Rugby league (RL) and rugby union (RU) have similarities in game duration, field size, and goal posts and also distinct differences in rules and scoring. An RU team consists of 15 players, whereas RL has 2 less forward positions with 13 players. One of the main differences between RL and RU lies in what happens in the tackle situation. When a player is tackled in union, the ball is recycled by a ruck or by a maul, with no limit to the number of phases. A tackled player in league stops play, with the team in possession able to recycle the ball up to 6 times before the ball is handed over to the opposition. Another significant difference is what happens when the ball goes into touch. In union, play is restarted with a lineout, whereas in league play, it is restarted with a scrum, retention, or changeover in possession. Similarities will always be drawn between these 2 sports, because of the resemblance of the games player positions, field dimensions and inclusions of tackling, and scrums.
Time-motion analysis from RL and RU has shown that the accumulated distances sprinted by players during most games are relatively small compared with the total distances covered by players in a match (6–8,10,17,18). However, it has been suggested that ‘repeated-sprint ability’ of players may be critical to the outcome of a match (14,21). Furthermore, the occurrence of repeated high-intensity exercise (RHIE) bouts has been shown to arise frequently in professional rugby codes (1–3,10,13).
The nature and frequency of RHIE in professional RL and RU match play have been recently described (2,10). An RHIE bout was defined as ≥3 sprints, tackles, scrum, ruck, or maul activities within 21 seconds during the same passage of play (modified from 22). It was found that the front row (15 ± 3) and back row forwards (17 ± 4) in RU had the highest frequency of RHIE bouts in match play, compared with the RL forwards (12 ± 3). Similarly, RU backs completed a greater frequency of RHIE bouts than RL backs (7 ± 3 and 16 ± 2 for the RU outside and inside backs, respectively, and 6 ± 3 and 5 ± 1 for the RL adjustables and outside backs, respectively). Inclusion of scrums, rucks, and mauls in RU accounted largely for the observed differences between the codes. The majority of sprints in RL were over a distance of 6–10 m, whereas the majority of RU players sprinted between 11 and 20 m. Both outside backs in RL and RU had the highest frequency of sprints >20 m.
High-intensity, intermittent team sports typically use tests of speed (20,23), repeated-sprint ability (8,20), and high-intensity intermittent running ability (5,15,16) to assess physical performance and adaptations to training. However, repeated-sprint ability tests alone may underestimate the RHIE demands of the rugby codes (13) and therefore the preparedness of players to perform the RHIE (sprinting, tackling, scrummaging, and wrestling) bouts required in these sports. Indeed, recent evidence has shown that repeated effort exercise (involving sprinting and tackling with minimal recovery) is associated with significantly greater heart rate, perceived exertion, and fatigue than exercise involving repeated-sprinting (with minimal recovery) in isolation (13). Given the frequency of RHIE bouts during competition relative to repeated-sprint bouts (10) and that these bouts may occur at critical periods of a game (2), a test that replicates these demanding passages of play, and assesses the ability of players to perform these RHIE activities, would provide important information on the individual RHIE strengths and weaknesses of players. It is likely that such a test would also provide important information to supplement that obtained from more traditional high-intensity intermittent running (e.g., yo-yo intermittent recovery) (5,15,16) and speed (20,23) tests. With this in mind, the purpose of this study was to examine the reliability and sensitivity of 3 RHIE tests for professional RL and RU players. The exercise tests were designed to capture the intensities and durations of RHIE bouts found for professional RL and RU players. Sensitivity was assessed through changes in RHIE test performance over a 10-week period of preseason training in elite RU and RL players. Training-induced performance changes in the RHIE tests were also compared with changes in the yo-yo intermittent recovery test (YYIRT) and 20-m sprint times.
Experimental Approach to the Problem
This project was completed in several phases. First, the RHIE demands of Super 14 and National Rugby League competition were investigated using time-motion analysis (2,3). Based on the results of the time-motion analysis, ecologically valid and game-specific RHIE tests were developed to reflect the most extreme demands of competition in terms of number and duration of sprints, tackles and mauls, and recovery between sprints. The tests were designed to measure the player's ability to perform these RHIE bouts, using total sprint time and performance decrement as dependent variables. Second, the test-retest reliability of the test was determined by having each player perform the test twice within 7 days. Reliability was assessed using intraclass correlation coefficients (ICCs) and coefficients of variation. Third, the sensitivity of the test to detect training-induced changes in RHIE ability was determined by assessing the performance of players before, and after a 10-week preseason conditioning program. Finally, the relationship between the new RHIE test and tests of speed (20-m sprint) and high-intensity intermittent running ability (yo-yo intermittent recovery test) was determined using Pearson product moment correlation coefficients.
Reliability was tested with 36 professional RU players, separated into 3 equal groups based on playing position: backs (age: 24 ± 4 years, height: 180 ± 4 cm, body mass: 93 ± 10 kg), RL forwards (age: 24 ± 4 years, height: 186 ± 8 cm, body mass: 103 ± 10 kg), and RU forwards (age: 24 ± 3 years, height: 190 ± 8 cm, body mass: 109 ± 7 kg). Sensitivity of the test to detect training-induced changes in RHIE ability was determined in 12 professional RL backs (age: 24 ± 4 years), 12 professional RL forwards (age: 22 ± 2 years), and 12 semiprofessional RU forwards (age: 24 ± 3 years). The research was approved by an ethics committee of The University of Queensland and all subjects involved in the study provided informed consent before data collection.
The results of the time-motion analysis have been presented previously (2,3). In brief, the maximum number of sprints and tackles within an RHIE bout was 6, whereas up to 10 scrummaging activities were included in RU RHIE bouts. The majority of sprints were over a distance of ≤20 m, whereas 2–4 sprints occurred in a maximal RHIE bout. The longest RHIE bout covered a total distance of 136 m and included 26 separate activities. Rugby league forwards had double the involvement in tackling than backs, whereas RU backs had little involvement in scrummaging. Based on the results of the time-motion analysis, the developed tests consisted of repeated-sprinting, interspersed with tackling, and scrummaging activities.
The players from each of the 3 positional groups (i.e., RL and RU backs, RL forwards, and RU forwards) completed the same positional RHIE test twice within 7 days; at least 48 hours separated each test. All players were assigned a test based on their own playing position of forward or back. The players were familiarized with the test protocol 1 week before the first test. They avoided strenuous activity the day before the test and all testing was undertaken before a scheduled training session. In addition, the players were asked to replicate their activities and nutritional intake in the 2 days before each test.
Each test was preceded by a 10-minute standardized warm-up that included static and dynamic stretching, a gradual increase in running intensity, and the involvement of upper body movements replicating ground contact and tackling. After the warm-up, the players completed their assigned test. Each test was recorded using timing gates (Smartspeed, Fusion Sport, Queensland, Australia). The players were verbally encouraged throughout the test to minimize the possibility of pacing.
RHIE Backs Test
Each player started with his toes behind a marker, which was 0.5 m behind the light beam of the first timing gate (Figure 1). He then completed three 20-m sprints through the timing gates before decelerating and jogging to the start; sprints were performed on a 20-second turnaround, with approximately 16–17 second active recovery. The players were instructed to sprint with maximal effort. After completing 3 sprints (and after a 60-second recovery), the player moved to the side of the running lane and completed 2 tackles; he sprinted 10 m to tackle a bag (Hart Sport Senior Tackle Bag; 1,510 mm × 450 mm, 11 kg), driving it at least 2 m. He then ran backward to the start and 20 seconds later completed a second tackle. A 20-second recovery followed the tackle shuttle; the player then repeated the 3 × 20-m sprint protocol and tackle drill. In total, the player completed the sprint and tackle drills 3 times. Sprint times were recorded for analysis; individual sprint times and the sum of sprint times were compared. Decrement in sprint times was analyzed over the 3 sets of sprints performed.
RHIE RL Forward Test
The RL (forwards) test was similar to the test for the backs, except that players completed 5 tackles (rather than 2) in each ‘circuit.’ The distances players sprinted was the same as for the previously described test but because 5 tackles were completed (vs. 2), the total distance covered by the players in this test was greater (100 vs. 40 m). Figure 1 provides the details of the test.
RHIE RU Forward Test
The test for the RU forwards differed to the 2 tests described above, in the number of sprints completed, a reduced number of tackles, and the inclusion of scrummaging (Figure 2). Each player first completed three 20-m sprints, running through timing gates, before decelerating and jogging to the start. Again, each was instructed to sprint with maximal effort. As with the other tests, each sprint was performed on a 20-second cycle, leaving approximate 16- to 17-second recovery between sprint efforts. After the third sprint in each set and after a 60-second rest, the player moved to the side of the running lane to complete a ‘scrum sled shuttle.’ This involved pushing a weighted (80 kg) scrum sled (Rhino Rugby one man machine, Somerset, United Kingdom) 5 m in 1 direction and 5 m back to the start. The player completed this 4 times, with a 10-second rest between bouts. On completion of the scrum sled shuttle, the player was given 20 seconds to return to the sprint lane. He then repeated the sprint shuttles (3 × 20 m) before moving to the tackle drill. After a 60-second rest, he sprinted 10 m and tackled a tackle bag (Hart Sport Senior Tackle Bag; 1510 mm × 450 mm, 11 kg), driving it at least 2 m. On completion of the tackle, he ran backward to the start line and repeated the tackle drill on 4 occasions; 20 seconds separated the start of each sprint to tackle. A final set of 3 sprints then concluded the test. Times were recorded for each sprint repetition (total of 9). Again, sprint times were recorded for analysis; individual sprint times, and the sum of sprint times were compared. Decrement in sprint times was analyzed over the 3 sets of sprints performed.
The players undertook the RHIE test and the YYIRT (level 2) in the second (T1), sixth (T2), and tenth (T3) week of preseason training. Testing preceded scheduled training sessions; the players randomly completed either the YYIRT or RHIE test on consecutive days. All the players involved in the study followed a generic preseason training program monitored closely by the respective coaching staff. Training sessions included low- to high-intensity running through games, skills, sprint development, specific conditioning sessions, resistance training and various other activities such as boxing, agility work, and jumps.
Yo-Yo Intermittent Recovery Test
The YYIRT evaluates an individual's ability to perform repeated high-intensity running (5,15). The test consisted of 2 repeated 20-m runs back and forth between the starting, turning and finishing lines at progressively increasing speeds, controlled by audio cues from a media player. Between each running bout, the participants had 10 seconds of active recovery that involved jogging 2 × 5 m. When a participant twice failed to reach the finishing line before the next audio cue, the distance covered was recorded as the final test result. For this investigation, the players performed the test at level 2.
The fastest 20-m sprint time from the first 3 sprint sets of the RHIE test was recorded as the measure of speed. The players sprinted from a stationary start and split times at 10- and 20-m time were recorded to the nearest 0.01 seconds using 4 sets of electronic timing lights (Fusion Sport Pty Ltd., Brisbane, Australia).
Total sprint times and sprint performance decrements were used as dependent variables (Table 1). Total sprint time was the sum of all 3 sets of sprints (nine 20-m sprints in total). Decrement in sprint performance was calculated as the difference in time taken (seconds) to complete the third set of sprints (sprints 7–9) compared with the total time taken to complete the first set of 3 sprints (sprints 1–3). This is consistent with the approach of Wragg et al. (24). Reliability was assessed using ICCs and coefficients of variation (CVs) for the total sprint time and sprint performance decrements (11). The strength of the ICC was determined using the following criteria: 0.90—high, between 0.80 and 0.90—moderate, and <0.80—low (25). Repeated-measures analysis of variance was used to assess changes in outcome measures across the 3 test periods; Tukey's post hoc analysis was used to locate differences between T1, T2, and T3 values. Pearson's correlation coefficients were used to assess the association between test results (from the RHIE tests, the YYIRT, and 20-m sprint times) at T1, T2, and T3. Effect size (ES) statistics were also calculated to assess the magnitude of changes in test performance over time. All data are presented as mean ± SD, and significance was set at p ≤0.05.
RHIE Back Test
The CV for the 2 trials for the backs was 0.001–0.032 seconds (0.1–3.2%), and the ICC was 0.82 (p < 0.05). The CV for sprint decrement across the 2 trials for the backs was 0.04–0.50 seconds (4.2–49.5%), and the ICC was 0.78 (p < 0.05).
RHIE RL Forward Test
The CV for the 2 trials for the RL forwards was 0.001–0.049 seconds (0.1–4.9%), and the ICC was 0.97 (p < 0.05). The CV for sprint decrement across the 2 trials for the RL forwards was 0.01–0.48 seconds (1.4–48.2%), and the ICC was 0.86 (p < 0.05).
RHIE RU Forward Test
The CV for the 2 trials for the RU forwards was 0.001–0.051 seconds (0.1–5.1%), and the ICC was 0.94 (p < 0.05). The CV for sprint decrement across the 2 trials for the RU forwards was 0.01–0.36 seconds (0.6–35.8%), and the ICC was 0.88 (p < 0.05).
Total Sprint Time
Total sprint times for the RHIE backs decreased over the 3 tests by 0.39 seconds (T1 to T2) (p > 0.05) and 0.15 seconds (T2 to T3) (p > 0.05); the change in total sprint times between T1 and T3 was 0.54 seconds (p > 0.05; ES = 0.75). Times for the RHIERL forwards tended to increase between T1 and T2 (p > 0.05) and decrease between T2 to T3 (p > 0.05); the reduction in total sprint time between T1 and T3 was 0.53 seconds (p > 0.05; ES = 0.85). Total sprint times for RHIERU forwards improved over the 3 tests by 1.57 seconds (T1 to T2) (p < 0.02) and 0.52 seconds (T2 to T3) (p < 0.05); the change in the total sprint times between T1 and T3 was 2.09 seconds (p < 0.01; ES = 1.34) (Figure 3).
Performance decrements in the RHIEbacks test over T1, T2, and T3 were 0.57 ± 0.39, 0.39 ± 0.19, and 0.45 ± 0.19 seconds, respectively. There was no significant change from T1 to T3 (0.13 seconds; p > 0.05; ES = 0.39). Performance decrements in the RHIERL forwards test over T1, T2, and T3 were 0.31 ± 0.19, 0.58 ± 1.24, and 0.23 ± 0.13 seconds, respectively. There was no significant change between T1 and T3 (0.09 ± 0.19 seconds; p > 0.05; ES = 0.49). Performance decrements in the RHIERU forwards test at T1, T2, and T3 were 1.50 ± 1.52, 0.47 ± 0.25, and 0.28 ± 0.34 seconds, respectively; the change in performance decrement of 1.16 ± 1.47 seconds, from T1 to T3 was statistically significant (p < 0.05; ES = 1.11).
Best Twenty-Meter Sprint
Changes in 20-m sprint times for combined backs from T1 to T3 were not statistically significant (p > 0.05; ES = 0.46). The CV over the 3 tests for 20-m sprint times ranged from 0.002 to 0.016 (CV%: 0.21–1.61%). Rugby league forwards improved in the 20-m sprint time between T1 and T3 by 0.04 seconds (p < 0.05; ES = 0.67). The CV for 20-m sprint times ranged from 0.001 to 0.021 (CV%: 0.10–2.09%). Between T1 and T3, the RU forwards had a significant 9.3% improvement in sprint times (p < 0.05; ES = 1.05). The CV ranged from 0.003 to 0.049 (CV%: 0.32–4.92%) (Figure 4).
Yo-Yo Intermittent Recovery Test
The YYIRT performance for the backs ranged from level 15.8 (1,080 m) to 19.8 (2,360 m). The mean levels for the YYIRT at T1, T2, and T3 were 17.8 ± 0.9, 18.2 ± 0.6, and 18.8 ± 0.6, respectively (p < 0.05; T1 to T3, ES = 1.31) (Figure 5). The CV for the YYIRT test ranged from 0.021 to 0.238 (CV%: 2.1–23.9%). There was a significant change in YYIRT performance between T1 and T3 (2,678 ± 125 m; p < 0.05; ES = 1.42) for the RL forwards. The CV for YYIRT performance ranged from 0.019 to 0.137 (CV%: 1.9–13.7%). YYIRT performance for the RU forwards ranged from level 14.4 (600 m) to 19.2 (2,120 m). The mean values for the YYIRT at T1, T2, and T3 were 16.4 ± 1.1, 16.8 ± 1.1, and 17.3 ± 1.1, respectively (T1 to T3, ES = 0.82). The CV ranged from 0.044 to 0.232 (CV%: 4.4–23.2%) (Figure 5).
Relationships Among Speed, YYIRT, and RHIE Test Performances
Rugby League and Rugby Union Backs
There was a moderate but nonsignificant relationship (r = 0.43; p > 0.05) between RHIE total sprint time and YYIRT in T1 for backs. Relationships between total sprint time and decrement in the RHIE test for backs, over the 3 test periods were r = 0.72 (p < 0.01), r = 0.54 (p < 0.05), and r = 0.34 (p > 0.05) (T1, T2, and T3, respectively). There was no relationship between 20-m sprint times and YYIRT. There was no significant relationship between changes in performance of RHIE total sprint time and YYIRT though improvements in RHIE total sprint time were related to changes in 20-m sprint times (T1 to T2, r = 0.63; T2 to T3, r = 0.69; and T1 to T3,;r = 0.63; all p < 0.05).
Rugby League Forwards
The RHIE total sprint times and performance decrements at 2 of the testing periods were significantly related: r = 0.62 (p < 0. 05) and r = 0.96 (p < 0.01) at T1 and T2, respectively; measures were not related at T3 (r = 0.29; p > 0.05). Weak, nonsignificant relationships were found between changes in performance in RHIE total sprint time and YYIRT.
Rugby Union Forwards
The RHIE total sprint times and performance decrements over the 3 test periods were significantly related (r = 0.98, p < 0.01; r = 0.66, p < 0.05; and r = 0.83, p < 0.01, T1, T2, and T3, respectively). The correlation between 20-m sprint and YYIRT performances over the 3 test periods was not significant. Weak, insignificant relationships were found between changes in performance in RU forwards RHIE total sprint time and YYIRT (T1 to T2, r = 0.44; T2 to T3, r = 0.40; T1 to T3, r = 0.57; all p > 0.05). However, changes in total sprint times and performance decrements between T1 and T2 and T1 and T3 were significantly related r = 0.94 (p < 0.01). There were also significant relationships between improvements in total sprint time and 20-m sprint times (T1 to T2: r = 0.57, p < 0.05; T2 to T3: r = 0.63, p < 0.05; and T1 to T3: r = 0.62, p < 0.05).
Repeated-sprint ability tests alone may underestimate the RHIE demands of the rugby codes (13). An RHIE bout was defined as ≥3 sprints, tackles, scrum, ruck, or maul activities within 21 seconds during the same passage of play (modified from ). Given the frequency of RHIE bouts during competition (2,3) and that these bouts may occur at critical periods of a game (2), a test that replicates these demanding passages of play and assesses the ability of players to perform these RHIE activities, would provide important information on the individual RHIE strengths and weaknesses of players. This study is the first to investigate the reliability and sensitivity of 3 exercise tests designed to capture the intensities and durations of RHIE bouts found for professional RL and RU players. Sensitivity was assessed by tracking training-induced changes in the RHIE test performance over a 10-week period of preseason training in elite RU and RL players. Changes in RHIE test performances were compared with potential improvements in 20-m sprint times and performance on the YYIRT at 3 testing occasions during the preseason training period.
Reliability was assessed by having the players perform the RHIE test twice within 7 days. The ICCs for total sprint time were moderate to high (0.82, 0.97, and 0.94) and CV low (4.2, 1.4, and 0.6%) for the combined backs, RL forwards, and RU forwards tests, respectively. However, the reliability of sprint performance decrement scores were poorer, with ICC and CV of 0.78, 0.86, and 0.88 and 49.5, 48.2, and 35.8% for the combined backs, RL forwards, and RU forwards, respectively. The reliability values of the present 3 tests are comparable with those reported from other studies that have examined the reliability of repeated sprints for field sports (12,22). The present finding that performance decrement scores were less reliable than total sprint times is consistent with the findings of Fitzsimmons et al. (9), Impellizzeri et al. (12) and Spencer et al. (22) who reported typical error of measurement values for their decrement data as 18.5, 30.2, and 14.9, respectively. Differences in the total time to complete the first set of sprints to the last set of sprints varied across the groups tested. Total sprint times for the backs were the lowest of the 3 groups tested because of the lower number of tackles between sprint sets and also their relatively stronger general sprinting ability. Those who completed the RHIE RL forward test executed 5 tackles between sets of sprints, whereas those who completed the RHIE RU forward test had the greatest performance decrement over sprinting time. The RHIE RU forward test involved a repeated weighted scrum sled drill and this likely resulted in greater fatigue.
The CV for total sprint times for the 2 trials for the backs, RL forwards, and RU forwards were similar to those of Wragg et al. (24) who tested 7 national-level student soccer players and reported CV of 1.8 and 2.1% for the ‘Bangsbo Sprint Test’ and ‘Maximal Anaerobic Running Test’ (MART), respectively. The Bangsbo Sprint Test involves seven 34-m sprints with an agility component and a 25-second jog recovery (4), whereas the MART test was completed on a treadmill and involved 20-second runs (with 100 seconds of recovery) of increasing speeds until the athlete could no longer perform the 20-second effort.
For all groups, the current data reflect considerable fatigue as a result of the test demands. For example, the players in the RHIE back test group were 1.6 seconds slower in the final set of 3 sprints when compared with the first sprint set. This deficit in total sprint time would result in the backs covering a total of 9 m less (based on the mean minimum velocity of 5.6 m·s−1 performed by backs) over the 3 sprints compared with the beginning of the RHIE. Similarly, not only were the players who completed the RL forwards test on average 2 seconds slower in the final sprint set, but they covered a total of 10 m less (based on the mean minimum velocity of 5.4 m·s−1 performed by RL forwards), which was possible at the beginning of the RHIE test. The greatest deficit in sprint times were found for those who completed the RU forwards test; the deficit of 3.3 seconds resulted in players covering 17 m less (based on the mean minimum velocity of 5.1 m·s−1) over the 3 sprints, which was able to be performed at the beginning of the RHIE test.
The decrement in sprint times found across the 3 tests suggests that those who completed the RU forwards test were placed under greater physiological stress than those who completed the backs test and RL forwards test, and this is likely because of the scrummaging involved in the RU forwards test. Nonetheless, including tackles between sprints did result in fatigue and an increase in sprint times, as the inclusion of 5 tackles produced a greater deficit in sprint times than the 2 tackles included in the backs RHIE test. Comparison of total sprint time and assessment of fatigue through sprint performance decrement are the most common means of evaluating repeated-sprint performance (9,12,19,23,24). In this study, the use of total sprint time over the nine 20-m sprints emerged as being more reliable than decrement in sprint scores. A coach should essentially be interested in the ability of the player to repeatedly produce maximal sprint efforts, which appears to be more reliably reflected by the mean (or total) sprint time.
The study found significant improvements in total sprint times for the RHIE test for all the groups over the training period. Small to large improvements in 20-m sprint performance were found for all groups. Although RHIE test performance (i.e., total time) was related to YYIRT performance and 20-m sprint times at some time points, for some groups, the low common variance among tests suggests that the RHIE tests were assessing different capacities and abilities to those evaluated by the YYIRT and the 20-m sprint. Higher and statistically significant associations were found between 20-m sprint times and RHIE total sprint times. These findings are consistent with those reported by Wadley and Le Rossignol (23) who found significant correlations (r = 0.83) between total sprint time (sum of twelve 20 m sprints) and best 20-m sprint time in elite Australian football players. Pyne et al. (20) also found a moderate but significant relationship (r = 0.66) between total sprint time (for six 20-m repeated sprints on a 20 s cycle) and the fastest 20-m sprint, in junior Australian football players. Although the common variance between RHIE and speed tests was only around 50%, the significant association observed in this study and from the investigations of others (Wadley and Le Rossignol ; Pyne et al. ) collectively suggest that those players who are quickest over 20 m are also those who perform best in multiple sprints.
In a series of studies, Krustrup et al. (15,16) examined changes in the YYIRT over 8 weeks of preseason training in professional soccer players. A 25% increase in performance (similar to the magnitude of changes found for the present groups) was found in YYIRT level 1 (15), whereas a 42% improvement was reported in YYIRT level 2 (16). The YYIRT performance in this study was substantially higher than that reported by Krustrup et al. (16). The present improvements in the YYIRT found for the 3 groups suggest that the training programs followed by the players over the 10 weeks were effective in improving high-intensity intermittent running ability.
There is no accepted benchmark against which to establish the criterion sensitivity of sprint tests. Previous research studies (9,12,22,24) have taken similar repeated-sprint protocols with sprint durations varying between 20 and 40 m and a passive or active recovery ranging from 15 to 30 seconds. The tests undertaken in this study seem to reliably measure a component of high physical demand found for elite RL and RU players. The RU forwards showed the greatest improvements in RHIE total sprint time over the testing period (6.8%). This is also true for RU forwards 20-m sprint times improving twice as much as other positions. This may have been because of a lower level of initial conditioning (given that the RU forwards were semiprofessional and not professional players). The present findings on 20-m sprint times, are consistent with those reported by Impellizzeri et al. (12) who reported a 1% improvement in 30-m sprint times in professional soccer players after a 12 week preseason training period. It is possible to conclude that the present training regimes followed by the 3 groups of players in this study were effective in improving sprint and repeated-sprint ability.
This study has shown that the 3 tests devised from time motion analysis data and which reflect the most demanding passages of play for elite RU and RL players have moderate to high reliability when total sprint times are compared. Predictably, the greater the number of tackles performed by players, and the inclusion of a scrummaging drill resulted in greater decrements in sprint times. Our findings also demonstrate that the test possesses adequate sensitivity to detect training-induced changes in RHIE ability. The tests examined in this study can be used by coaches in RL and RU to assess the preparedness of their players to meet the most demanding passages of play likely to be experienced in competition. The tests allow coaches to measure a player's ability to recover from either tackling or scrummaging and maintain high-intensity running ability. If the players are able to decrease their total sprint time, there has been an adaptation to an RHIE specific to their playing position and rugby code.
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