league tackle; the first player tackling from the front and low to stop the opposition player, whereas the second defender tackles from the front and high to prevent the ball from being passed.
Most tackles made by the adjustables were from the front and above waist height and most were as the first in contact. The second most frequent tackle category for the adjustables involved tackling from the front and high as the second player involved in contact. The outside backs were found to be involved mostly as the first person in a front-on tackle, predominantly tackling above the waist. In addition, outside backs were required to complete more one-on-one tackles, with fewer supporting defenders available. The present data show that the first defender generally makes a front-on tackle, either low or high, whereas the second player performs a front-on high tackle. If a third player is involved in a tackle, he or she makes contact with the player from the side and also above the waist.
Hit-up forwards were found to predominately stride to tackle an opponent, whereas the adjustables and outside backs were more likely to sprint on average 10-20 m into their tackles. When considering all playing positions, the most frequent activity immediately before tackling was striding, followed by sprinting, forward jogging, and finally lateral movement. These findings have implications for coaching and training on the use of a variety of locomotor activities when performing tackling drills. Tackling drills for hit-up forwards should commence from lower intensity locomotor activities (e.g., standing, walking, or jogging), whereas striding and sprinting activities should precede tackling activities for the adjustables and outside backs positional groups. There is also need to emphasize training acceleration to change velocity from a standing start to allow large momentum into tackles. It would also be reasonable to speculate that fatigue may lead to poor tackling technique and thus injury; therefore, coaching tackling drills while fatigued would be a useful training approach.
In conclusion, this study investigated the nature of and circumstances relating to the types of tackles completed by various playing positions in professional rugby league competition. The results of this study demonstrate that the majority of tackles performed by players involve collision from a front-on position and above the waist. Furthermore, the most frequent activity immediately before tackling is striding, followed by sprinting. The present data can be used to develop positional training programs that mimic the tackling protocols that elite rugby league players are likely to encounter in competition.
Tackling is one the most demanding aspects of rugby league; however, the activities before tackling and patterns of tackling according to playing position have received little or no research. This study provides some insight into the tackling demands of rugby league competition.
The greater volume of tackles in hit-up forwards highlights the need to develop contact conditioning in this playing group. The different contact demands of different positions, such as more 2 and 3-on-1 tackles in hit-up forwards, highlights the high maximal strength demands of this positional group and also the need for players to coordinate effectively together in defense. The greater volume of 1-on-1 tackles performed by outside backs demonstrates the need for overall strength to overcome attacking players in a 1-on-1 situation. The different strength training requirements and the subtle differences in activities preceding tackles in different positional groups suggest that position-specific training is required to effectively prepare players for the tackling demands of rugby league. This will also minimize injury because of correct technique and development of tackle-specific strength.
The activities preceding tackles have implications for the development of tackling drills according to the movement activity and intensity level based on playing position. Hit-up forwards were involved in a greater percentage of low-intensity activities, which may be because of their close proximity to the play-the-ball area, which emphasizes the need for acceleration work to build momentum in tackles. Outside backs had a higher percentage of high-intensity activities, such as striding and sprinting preceding tackles. The development of tackling ability with strength and wrestling components should be an integral part of rugby league training based on playing position. The ability of players to perform tackles at various movement intensities and the development of those movement activities associated should also be considered when developing training drills. With greater knowledge of the way playing positions tackle in match play coaches should be able to equip players with a physical development to effectively and safely carry out tackles under fatigue and without injury.
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Keywords:© 2011 National Strength and Conditioning Association
contact; time motion analysis; wrestling; conditioning; collision