Introduction
Rugby league is a collision sport played in several countries worldwide. The game is physically demanding, requiring players to participate in multiple physical collisions and tackles, as well as short duration, high-intensity sprinting efforts (12,21). Players are required to have well-developed physical fitness (e.g., speed, agility, strength, and power), and skill levels to tolerate the physiological demands and perform the wide range of offensive and defensive skills required of competition (17). In particular, the ability to recognize patterns of play and execute effective decisions under pressure and fatigue is an attribute of successful players.
Several investigators have assessed the agility of rugby league players using a wide range of performance tests, including the ‘L’ run, 505 test, modified 505 test, and Illinois agility run (7-15,17,19,20,25). However, a limitation of these tests is that they are all simple change of direction speed tests that rely on preplanned movements. Meir et al. (25) investigated the agility of professional rugby league players using the ‘L’ run, and found no significant differences among playing positions. Similarly, Gabbett (16) found no significant differences among hit-up forwards, adjustables, and outside backs for performance on the 505 test in elite female rugby league players. Collectively, these studies question the utility of preplanned change of direction speed tests for discriminating playing positions in rugby league. Furthermore, a limitation of these studies is that while some of the tests may reflect the general movement patterns of rugby league, the validity of the tests to discriminate between higher and lesser skilled players has not been determined. If a test cannot discriminate between higher and lower performers within a sport, its utility in detecting training-induced changes or making player selections is questionable.
Although most practitioners would classify agility as any movement involving rapid change(s) of direction, Sheppard and Young (27) have proposed that agility be defined as “a rapid, whole-body, change of direction or speed in response to a sport-specific stimulus.” While the majority of agility research has been devoted to preplanned change of direction speed tests, investigators have recently begun to study the perceptual components of agility (6,18,28). In this respect, the ability of team sport athletes to “read and react” to a game-specific stimulus has been tested. Sheppard et al. (28) demonstrated that a test of reactive agility was able to successfully discriminate higher and lesser skilled Australian football players, where preplanned change of direction speed tests did not. Gabbett et al. (18) and Farrow et al. (6) reported similar results for softball and netball players, respectively. Furthermore, while a significant relationship (r = 0.74) has been reported between linear speed and change of direction speed performance (28), the relationship between reactive agility and preplanned change of direction speed tends to be nonsignificant and moderate in magnitude. These findings may reflect the fact that effective agility performance is limited by both physical (e.g., linear speed, strength, change of direction speed) and perceptual/decision-making (e.g., visual scanning, anticipation, pattern recognition, situational knowledge) factors (31). Given the important contribution reactive agility tests have made to other team sports, it is likely that a test of reactive agility could significantly advance the understanding of agility in rugby league.
While investigators have studied speed and change of direction speed in rugby league players, no study has investigated the reactive agility of these athletes. In addition, the relationship among speed, change of direction speed, and reactive agility within the specific context of rugby league has not been determined. With this in mind, the purpose of this study was to (i) investigate a wide range of speed, change of direction speed, and reactive agility tests commonly used by rugby league coaches, to determine which, if any tests discriminated higher and lesser skilled players, (ii) determine the test-retest reliability of these tests, and (iii) investigate the relationship among speed, change of direction speed, and reactive agility in rugby league players.
Methods
Experimental Approach to the Problem
The present study used a cross-sectional experimental design to compare the speed, change of direction speed, and reactive agility of first grade and second grade rugby league players. In addition, Pearson product moment correlation coefficients were used to determine the relationship among speed, change of direction speed, and reactive agility. It was hypothesized that reactive agility performances, which relied on the ability of players to “read and react” to a game-specific stimulus, would discriminate higher and lesser skilled players. In contrast, it was hypothesized that no significant differences would be detected between first and second grade players for change of direction speed.
Subjects
Forty-two rugby league players (mean ± SD age, 23.6 ± 5.3 yr) participated in this study. All subjects were players from the same rugby league club. The club was the reigning premier in the Gold Coast Rugby League (Queensland, Australia) competition. Players had undergone a 4-month preseason conditioning program, and were in peak physical condition at the time of testing. All subjects received a clear explanation of the study, including the risks and benefits of participation, and written consent was obtained.
Players completed tests of speed (5 m, 10 m, and 20 m sprint), change of direction speed (‘L’ run, 505 test, and modified 505 test), and reactive agility on 2 occasions, 2 days apart, to determine test-retest reliability. The validity of the tests to discriminate higher and lesser skilled competitors was evaluated by testing first grade (N = 12) and second grade (N = 30) players. Players were instructed to consume their normal pretraining diet prior to the first testing session, and then replicate this diet prior to the second testing session.
Speed
The running speed of players was evaluated with a 5 m, 10 m, and 20 m sprint effort using dual beam electronic timing gates (Swift Performance Equipment, New South Wales, Australia) (5). The timing gates were positioned 5 m, 10 m, and 20 m from a pre-determined starting point. Players were instructed to run as quickly as possible along the 20 m distance from a standing start. Speed was measured to the nearest 0.01 s, with the fastest score from three trials used as the speed score.
Change of Direction Speed
The change of direction speed of players was evaluated using an ‘L’ run (29), 505 test (4), and modified 505 test.
‘L’ Run
For the ‘L’ run, 3 cones were placed 5 m apart in the shape of an ‘L’ (Figure 1) (29). Players were instructed to run as quickly as possible along the ‘L’ run. Times were measured to the nearest 0.01s with the fastest value obtained from 3 trials used as the ‘L’ run score.
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Figure 1: Schematic illustration of the ‘L’ run (
29).
505 Test
For the 505 test, 2 timing gates were placed 5 m from a designated turning point. The players assumed a starting position 10 m from the timing gates (and therefore 15 m from the turning point). Players were instructed to accelerate as quickly as possible through the timing gates, pivot on the 15 m line, and return as quickly as possible through the timing gates (Figure 2) (4). Times were measured to the nearest 0.01 s with the fastest value obtained from three trials used as the 505 test score.
Figure 2: Schematic illustration of the 505 test (
4).
Modified 505 Test
For the modified 505 test, two timing gates were placed 5 m from a designated turning point. However, unlike the traditional 505 test (where players assume a starting position 10 m from the timing gates and therefore 15 m from the turning point), players started 5 m from the timing gates. Players were instructed to accelerate as quickly as possible along the 5 m distance, pivot on the 5 m line, and return as quickly as possible through the timing gates. Times were measured to the nearest 0.01 s with the fastest value obtained from 3 trials used as the modified 505 test score.
Reactive Agility
The reactive agility test has been described in detail elsewhere (28). In brief, the athlete began on the marked line, as illustrated in Figure 3. Timing gates were placed 5 meters to the left and right and 2 meters forward of the start line. Therefore, the timing gates were placed 10 meters from each other.
Figure 3: Schematic illustration of the reactive agility test (
28).
The tester (investigator) stood opposite and facing the participants. The tester stood behind a set of timing lights. Each test trial involved the tester initiating movement, and thereby beginning the timing. The athlete reacted to the movements of the tester by moving forward, then to the left or right in response to, and in the same direction as, the left or right movement of the tester. The timing stopped when the athlete triggered the timing beam on either side.
The tester displayed one of four possible scenarios for the athlete to react to; however the athletes did not explicitly know this. The four possible scenarios all involved steps of approximately one-half meter, and were presented in a random order that was different for each athlete:
- Step forward with right foot and change direction to the left.
- Step forward with the left foot and change direction to the right.
- Step forward with the right foot, then left, and change direction to the right.
- Step forward with the left foot, then right, and change direction to the left.
There was an equal number of each scenario presented for each participant. The test protocol involved randomized presentation of 4 different cues, for a total of 8 trials. These cues created varying demands on the participants (as in a game setting), resulting in intertrial variability. For this reason, the recorded score used was the mean of all trials (8), which was an average of all trials to the left (4) and to the right (4).
The participants sprinted forward prior to any change of direction, in reaction to the forward movement of the tester. The participant was instructed to recognize the cues as soon as possible (essentially while moving forward), and react by changing direction and sprinting through the gates on the left or right in response. The participants were instructed to emphasize accuracy (decision-making accuracy) and speed of movement. A high speed video camera (HSC-200 PM, Peak Performance Technologies, Inc., Centennial, Colo.) interfaced with a video recorder (Panasonic AG-5700, Belrose, Australia) was positioned 5 m behind the subject in order to record the subject's change of movement direction relative to the tester. Video was sampled at 200 Hz so that the number of frames between the tester's and player's movement initiation enabled the player's decision-making time to be recorded to within ± 5 ms for each trial.
Statistical Analyses
The test-retest reliability of the speed, change of direction speed, and reactive agility tests were evaluated using intraclass correlation coefficients (ICC) (26) and the typical error of measurement (TE) (23). Differences in performances between first grade and second grade players were compared using an independent t-test and Cohen's effect size (ES) statistic (3). Effect sizes of 0.1, 0.5, and 0.8 were considered small, moderate, and large, respectively (1). The Pearson product moment correlation coefficient was used to determine the relationship among speed, change of direction speed, and reactive agility performances. The level of significance was set at P ≤ 0.05 and all data are reported as mean ± SD.
Results
Test-Retest Reliability
The Test and Re-Test measurements of speed, change of direction speed, and reactive agility proved to be reliable. The ICC and TE for 5 m, 10 m, and 20 m speed were 0.84 to 0.96, and 1.3% to 3.2%, respectively. All change of direction speed tests were reliable with the 505 test having the best reliability (r = 0.90, TE = 1.9%). The modified 505 test (r = 0.92, TE = 2.5%) and ‘L’ run (r = 0.95, TE = 2.8%) had similar reliability. Movement time, decision time, and response accuracy on the reactive agility test were also highly reproducible (Table 1).
Table 1: Test-retest reliability of speed, change of direction speed, and reactive agility tests.
Differences Between First Grade and Second Grade Players
First grade players had faster (P < 0.05) 5 m (ES = 0.68), 10 m (ES = 0.85), and 20 m (ES = 0.75) sprint times than second grade players (Table 2). In addition, first grade players had faster movement (P < 0.05, ES = 0.73) and decision (ES = 0.54) times on the reactive agility test than second grade players. No significant differences (P > 0.05, ES = 0.28 to 0.32) were detected between first and second grade players for change of direction speed (i.e. 505 test, modified 505 test, and ‘L’ run).
Table 2: Speed, change of direction speed, and reactive agility results for first grade and second grade rugby league players.
Relationship Among Speed, Change of Direction Speed, and Reactive Agility
The 5 m, 10 m, and 20 m sprint times were significantly correlated (P < 0.05) with performances on the 505 test, ‘L’ run, and modified 505 test. Furthermore, movement times on the reactive agility test were significantly related (P < 0.05) to 10m and 20m sprint times, and change of direction speed. Decision time on the reactive agility test was significantly related (r = 0.58, P < 0.05) to response accuracy. An inverse relationship (r = −0.50, P < 0.05) existed between response accuracy and movement speed on the reactive agility test. No significant relationships (P > 0.05) were detected among measures of decision time and response accuracy during the reactive agility test and measures of linear speed and change of direction speed (Table 3).
Table 3: Relationship among speed, change of direction speed, and reactive agility in rugby league players.
Discussion
The purpose of this study was to investigate a wide range of speed, change of direction speed, and reactive agility tests commonly used by rugby league coaches to evaluate test-retest reliability, and determine which, if any, tests discriminated higher and lesser skilled players. In addition, the relationship among speed, change of direction speed, and reactive agility was also determined. The results of this study demonstrate that while the 505 test, modified 505 test, and ‘L’ run may simulate the “general” movement patterns of rugby league match-play, none of these change of direction speed tests offer a valid method of discriminating higher and lesser skilled players. However, in contrast to the results from the change of direction speed tests, movement and decision times on the reactive agility test were faster in higher skilled players, without compromising response accuracy. The finding of superior anticipatory skill in the first grade players of the present study suggests that these players had a greater ability to extract relevant information earlier in the visual display, by identifying relevant postural cues presented by the tester, and disregarding irrelevant sources of information (22). Collectively these findings demonstrate the practical utility of the reactive agility test for assessing the perceptual components of agility, while also raising questions on the validity of preplanned change of direction speed tests currently used by the majority of rugby league coaches.
A novel aspect in the present investigation of rugby league players, which has rarely been addressed in previous agility studies, was the assessment of reliability. Test-retest reliability was evaluated for all speed (5 m, 10 m, and 20 m sprint), change of direction speed (505 test, modified 505 test, and ‘L’ run), and reactive agility tests. Although reliability measures should be considered population-specific, the relatively low typical error of measurement found in this study suggest that all of the change of direction speed tests, and the reactive agility test, have low variability and therefore are equally useful for tracking training induced changes in performance.
Among a squad of rugby league players, the reactive agility test was able to distinguish four distinct classifications (Table 4). Specifically, players were classified as requiring either: (i) decision-making and change of direction speed training to further consolidate good physical and perceptual abilities, (ii) decision-making training to develop below average perceptual abilities, (iii) speed and change of direction speed training to develop below average physical attributes, or (iv) a combination of decision-making and change of direction speed training to develop below average physical and perceptual abilities.
Table 4: Interpretation and training prescription for four players with different results on the reactive agility test.
The inclusion of decision time and response accuracy information using high speed video footage provides additional insight into the anticipatory strengths and weaknesses of rugby league players. The analysis of the high speed video footage allows for a delineation of the performance components of the reactive agility test, by elucidating whether the test was limited by decision time or movement speed. Indeed, if movement time alone was used to classify reactive agility, some players would be incorrectly classified as having superior anticipatory skill (i.e., “fast thinkers”). It should also be noted that a speed-accuracy trade-off exists in the majority of players, so that reductions in decision time (i.e., faster decision-making ability) result in reductions in response accuracy.
The reactive agility test used in this study is designed as a defensive (or pursuant) test. Therefore, it is possible that some players with good attacking skills may have performed poorly on this test. An assessment of the reactive agility of players from an attacking perspective may provide additional information not provided through the use of a defensive test. It addition, it is possible that the high response accuracy (i.e. 85.5%) in this study is due to the high anticipatory skill of the tested players. However, it is also possible that the 1-on-26 cues presented by a non-playing ‘tester’ were inadequate to challenge the perceptual abilities of the ‘expert’ decision-makers within the squad (24). Consequently, the present results should be considered a starting point for further research in this area. Specifically, the development of a ‘life-like’ video-based anticipation test that encompasses game-specific scenarios (and more than one attacking player) should be a priority for future rugby league reactive agility and decision-making research.
The present study found a significant association between sprinting speed and performance on all change of direction speed tests. These findings are in conflict with previous studies (2,4,30) that have found a poor to moderate relationship between linear sprinting speed and change of direction speed. Furthermore, the relationship between the ‘L’ run (which employed 3 changes of direction) and 5 m, 10 m, and 20 m sprint times was stronger (r = 0.57-0.73) than that observed for the 505 (r = 0.52-0.58) and modified 505 (r = 0.61-0.62) tests, which both employed 1 change of direction. These findings are in direct conflict with Young et al. (30), who have suggested that the relationship between linear sprinting speed and change of direction speed weakens with greater changes of direction. Performances on all change of direction speed tests were significantly, albeit moderately associated (r = 0.40-0.58) with movement times on the reactive agility test, suggesting that reactive agility movement times are influenced by the change of direction speed of athletes. However, the low common variance (16-34%) between reactive agility movement times and change of direction speed, coupled with the lack of significant relationship among decision time, response accuracy, and change of direction speed suggest that reactive agility performances are influenced by factors in addition to, or other than (e.g., visual scanning, anticipation, pattern recognition, and situational knowledge) (31) change of direction speed.
In conclusion, this study investigated a wide range of speed, change of direction speed, and reactive agility tests commonly used by rugby league coaches, to determine which, if any tests discriminated higher and lesser skilled players, and determined the relationship among speed, change of direction speed, and reactive agility in these athletes. These findings question the validity of preplanned change of direction speed tests for discriminating higher and lesser skilled rugby league players, while also highlighting the contribution of perceptual skill to agility in these athletes.
Practical Applications
Previous studies of ‘agility’ in rugby league players have investigated the preplanned change of direction speed of these athletes (8, 25). A limitation of studies performed to date, is that a wide range of tests have been employed (e.g. Illinois agility run, 505 test, modified 505 test, and ‘L’ run) with none of these tests assessing the perceptual components of agility. Consequently, the superior ability of highly skilled players to ‘read and react’ to a game-specific stimulus has not been considered. A major concern with the current battery of change of direction speed tests used by rugby league coaches is that none of the tests employed offer a valid method of discriminating higher and lesser skilled players.
This is the first study to assess the reactive agility of rugby league players. The finding of superior movement speed, decision times, and response accuracy in first grade players in comparison to second grade players, demonstrates the practical utility of the reactive agility test for assessing the perceptual components of agility in rugby league players. However, the success of any testing battery is dependent on the ability of strength and conditioning coaches to identifyindividual performance limitations and provide game-specific programs to rectify these weaknesses. When developing reactive agility training drills for rugby league players, it is recommended that strength and conditioning coaches consider the physiological demands (e.g., work to rest ratios, physical contact), workspace of individual positional groups, and relative importance of reactive agility so that perceptual skills are trained under game-specific conditions.
Finally, while a significant relationship was observed between linear sprinting speed and change of direction speed, decision time and response accuracy were unrelated to change of direction speed, suggesting that the preplanned change of direction speed tests and the reactive agility test are assessing two distinct, but different qualities (28). Consequently, ‘agility’ programs designed to improve these qualities should employ different training strategies. Players with poor change of direction speed results require additional speed and change of direction speed training to improve their physical qualities, while players with poor reactive agility results would likely benefit from additional decision-making training to improve perceptual skill.
Note: At the time of the study, the primary author was employed by the Queensland Academy of Sport, Brisbane, Australia.
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