Previous time motion analyses have confirmed that rugby league match play is intermittent in nature, including bouts of low-intensity activity, such as walking and jogging, interspersed with bouts of high intense activity, such as accelerations, rapid changes of directions, and challenging physical contest (1,2). Because of the nature of these activities, high speed, high repeated sprint ability, and high maximal aerobic power are physical attributes required to play rugby league at the highest level (1,2). In recent years, small-sided games (SSGs) have been extensively used in team sports as a method to improve the physical attributes and fitness, and the technical and tactical skills, of players. This is because SSG involves activities and intensity levels that occur during both traditional conditioning training and match play. Indeed, Gabbett et al. (11) reported that a single bout of SSG had effort demands that were similar to a professional rugby league match play. In another study with rugby league players (7), heart rate and blood lactates levels were shown to be similar during match play and a single bout of SSG. Interestingly, SSG have also been shown to simulate heart rate intensities elicited during traditional interval training (13,19), which is effective in improving aerobic performance (12,13). Therefore, SSGs provide a specific training stimulus that mirrors both the demands of match play and traditional conditioning training.
In addition to providing a training stimulus, SSGs have been shown to improve the repeated sprint ability (17), speed (8,17) and VO2max (8,17) of soccer (17) and rugby league players (8) when performed for several weeks. They have also proven to be as effective as traditional conditioning training for improving the fitness level of adolescent elite handball (5) and soccer players (14). Collectively, these aforementioned studies confirm that long-term SSG interventions offer an effective and activity-specific method for improving the physical attributes and conditioning levels of team sport players. To the best of our knowledge, however, no studies have assessed the effects of SSG training on the repeated sprint ability of rugby league players. Therefore, the aim of this study was to examine the changes in repeat sprint ability (RSA), along with speed and intermittent shuttle running performance of elite rugby league players after an 8-week SSG training intervention. It was hypothesized that RSA, speed, and intermittent shuttle running performance would be increased after the SSG training intervention.
Experimental Approach to the Problem
The 8-week training intervention took place during the competitive phase of the season and consisted of 2 sessions per week. To assess the effects of the training intervention on the physical performance of the players, each player's anthropometry, intermittent shuttle running performance, speed, and RSA were evaluated pre- and postintervention. The testing sessions took place on the same ground and at the same time of the day to standardize the conditions pre- and postintervention. Anthropometry and RSA (morning) and speed (afternoon) were assessed on day 1, whereas aerobic fitness (30-15 Intermittent Fitness Test; 30-15 IFT) was assessed on day 2 (morning). All the running tests were completed, while wearing rugby boots, on a rugby field, and after completing a standardized warm-up that included activities of increasing intensity and stretching exercises. Throughout the testing sessions, all players were encouraged to drink water regularly to maintain their hydration status. They were also required to abstain from taking any stimulants or depressants, including caffeine for at least 6 hours and alcohol for at least 24 hours before the testing sessions. All players were fully familiarized with the tests, as they were part of their standard fitness testing and conditioning sessions. During the training intervention, a typical training week included 5 hours of skills and tactical training, 2 hours of SSG, 2 hours of resistance training (hypertrophy), and 1 hour dedicated to injury prevention and recovery. No speed, RSA, or traditional high-intensity interval training (HIIT) were carried out during the training intervention.
Ten rugby league players who were members of a Stobart Super League team academy volunteered for this investigation (Table 1). Before participating in the training intervention, each player was informed of the aims, benefits, risks, and procedures of the study and signed informed consent documents. The study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of the University Pablo de Olavide, Seville, Spain.
Small-sided Game Intervention
A total of 16 SSGs were played by the players, and 7 different SSGs were used throughout the 8-week training intervention. Two SSGs were specifically designed for the forwards, 2 were designed for the backs, and 3 were designed for both the forwards and the backs. All SSGs involved specific skills and situations that are likely to happen during a game, such as catching, passing, kicking, and carrying the ball, wrestling with and tackling an opponent, attacking or defending own try-line and supporting the play. Players received verbal encouragement by their coaches and, strength and conditioning coaches to promote a high intensity of exercise during each SSG. Each session lasted approximately an hour and consisted of four 10-minute blocks of one SSG. A 3-minute recovery period was given between each block to provide feedback to the players about the previous block, provide details of the next block, and allow them to consume water. All sessions were preceded by a 10-minute standardized warm-up, including athletics drills and dynamic stretching.
Height and body mass were measured using a calibrated Tanita stadiometer (model Leicester, Seca Ltd, Birmingham, United Kingdom) and a Tanita scale (model BC-418MA, Tanita Corporation, Tokyo, Japan), respectively. Before being weighted, the players were allowed to empty their bladder and bowel, if necessary. The average of 2 measures was used to represent each variable. The interclass correlation coefficient for the height and body mass were 0.97and 0.97, respectively.
Intermittent Shuttle Running Performance
To assess intermittent shuttle running performance, the players performed the 30-15 IFT, which involves performing 30-second shuttle runs on a 40-m track interspersed with a 15-second passive recovery (3). The players' velocity is increased by 0.5 km·h−1 at each stage, and the test ends when the player is unable to maintain the imposed running speed or when he fails to reach a 3-m zone on 3 consecutive occasions. The velocity (V) attained during the last completed stage is taken as representative of the participant's VIFT.
Before the beginning of the speed test, the players performed a standardized warm-up that consisted of 3 minutes of athletic drills (e.g., high knees, heel kicks, cariocas, lateral shuffles, skipping, lunges, straight leg march, and internal-external hip rotation), 2 minutes of dynamic stretching, 5 bursts of progressive accelerations over a 20-m distance and 2 maximal sprints over 40 m with 2 minutes recovery between each sprint (4). Two minutes after the last sprint, the speed test started. Speed was measured using electronic timing gates (Microgate photocell, Bolzano, Italy) positioned at 10, 20, and 40 m from a predetermined line. Two trials interspersed with a 2-minute recovery period were performed for a 40-m distance with the fastest 10-, 20-, and 40-m times used as the speed scores. The players began each trial in their own time, starting from a self-selected semi-crouched position, with their front foot approximately 20 cm from the start line. They received verbal encouragements during each trial to elicit maximal effort. The interclass correlation coefficient for the 10-, 20-, and 40-m sprints were 0.91, 0.90, and 0.90, respectively.
Repeated Sprint Ability Performance
Before the RSA test, the players performed a standardized warm-up consisting of athletic drills, dynamic stretching, and bursts of progressive accelerations as described above. The bursts of progressive acceleration were followed by 2 maximal 20-m sprints with 2 minutes recovery in between the sprints. Two minutes after the second maximal 20-m sprint, the players performed the RSA test that consisted of performing 8 maximal linear sprints departing every 20 seconds. At the end of each sprint, the players were asked to run back to the starting gate at a moderate speed to assume the starting position 3 seconds before the next sprint. They were given the countdown “5-4-3-2-1-GO!” before starting. The players were required to run as fast as possible for the 20-m distance and received verbal encouragement during each sprint. Sprint time was measured using electronic timing gates (Microgate photocell), which were placed at the start and at 20 m. Each participant started from a self-selected semi-crouched position with his front foot approximately 20 cm behind the starting gate. Repeat sprint ability was represented by the best sprint time (BST), the mean sprint time (MST), the total sprint time (TST), and the percentage of sprint decrement (% Dec; 100 − (total time/ideal time × 100), where the ideal time = 8 × BST) (10).
Mean and SD data were calculated for the outcome variables described above. Before using the t-test, the normal distribution of the data was examined using the Kolmogorov-Smirnov test. A series of paired samples t-test was then used to assess whether there were any significant differences on the outcome variables before and after the SSG training intervention period. The statistical analyses were conduced using Stata 9 for Windows with the significance level set at p ≤ 0.05.
Table 1 shows the intermittent shuttle running, speed, and RSA performance, before and after the 8-week SSG training intervention. There were significant improvements in intermittent shuttle running performance, as indicated by a greater VIFT score (+1.29%; p = 0.05; effect size [ES] = 1.01), and in 10-m (−3.17%; p = 0.003; ES = 12.99), 20-m (−1.37%; p = 0.002; ES = 10.08), and 40-m sprint times (−0.96%; p = 0.001; ES = 6.33) after the SSG training intervention period. There was also significant improvement in RSA as indicated by a greater MST (−2.11%; p = 0.001; ES = 6.48), TST (−2.11%; p = 0.001; ES = 0.81), and % Dec (7.10 vs. 5.93%; p = 0.05; ES = 0.27), after the intervention (Table 2).
To our knowledge, this study is the first to examine changes in intermittent shuttle running performance, speed, and RSA displayed by elite rugby league players after an 8-week SSG training intervention. In agreement with our hypothesis, the results showed that intermittent shuttle running, speed, and RSA performance significantly improved after the SSG training intervention (Table 2), and the implications of these findings are discussed below.
These results are consistent with the findings of previous studies that have investigated changes in athletic performance after SSG training interventions. Regarding changes in intermittent shuttle running performance measured with the VIFT, Buchheit et al. (5) reported a 6.3% increase of the VIFT score of adolescent handball players after a 10-week SSG training intervention period. The results of the present study show a lower increase (+1.29%) of the players' VIFT score after the SSG training intervention. The initial VIFT score of the players in the present study, which was higher compared with the players in Buchheit et al. (5) study, might explain this discrepancy as it has been previously shown that the magnitude of the response to exercise training induced adaptations is inversely proportional to the initial training status of the athletes (16,18). Moreover, it is unclear whether SSG or traditional conditioning alone or a combination of SSG and traditional conditioning is more effective at improving the physical performance of athletes. Dupont et al. (6) compared the effects of SSG vs. traditional HIIT on maximal aerobic speed during the competitive phase of the season of professional soccer players and results showed an 8.1% increase after the HIIT protocol while no changes were observed after the SSG protocol. This finding might explain the relative small increase of the players' VIFT score observed in the present study after the SSG intervention as no traditional HIIT sessions were included during the 8-week training intervention.
Considering speed performance, Gabbett (8) reported decreases of 5.23, 3.15, and 2.86% of 10-, 20-, and 40-m sprint times, respectively, after a 9-week SSG training intervention with rugby league players. Although of similar duration, the present training intervention induced smaller improvements in the 10-m (−3.17%), 20-m (−1.37%;), and 40-m (−0.96%) sprint times. It has been previously shown that the exercise demand of SSG is influenced by several parameters, such as the number of players on the field, the field dimensions, and the nature of the game itself. For example, Kennett et al. (15) reported that the total number of sprints performed by rugby union players during a SSG was different when comparing a 4 vs. 4 with an 8 vs. 8 and when comparing a smaller with a larger field size. Gabbett et al. (9) observed different sprinting patterns when comparing SSG performed on a 10 × 70-m vs. a 40 × 70-m field. Gabbett et al. (10) examined the demands of 2 rugby league SSGs of different nature while the number of players and the field size remained unaltered. It was found that the total number of high-intensity efforts performed by the players was different between the 2 SGGs. We speculate that the SSGs used in the present study elicited different demands than those of Gabbett (8) and, therefore, are likely to have induced different physiological and physical adaptations as that of the magnitude of training adaptations has been shown to be related to the intensity and volume of training stimulus (18).
The present study is the first to demonstrate that a rugby league–specific SSG training intervention can induce significant improvement in RSA. Indeed, greater MST (−2.11%), TST (−2.11%), and % Dec (7.10 vs. 5.93%) were observed after the 8-week training intervention period. It is likely that the type of SSG undertaken by the players in the present study produced an efficient training stimulus that induced improvement in RSA. Improvements in RSA after a SSG training intervention have been previously reported by Buchheit et al. (5) who observed a 4.63% increase of MST and a greater % Dec (4.10% preintervention to 3.34% postintervention) after a 10-week handball-specific SSG training intervention period. Similarly, Owen et al. (17) observed a 1.84% increase of TST during a RSA test after a 4-week SSG training intervention with soccer players. Unfortunately, as the present study was conducted during the competitive phase of the season, all the players of the squad were training with the aim of being selected to play the next championship game, and no control group could be included in this investigation. Therefore, the findings of the present study must be interpreted with caution as changes in physical performance observed after the SSG training intervention period could have been influenced by the technical and tactical trainings undertook by the players. However, it is worth noting that the SSGs were the only form of conditioning performed during this period.
In conclusion, the results of the present study show for the first time that an 8-week SSG training intervention, conducted in conjunction with technical and tactical training, can concurrently train and improve the intermittent shuttle running, speed, and RSA performance of rugby league players during their competitive season. However, the inclusion of a control group is required in further studies to eliminate the possible contribution of the technical and tactical training in the changes of physical performance. Further studies are also warranted, to determine whether a combination of traditional conditioning and SSG conditioning is more effective at improving the physical level of rugby league players than either traditional conditioning or SSG conditioning alone.
Rugby league coaches and strength and conditioning coaches can use SSG during the preparation phase of a rugby league season to improve the aerobic level, speed level, and repeated sprint ability of their players.
Small-sided games also provide a specific alternative to traditional conditioning for improving the physical level of rugby league players.
Small-sided games offer an effective method to simultaneously train 3 important physical qualities for rugby league players, which is particularly of interest during congested training and playing schedules.
The authors would like to acknowledge the technical staff and the players for their collaboration in this study. The authors thank Professor Julie Steele for her valuable suggestions. There is no financial support for this project. No funds were received for this study from National Institutes of Health, Welcome Trust, University or others.
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