Applied Science of Professional Rugby League

Tim Gabbett (2011). Applied Science of Professional Rugby League PhD Thesis, School of Human Movement Studies, The University of Queensland.

       
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Author Tim Gabbett
Thesis Title Applied Science of Professional Rugby League
School, Centre or Institute School of Human Movement Studies
Institution The University of Queensland
Publication date 2011-10
Thesis type PhD Thesis
Supervisor Bruce Abernethy
David Jenkins
Total pages 574
Total colour pages 8
Total black and white pages 566
Language eng
Subjects 110602 Exercise Physiology
110603 Motor Control
110604 Sports Medicine
Abstract/Summary ABSTRACT The present thesis examined the applied science of professional rugby league, with a particular focus on (1) the applied physiology of rugby league, (2) skill acquisition in rugby league, and (3) injury incidence in rugby league. In theme one (the Applied Physiology of Rugby League), the specific physical demands of professional rugby league match-play, and the use of game-based training as a means of replicating these demands were investigated. Using both global positioning system (GPS) and ball-in-play analysis, it was revealed that the relative locomotor demands of professional rugby league match-play were similar between hit-up forwards, wide-running forwards, adjustables, and outside backs, although outside backs covered greater absolute distances than other playing positions. In addition, the high-speed running demands were greater in adjustables and outside backs, while the collision and repeated high-intensity effort demands were greater in hit-up forwards and wide-running forwards. The greatest distances covered, high-speed running distances, and frequency of collisions and repeated high-intensity effort bouts were up to 98% greater than the average physical demands. These findings suggest that conditioning programs that are based on the mean values of competition will likely result in players being underprepared for the most demanding passages of competition. The ‘ball-in-play’ analysis demonstrated that players were required to compete for prolonged periods of play, with short recovery periods during brief stoppages in play. Neither traditional conditioning, repeated high-intensity effort training, nor game-based training adequately replicated the physical demands of match-play, suggesting that improvements in conditioning practices may be necessary to adequately prepare players for National Rugby League competition. Differences in the physical demands between National Rugby League and National Youth Competition matches, and junior and senior small-sided games were observed, as evidenced by differences in match activity cycles and high-intensity running demands. The ball was in play longer in National Rugby League matches (~55 min) than National Youth Competition matches (~50 min), and National Rugby League matches had longer average activity cycles (81.2 ± 16.1 s vs. 72.0 ± 14.7 s), longer maximal activity cycles (318.3 ± 65.4 s vs. 288.9 ± 57.5 s), a smaller proportion of short duration (<45 s) activity cycles, and a greater proportion of longer duration (>91-600 s) activity cycles. In addition, senior players covered greater total distances, and completed greater amounts of high-speed running than junior players in small-sided games. Given the salary cap constraints in the National Rugby League competition, teams face pressures to retain older, more experienced players within their playing roster. Due to these pressures, talented, younger players are often ‘fast-tracked’ to the National Rugby League. The differences in physical demands between National Rugby League and National Youth Competition matches, and junior and senior small-sided games, suggest that physical preparation should differ between younger and older players. Perhaps more importantly, the present findings suggest that the training demands of National Youth Competition players should be increased in preparation for National Rugby League matches. In theme two (Skill Acquisition in Rugby League), dual-task techniques were used to assess the attentional demands of selected rugby league skills, as a tool to both measure and ultimately facilitate skill learning. These methods were also used to determine the relationship between off-field measures of skill and competition performances. Differences were found in the dual-task draw and pass proficiency of higher-skilled and lesser-skilled rugby league players, despite a lack of significant differences in primary task performance. These findings demonstrate the advantage of dual-task performance assessments over single-task measures in predicting the capability of different players to compete successfully at a higher level where concurrent demands are high. Based on this information, coaches may use the dual-task draw and pass assessment to provide insight into the level of practice complexity required by individual players. Dual-task training appeared to have some benefits for skill learning, resulting in better acquisition and retention of skill compared to conventional single-task training. Indeed, the mean improvement in dual-task draw and pass proficiency in a dual-task training group (10.0%) was found to be greater than that in a single-task training group (2.3%), offering a moderate effect size (d = 0.57). However, no differences were found in transfer test performance (a small-sided game which provided regular draw and pass opportunities) between players trained under single-task and dual-task conditions. While dual-task training appears to offer advantages over single-task training as a skill learning stimulus to improve time-sharing and dual-task draw and pass performance, further studies are required to confirm the transfer of this advantage to match-like situations. The dual-task draw and pass proficiency of rugby league players (assessed off-field) was related meaningfully to player performance in competition; higher dual-task performance assessed off-field was associated with more successful competition draw and pass attempts. In addition, draw and pass proficiency declined with increases in task complexity. These findings provide evidence of the greater attentional demands of more complex drawing and passing scenarios in professional rugby league. From a practical perspective, these findings also provide evidence of the practical utility of off-field dual-task testing in supplying information predictive of skills performance in competition. Expert-novice differences were found in the dual-task anticipatory skill of rugby league players in response to a “life-like” game-specific video-based test. High-skilled rugby league players had greater response accuracy and decision times than intermediate- and low-skilled players. Furthermore, secondary task performance (verbal reaction times and accuracy in response to a tone recognition task) was poorer in the low-skilled players, demonstrating the increased attentional demands that novice rugby league players experience while performing game-specific decision-making tasks. The anticipation test has several potential practical applications. Firstly, it is likely that it could be used to complement existing measures of playing ability for selecting individuals for higher level representation. Secondly, within National Rugby League high performance programs, the test may be used diagnostically to identify individuals who have a specific need for training in anticipatory skills. Finally, additional video clips of scenarios not used in the anticipation test, could be used to train anticipatory skills, and complement on-field training performed in rugby league training sessions. In theme three (Injury Incidence in Rugby League), the relationship between physical and skill qualities, training loads and injury risk were investigated. In addition, an injury prediction model to prevent non-contact, soft-tissue injuries was developed and implemented. Significant relationships were found between training load and injury with greater training loads being associated with higher injury rates. High strength and power training loads were associated with increases in field injury rates, while greater than average volumes of high-speed running increased the risk of lower-body soft-tissue injury. However, some training factors protected against lower-body soft-tissue injury, with greater amounts of aerobic activity (i.e., low-speed running) being associated with a lower risk of soft-tissue injury. In addition, players with poor repeated-sprint ability and prolonged high-intensity intermittent running ability were at greater risk of sustaining a contact injury. These findings, taken with the physical demands of professional rugby league match-play (i.e. long ball in play periods, and regular performance of repeated high-intensity effort bouts), and the protective effect that well-developed aerobic qualities have against fatigue-induced reductions in skill, demonstrate the importance of high-intensity aerobic training for performance enhancement and injury prevention in professional rugby league players. Based on the relationship between training load and injury, an injury prediction model was developed and implemented. Training load ‘thresholds’ were developed for players on an individual basis. The injury prediction model was found to have acceptable specificity (98.8%) and sensitivity (87.1%). When players exceeded the training load thresholds, they were injured 70 times more often, whereas when training loads were below the injury threshold, players were injured 1/10 as often. These findings provide information on the training dose-response relationship and a scientific method of monitoring and regulating training load in elite rugby league players. Summary The findings of the conducted experiments demonstrate that: 1. The high-speed running demands of professional rugby league match-play are greater in adjustables and outside backs, while the collision and repeated high-intensity effort demands are greater in hit-up forwards and wide-running forwards. 2. Neither traditional conditioning, repeated high-intensity effort training, nor game-based training, adequately replicate the physical demands of match-play, suggesting that improvements in conditioning practices may be necessary to properly prepare players for National Rugby League competition. 3. The physical demands of National Rugby League matches are significantly greater than National Youth Competition matches. The ball was in play longer in National Rugby League matches (~55 min) than National Youth Competition matches (~50 min), and National Rugby League matches had longer average activity cycles (81.2 s vs. 72.0 s), longer maximal activity cycles (318.3 s vs. 288.9 s), a smaller proportion of short duration (<45 s) activity cycles and a greater proportion of longer duration (>91-600 s) activity cycles. 4. Selected physical (e.g. acceleration, maximum velocity, lean body mass, lower body muscular power, and maximal aerobic power) and skill (e.g. tackling proficiency, dual-task draw and pass proficiency) qualities discriminated high-skilled and lesser-skilled rugby league players. In addition, high-skilled players were older and more experienced than lesser-skilled players. 5. Selected physical and skill qualities were related to game performance. Better repeated-sprint ability, and prolonged high-intensity running ability were associated with greater minutes played, while dual-task draw and pass proficiency was significantly associated with the number of try assists and line break assists. 6. Greater lower body muscular power, acceleration, change of direction speed, and lean body mass, along with greater age and playing experience were associated with better tackling proficiency. In addition, greater aerobic fitness was protective against fatigue-induced reductions in tackling proficiency. 7. Differences were observed between high-skilled and lesser-skilled players on a dual-task draw and pass assessment. While no differences were detected in primary task performance between groups, the performance of the high-skilled players was more resistant to skill decrement under dual-task conditions. 8. Eight weeks of dual-task training appeared to have some benefits for skill learning, resulting in better acquisition and retention of this important skill. The mean improvement in dual-task draw and pass proficiency in the dual-task training group (10.0%) was greater than the single-task training group (2.3%), although no differences were found in transfer test performance between players trained under single-task and dual-task conditions. 9. The dual-task draw and pass proficiency of rugby league players (assessed off-field) was related to competition performances; higher dual-task performance was associated with more successful competition draw and pass attempts. 10. High-skilled rugby league players had greater response accuracy and decision times than intermediate- and low-skilled players on a “life-like” game-specific video-based anticipation test. Furthermore, secondary task performance (verbal reaction times and accuracy in response to a tone recognition task) was poorer in the low-skilled players, demonstrating the increased attentional demands of performing game-specific decision-making tasks in novice rugby league players. 11. A significant relationship was found between training loads and injury; greater training loads were associated with higher injury rates. High strength and power training loads were associated with increases in field injury rates, while greater than average volumes of high-speed running increased the risk of lower-body soft-tissue injury. 12. An injury prediction model was developed and implemented to prevent non-contact, soft-tissue injuries. The injury prediction model was found to have acceptable specificity (98.8%) and sensitivity (87.1%). When players exceeded the training load thresholds, they were injured 70 times as often, whereas when training loads were below the injury threshold, players were injured 1/10 as often. These findings suggest that systematically applying sport science to rugby league offers a promising means of developing effective and evidence-based approaches to physical preparation, skill acquisition, and injury prevention.
Keyword Skill Acquisition
Physical Demands
Injury
Performance
National Rugby League
Collision Sport
Global Positioning System
Training Load
Dual-Task
Game-Based Training
Additional Notes Colour Pages: 229, 272, 313-315, 557, 573, 574 Landscape Pages: 51, 97, 98, 140, 141, 148, 151-157, 173, 178, 186, 204, 205, 229, 237, 240, 260, 283, 284, 299, 313-315, 323-327, 350-352, 367, 378, 379, 387, 398, 436, 452, 461, 463-466, 476-478, 492-495, 497, 498

 
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Created: Thu, 14 Jun 2012, 16:16:32 EST by Tim Gabbett on behalf of Library - Information Access Service