International Journal of Sports Physiology and Performance, 2015, 10, 767 -773 http://dx.doi.org/10.1123/ijspp.2015-0100 © 2015 Human Kinetics, Inc.
Original Investigation
The Impact of 3 Different-Length Between-Matches Microcycles on Training Loads in Professional Rugby League Players Alexandre Moreira, Tom Kempton, Marcelo Saldanha Aoki, Anita C. Sirotic, and Aaron J. Coutts Purpose: To examine the impact of varying between-matches microcycles on training characteristics (ie, intensity, duration, and load) in professional rugby league players and to report on match load related to these between-matches microcycles. Methods: Training-load data were collected during a 26-wk competition period of an entire season. Training load was measured using the session rating of perceived exertion (session-RPE) method for every training session and match from 44 professional rugby league players from the same National Rugby League team. Using the category-ratio 10 RPE scale, the training intensity was divided into 3 zones (low 7 AU). Three different-length between-matches recovery microcycles were used for analysis: 5–6 d, 7–8 d, and 9–10 d. Results: A total of 3848 individual sessions were recorded. During the shorter-length between-matches microcycles (5–6 d), significantly lower training load was observed. No significant differences for subsequent match load or intensity were identified between the various match recovery periods. Overall, 16% of the training sessions were completed at the low-intensity zone, 61% at the moderate-intensity zone, and 23% at the high-intensity zone. Conclusions: The findings demonstrate that rugby league players undertake higher training load as the length of between-matches microcycles is increased. The majority of in-season training of professional rugby league players was at moderate intensity, and a polarized approach to training that has been reported in elite endurance athletes does not occur in professional rugby league. Keywords: team sports, monitoring training, ratings of perceived exertion, periodization, session-RPE Professional rugby league players undertake different forms of training to improve distinct physical and technical attributes needed for match performance during a season.1 During a competitive season (~6 mo) players usually participate in an official match each week. As a result of this competition schedule, it is a challenge for coaches to find the balance between applying appropriate training loads and recovery strategies between matches.2 Indeed, high levels of fatigue or incomplete recovery may affect performance, and if the fatigue-recovery balance is not managed appropriately, athletes may be at greater risk of underperformance and/or injury.3 While it is widely accepted that appropriate periodization of between-matches training load is important in professional rugby league players, relatively few studies have examined the influence of training distribution during weekly microcycles and its impact on performance and/or injury.4–6 It is also unclear how different-length between-matches microcycles affect the organization of training or subsequent match performance. Murray et al7 recently reported that the activity profiles of professional rugby league match play and the injury rates of specific playing positions are influenced by the amount of recovery between matches. The results of that previous study demonstrated that greater relative total distances were covered after matches involving short (5–6 d), compared with medium (7–8 d) or long (9–10 d), recovery periods. Similarly, injury rates for the adjustables positional group were highest after short betweenmatches recovery cycles, while the injury rates of hit-up forwards
and outside backs were highest after long recovery periods. While these preliminary data show that subsequent performance and injury risk might be affected by the number of days between games, little is known about the effects of different-length between-matches recovery cycles on training prescription. An improved understanding of how elite rugby league players train, with specific focus on the distribution of intensity and influence of different between-matches microcycles, will better inform coaches on optimal training periodization during the inseason period. This information could be used to assist in designing effective training strategies that improve physical performance and reduce injury risk.7 Due to its validity as a measure of training load in various types of training,8–11 the training load completed by team-sport athletes is commonly quantified by the session rating of perceived exertion (RPE) method.12,13 Despite its popularity, no study has described how the session-RPE training load and intensity are periodized during the in-season phase in professional rugby league. Specifically, no studies have examined the influence of different-length between-matches microcycles on training-load periodization or examined the impact of these cycles on perceived match load. Therefore, the first aim of this study was to examine the impact of different between-matches microcycles on training characteristics (ie, intensity, duration, and load) in professional rugby league players. The second aim was to report on match load related to these between-matches microcycles, based on the session-RPE method.
The meanMoreira is with the Dept of Sport, School of Physical Education and Sport, and Aoki, the School of Arts, Sciences, and Humanities, University of São Paulo, São Paulo, Brazil. Kempton, Sirotic, and Coutts are with the Sport & Exercise Discipline Group, University of Technology, Sydney (UTS), Sydney, Australia. Address author correspondence to Alexandre Moreira at [email protected].
Methods Subjects Forty-four professional rugby league players from the same National Rugby League team participated in this study. Players were 767
768 Moreira et al
categorized into 3 positional groups in accordance with previous research.7,14 The cohort comprised 21 forwards, 11 adjustables, and 12 outside backs. The characteristics of the participants were as follows: age 23.8 ± 3.2 years, stature 184 ± 4 cm, body mass 98 ± 8 kg. University human research ethics committee approval and written consent were obtained before the commencement of the study.
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Design A prospective longitudinal research design was used for this study. Training-load data were collected during the 26-week competition period. Training load was measured using the session-RPE method for every training session and game. Session-RPE was obtained by asking each player “How intense was your session?” using the CR-10 scale 10 to 30 minutes after each session and game.13,15 All players were familiarized with this RPE scale for monitoring training load during the preseason phase. All data were taken by club staff who were highly familiar with taking session-RPE measures and were then entered into the club’s proprietary training-load database (Smartabase, Fusion Sport, Coopers Plains, Australia).
Between-Matches Microcycles Three varying between-matches recovery microcycles were considered for analysis: 5 to 6 days, 7 to 8 days, and 9 to 10 days.7 Table 2 displays a typical 7-day between-matches microcycle.
Statistical Analyses The assumptions of normality and homoscedasticity were verified using Shapiro-Wilk and Levene tests, respectively. Differences in match load, playing match time, and match intensity, as well as training load and training intensity between forward, adjustable, and outside back playing positions for different-length between-match microcycles, were compared using a 2-way repeated-measures ANOVA. When significant main effects were found, Tukey post hoc analyses were applied to locate the differences. Cohen d effect sizes (ES) were also calculated for the perceptual measures. ES results were interpreted as previously described16 with 0.8 large. An alpha (α) level of 7 AU, Lovell et al13 included all sessions performed at ≥7 AU in their high-intensity classification. The current results concur with those of other studies on teamsport athletes13,18,19 that showed a greater proportion of training sessions completed at moderate and high intensity than reports on endurance athletes.17,20 In contrast to previous research on endurance athletes that has reported a polarized approach to training,17 the distribution of training intensity was skewed toward higherintensity sessions. Possible reasons for the different distribution may be that rugby league players complete much lower overall training and fewer sessions than elite endurance athletes. Indeed, the players in this study completed 3.9 ± 1.3 sessions/wk (excluding matches) with a mean weekly training duration of 2.4 ± 0.1 h/wk, while recent reports of 11 elite cross country skiers and biathletes showed that those elite Nordic endurance athletes completed 8.3 ± 2.1 sessions/wk during the competition phase with a training duration of 11.6 ± 2.1 h/wk.21 Another difference from the research on elite endurance athletes is the requirement for weekly competition in rugby league. This competition schedule demands that players organize their weekly training cycles so that training loads are decreased immediately before and after matches to ensure that they are appropriately recovered.6 Taken collectively, the comparisons of the organization of the training structure of athletes from various sports seem to be greatly influenced by the volume of high-intensity training completed by the athletes, with a greater need for recovery and reduction in total training volume when more-intense training sessions are performed. The differences in intensity distribution between the different training types are another new finding of the current study. The results showed that skill-conditioning sessions were typically the most intense sessions, with ~46% of sessions being reported as high intensity. The skills, wrestling, and conditioning sessions showed a similar distribution of session intensity, with the majority of these sessions being rated as moderate intensity. The training sessions of lowest perceived intensity were the speed and complementary/recovery sessions. The practical utility of this information is that coaches can anticipate the loads endured by different types of training and prospectively plan the expected training loads. Nonetheless, better
understanding of the loads applied to the players during different types of training could also be obtained from microtechnology (ie, GPS and accelerometers) that can provide more specific information on the external loads endured by the players in each of these sessions. This information combined with measures of internal load may provide more holistic information on the dose applied and load experienced by players during these training sessions. Irrespective of the period between matches, the matches provided the greatest load and intensity of all training sessions. The current match-load values were greater than recent reports from professional rugby league players participating in the English Super League, who completed 242 ± 186, 435 ± 158, and 376 ± 129 arbitrary units for forwards, adjustables, and outside backs, respectively.14 Similar to this previous study, we observed that the match loads of the forwards were lower than those of the adjustables and outside backs. These differences were due to shorter match playing time rather than differences in perceived intensity and are in line with most studies on professional rugby league, which showed a complete match playing time of ~80 minutes for outside backs, ~70 minutes for pivots, and ~50 minutes for forwards.1,14,22 The similarities in match intensity between positions could be partly explained by similarities in relative distances covered by players regardless of their position. Despite differences in physical demands between playing positions in rugby league1,22,23—with backs typically covering greater total distances than forwards—it has been shown that they cover similar relative distances (~93–101 m/min) during matches.1 However, there are other demands that may contribute to the perception of effort during match play, such as tackling, collision, repeated-high-intensity efforts, and constant accelerations and decelerations.1,22 It has been suggested that the shorter playing times typically observed in forwards relate to the large number of collisions and greater frequency of high-intensity efforts during competition compared with the other positions.24 However, regardless of the discrete differences in the activity profiles between positions, it has been shown that the session-RPE method provides a valid integrated measure of exercise intensity for rugby league players of all playing positions.13 Despite no differences in match intensity between positions, a moderately higher match intensity (ES = 0.66) was reported in the forwards after the shorter-length between-matches periods than the moderate and longer microcycles. In contrast, the adjustables reported higher match intensity after the moderate microcycles than either the shorter or longer between-matches periods (ES = 1.06). These findings suggest that the between-matches microcycles may affect the perception of effort in match play and that such differences may be considered important in a practical sport setting. In addition, these findings are supported by the recent finding that professional rugby league players covered greater relative total distance after matches involving short recovery than those involving medium or long recovery periods.7 Those authors suggested that the greater speeds were completed by players after shorter between-matches periods in professional rugby league players. However, like the current study, a relatively small sample was used, which makes generalizations difficult. The training loads were lower during the short betweenmatches recovery microcycles than the moderate or long periods, regardless of position. The lower training loads during the short between-matches period may be due to a deliberate strategy from coaching staff to facilitate player recovery. The importance of adequate recovery between matches has been demonstrated by Slattery et al,25 who examined the effect of training load on running performance and plasma markers of anaerobic metabolism,
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muscle damage, and inflammation in 7 male team-sport athletes, using a team-sport match simulation on a nonmotorized treadmill. They showed that after completing a heavy physical training load between matches, anaerobic metabolism and performance capacity (sprint performance) may be impaired. Moreover, after the high-training-load protocol greater muscle damage, reduced blood lactate during the match simulation, and an increased postmatch plasma xanthine oxidase were observed. The findings underline the importance of strategies to promote recovery from intense training and matches in team-sport athletes. Reducing load during periods between matches—in particular, during short periods between matches—appears to be an appropriate strategy to promote recovery. The lower training load observed during the short betweenmatches recovery microcycle in the current study agrees with recent research examining between-matches recovery in professional rugby league.6 Those authors showed a higher daily training load in players during 7- and 9-day between-matches recovery periods than 5-day between-matches microcycles. However, they did not differentiate the training load completed by player position. Taken together, these findings suggest that rugby league coaches manipulate training depending on the number of days between games, with lower loads being undertaken during shorter microcycles between matches. Another interesting result from the current study was the absence of differences in training intensity between the different-length between-matches microcycles. This result suggests that rugby league players complete training sessions following a strategy to promote recovery between matches, focused primarily on the reduction of the training volume. As training load was lower during shorter microcycles between matches but not the training intensity, it could be speculated that reducing training volume while maintaining session intensity may be a usual prescribed recovery strategy by coaches. While the data of the current study provide important foundation information that may be used to better understand the in-season training demands of professional rugby league players, there are limitations that should be acknowledged. Since only 1 team was investigated, the study is considered a case study and therefore the results may only be specific to these players or the club that participated in the study. It is possible that training modes, duration intensity, and training-load distribution may vary between clubs. Another limitation is that we have only described the training dose using the session-RPE method. While this approach has been shown to be valid for many types of training activities, it only describes 1 construct of dose. As highlighted elsewhere,19 other measures of both internal and external training loads (ie, heart rate, data derived from GPS, accelerometers, etc) may provide additional insights into the loads applied to rugby league players. Future studies could investigate the effect of manipulating training-load intensity and recovery practices between matches on the psychobiological recovery and performance measures of professional rugby league players. For example, one could investigate whether reducing intensity during the shorter between-matches microcycles and/or increasing it during longer recovery cycles would affect recovery and physical performance.
Practical Applications The differences in intensity distribution between the training modes observed in this study provide important insight into the training loads experienced by professional rugby league players. These findings can be used by coaches to inform decisions when prescribing
training loads between matches during the in-season. The current findings demonstrate that the majority of training sessions were completed at moderate intensity, and matches were completed at high perceived intensity. These observations suggest that training and recovery activities should be prioritized during the in-season to avoid greater risk of injuries/illnesses and unplanned fatigue. Indeed, systematic approaches to monitoring the training and recovery of all players during the in-season should be adopted. Such approaches would allow coaches to account for individual responses to training and competition and also help players cope with the demands of professional rugby league.
Conclusion The current study demonstrated that lower training loads are undertaken during shorter-length between-matches microcycles by professional rugby league players. It also demonstrated that playing position and length of between-matches periods may influence match intensity. Higher match intensity was observed after the shorter between-matches microcycles for forwards but after the moderate between-matches microcycles for adjustables. Skill-conditioning sessions were typically rated as the most intense, skills, wrestling, and conditioning sessions were mostly rated as moderate intensity; and speed and complementary/recovery were perceived as lower-intensity sessions. Finally, the study revealed that the majority of in-season training of professional rugby league players was conducted at moderate or high intensity. Acknowledgments We would like to thank the CAPES Foundation, Ministry of Education of Brazil (process, BEX 17762/12-0), for an award to the first author. We also wish to acknowledge the University of Technology, Sydney (UTS) for offering the first author an appointment as a visiting fellow at the university and all players and team staff members involved in this study for their committed participation.
References 1. Gabbett TJ, Jenkins DG, Abernethy B. Physical demands of professional rugby league training and competition using microtechnology. J Sci Med Sport. 2012;15(1):80–86. PubMed doi:10.1016/j. jsams.2011.07.004 2. Coutts AJ, Sirotic AC, Knowles H, Catterick C. Monitoring training loads in professional rugby league. In: Reilly T, Korkusuz F, eds. Science and Football VI. London, UK: Routledge; 2009:272–277. 3. Twist C, Highton J. Monitoring fatigue and recovery in rugby league players. Int J Sports Physiol Perform. 2013;8(5):467–474. PubMed 4. Coutts A, Reaburn P, Piva TJ, Murphy A. Changes in selected biochemical, muscular strength, power, and endurance measures during deliberate overreaching and tapering in rugby league players. Int J Sports Med. 2007;28(2):116–124. PubMed doi:10.1055/s-2006-924145 5. Coutts AJ, Reaburn P, Piva TJ, Rowsell GJ. Monitoring for overreaching in rugby league players. Eur J Appl Physiol. 2007;99(3):313–324. PubMed doi:10.1007/s00421-006-0345-z 6. McLean BD, Coutts AJ, Kelly V, McGuigan MR, Cormack SJ. Neuromuscular, endocrine, and perceptual fatigue responses during different length between-match microcycles in professional rugby league players. Int J Sports Physiol Perform. 2010;5(3):367–383. PubMed 7. Murray NB, Gabbett TJ, Chamari K. Effect of different between-match recovery times on the activity profiles and injury rates of National
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Rugby League players. J Strength Cond Res. 2014;28(12):3476–3483. PubMed doi:10.1519/JSC.0000000000000603 8. Alexiou H, Coutts AJ. A comparison of methods used for quantifying internal training load in women soccer players. Int J Sports Physiol Perform. 2008;3(3):320–330. PubMed 9. Impellizzeri FM, Rampinini E, Coutts AJ, Sassi A, Marcora SM. Use of RPE-based training load in soccer. Med Sci Sports Exerc. 2004;36(6):1042–1047. PubMed doi:10.1249/01. MSS.0000128199.23901.2F 10. Scott TJ, Black CR, Quinn J, Coutts AJ. Validity and reliability of the session-RPE method for quantifying training in Australian football: a comparison of the CR10 and CR100 scales. J Strength Cond Res. 2013;27(1):270–276. PubMed doi:10.1519/JSC.0b013e3182541d2e 11. Sweet TW, Foster C, McGuigan MR, Brice G. Quantitation of resistance training using the session rating of perceived exertion method. J Strength Cond Res. 2004;18(4):796–802. PubMed 12. Coutts AJ, Cormack S. Monitoring the training response. In: Joyce D, Lewindon D, eds. High-Performance Training for Sports. Champaign, IL: Human Kinetics; 2014:71–84. 13. Lovell TWJ, Sirotic AC, Impellizzeri FM, Coutts AJ. Factors affecting perception of effort (session rating of perceived exertion) during rugby league training. Int J Sports Physiol Perform. 2013;8(1):62–69. PubMed 14. Waldron M, Twist C, Highton J, Worsfold P, Daniels M. Movement and physiological match demands of elite rugby league using portable global positioning systems. J Sports Sci. 2011;29(11):1223–1230. PubMed doi:10.1080/02640414.2011.587445 15. Foster C, Florhaug JA, Franklin J, et al. A new approach to monitoring exercise training. J Strength Cond Res. 2001;15(1):109–115. PubMed 16. Cohen J. Statistical Power Analysis for the Behavioral Sciences. 2nd ed. Hillsdale, NJ: Lawrence Erlbaum; 1988. 17. Seiler KS, Kjerland GO. Quantifying training intensity distribution in elite endurance athletes: is there evidence for an ‘optimal’
distribution? Scand J Med Sci Sports. 2006;16(1):49–56. PubMed doi:10.1111/j.1600-0838.2004.00418.x 18. Algrøy EA, Hetlelid KJ, Seiler S, Stray Pedersen JI. Quantifying training intensity distribution in a group of Norwegian professional soccer players. Int J Sports Physiol Perform. 2011;6(1):70–81. PubMed 19. Moreira A, Bilsborough JC, Sullivan CJ, Cianciosi M, Aoki MS, Coutts AJ. Training periodization of professional Australian Football players during an entire Australian Football League season. Int J Sports Physiol Perform. 2015;10(5):566–571. http://dx.doi.org/10.1123/ ijspp.2014-0326 20. Seiler S, Tønnessen E. Intervals, thresholds, and long slow distance: the role of intensity and duration in endurance training. Sportscience. 2009;13:32–53. 21. Tønnessen E, Sylta O, Haugen TA, Hem E, Svendsen IS, Seiler S. The road to gold: training and peaking characteristics in the year prior to a gold medal endurance performance. PLoS One. 2014;9(7):e101796 doi:10.1371/journal.pone.0101796. PubMed 22. Sirotic AC, Knowles H, Catterick C, Coutts AJ. Positional match demands of professional rugby league competition. J Strength Cond Res. 2011;25(11):3076–3087. PubMed doi:10.1519/ JSC.0b013e318212dad6 23. Austin DJ, Kelly SJ. Positional differences in professional rugby league match play through the use of global positioning systems. J Strength Cond Res. 2013;27(1):14–19. PubMed doi:10.1519/ JSC.0b013e31824e108c 24. Gabbett TJ, Jenkins DG, Abernethy B. Physical collisions and injury in professional rugby league match-play. J Sci Med Sport. 2011;14(3):210–215. PubMed doi:10.1016/j.jsams.2011.01.002 25. Slattery KM, Wallace LK, Bentley DJ, Coutts AJ. Effect of training load on simulated team sport match performance. Appl Physiol Nutr Metab. 2012;37(2):315–322. PubMed doi:10.1139/h2012-001
IJSPP Vol. 10, No. 6, 2015
Original Investigation
The Impact of 3 Different-Length Between-Matches Microcycles on Training Loads in Professional Rugby League Players Alexandre Moreira, Tom Kempton, Marcelo Saldanha Aoki, Anita C. Sirotic, and Aaron J. Coutts Purpose: To examine the impact of varying between-matches microcycles on training characteristics (ie, intensity, duration, and load) in professional rugby league players and to report on match load related to these between-matches microcycles. Methods: Training-load data were collected during a 26-wk competition period of an entire season. Training load was measured using the session rating of perceived exertion (session-RPE) method for every training session and match from 44 professional rugby league players from the same National Rugby League team. Using the category-ratio 10 RPE scale, the training intensity was divided into 3 zones (low 7 AU). Three different-length between-matches recovery microcycles were used for analysis: 5–6 d, 7–8 d, and 9–10 d. Results: A total of 3848 individual sessions were recorded. During the shorter-length between-matches microcycles (5–6 d), significantly lower training load was observed. No significant differences for subsequent match load or intensity were identified between the various match recovery periods. Overall, 16% of the training sessions were completed at the low-intensity zone, 61% at the moderate-intensity zone, and 23% at the high-intensity zone. Conclusions: The findings demonstrate that rugby league players undertake higher training load as the length of between-matches microcycles is increased. The majority of in-season training of professional rugby league players was at moderate intensity, and a polarized approach to training that has been reported in elite endurance athletes does not occur in professional rugby league. Keywords: team sports, monitoring training, ratings of perceived exertion, periodization, session-RPE Professional rugby league players undertake different forms of training to improve distinct physical and technical attributes needed for match performance during a season.1 During a competitive season (~6 mo) players usually participate in an official match each week. As a result of this competition schedule, it is a challenge for coaches to find the balance between applying appropriate training loads and recovery strategies between matches.2 Indeed, high levels of fatigue or incomplete recovery may affect performance, and if the fatigue-recovery balance is not managed appropriately, athletes may be at greater risk of underperformance and/or injury.3 While it is widely accepted that appropriate periodization of between-matches training load is important in professional rugby league players, relatively few studies have examined the influence of training distribution during weekly microcycles and its impact on performance and/or injury.4–6 It is also unclear how different-length between-matches microcycles affect the organization of training or subsequent match performance. Murray et al7 recently reported that the activity profiles of professional rugby league match play and the injury rates of specific playing positions are influenced by the amount of recovery between matches. The results of that previous study demonstrated that greater relative total distances were covered after matches involving short (5–6 d), compared with medium (7–8 d) or long (9–10 d), recovery periods. Similarly, injury rates for the adjustables positional group were highest after short betweenmatches recovery cycles, while the injury rates of hit-up forwards
and outside backs were highest after long recovery periods. While these preliminary data show that subsequent performance and injury risk might be affected by the number of days between games, little is known about the effects of different-length between-matches recovery cycles on training prescription. An improved understanding of how elite rugby league players train, with specific focus on the distribution of intensity and influence of different between-matches microcycles, will better inform coaches on optimal training periodization during the inseason period. This information could be used to assist in designing effective training strategies that improve physical performance and reduce injury risk.7 Due to its validity as a measure of training load in various types of training,8–11 the training load completed by team-sport athletes is commonly quantified by the session rating of perceived exertion (RPE) method.12,13 Despite its popularity, no study has described how the session-RPE training load and intensity are periodized during the in-season phase in professional rugby league. Specifically, no studies have examined the influence of different-length between-matches microcycles on training-load periodization or examined the impact of these cycles on perceived match load. Therefore, the first aim of this study was to examine the impact of different between-matches microcycles on training characteristics (ie, intensity, duration, and load) in professional rugby league players. The second aim was to report on match load related to these between-matches microcycles, based on the session-RPE method.
The meanMoreira is with the Dept of Sport, School of Physical Education and Sport, and Aoki, the School of Arts, Sciences, and Humanities, University of São Paulo, São Paulo, Brazil. Kempton, Sirotic, and Coutts are with the Sport & Exercise Discipline Group, University of Technology, Sydney (UTS), Sydney, Australia. Address author correspondence to Alexandre Moreira at [email protected].
Methods Subjects Forty-four professional rugby league players from the same National Rugby League team participated in this study. Players were 767
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categorized into 3 positional groups in accordance with previous research.7,14 The cohort comprised 21 forwards, 11 adjustables, and 12 outside backs. The characteristics of the participants were as follows: age 23.8 ± 3.2 years, stature 184 ± 4 cm, body mass 98 ± 8 kg. University human research ethics committee approval and written consent were obtained before the commencement of the study.
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Design A prospective longitudinal research design was used for this study. Training-load data were collected during the 26-week competition period. Training load was measured using the session-RPE method for every training session and game. Session-RPE was obtained by asking each player “How intense was your session?” using the CR-10 scale 10 to 30 minutes after each session and game.13,15 All players were familiarized with this RPE scale for monitoring training load during the preseason phase. All data were taken by club staff who were highly familiar with taking session-RPE measures and were then entered into the club’s proprietary training-load database (Smartabase, Fusion Sport, Coopers Plains, Australia).
Between-Matches Microcycles Three varying between-matches recovery microcycles were considered for analysis: 5 to 6 days, 7 to 8 days, and 9 to 10 days.7 Table 2 displays a typical 7-day between-matches microcycle.
Statistical Analyses The assumptions of normality and homoscedasticity were verified using Shapiro-Wilk and Levene tests, respectively. Differences in match load, playing match time, and match intensity, as well as training load and training intensity between forward, adjustable, and outside back playing positions for different-length between-match microcycles, were compared using a 2-way repeated-measures ANOVA. When significant main effects were found, Tukey post hoc analyses were applied to locate the differences. Cohen d effect sizes (ES) were also calculated for the perceptual measures. ES results were interpreted as previously described16 with 0.8 large. An alpha (α) level of 7 AU, Lovell et al13 included all sessions performed at ≥7 AU in their high-intensity classification. The current results concur with those of other studies on teamsport athletes13,18,19 that showed a greater proportion of training sessions completed at moderate and high intensity than reports on endurance athletes.17,20 In contrast to previous research on endurance athletes that has reported a polarized approach to training,17 the distribution of training intensity was skewed toward higherintensity sessions. Possible reasons for the different distribution may be that rugby league players complete much lower overall training and fewer sessions than elite endurance athletes. Indeed, the players in this study completed 3.9 ± 1.3 sessions/wk (excluding matches) with a mean weekly training duration of 2.4 ± 0.1 h/wk, while recent reports of 11 elite cross country skiers and biathletes showed that those elite Nordic endurance athletes completed 8.3 ± 2.1 sessions/wk during the competition phase with a training duration of 11.6 ± 2.1 h/wk.21 Another difference from the research on elite endurance athletes is the requirement for weekly competition in rugby league. This competition schedule demands that players organize their weekly training cycles so that training loads are decreased immediately before and after matches to ensure that they are appropriately recovered.6 Taken collectively, the comparisons of the organization of the training structure of athletes from various sports seem to be greatly influenced by the volume of high-intensity training completed by the athletes, with a greater need for recovery and reduction in total training volume when more-intense training sessions are performed. The differences in intensity distribution between the different training types are another new finding of the current study. The results showed that skill-conditioning sessions were typically the most intense sessions, with ~46% of sessions being reported as high intensity. The skills, wrestling, and conditioning sessions showed a similar distribution of session intensity, with the majority of these sessions being rated as moderate intensity. The training sessions of lowest perceived intensity were the speed and complementary/recovery sessions. The practical utility of this information is that coaches can anticipate the loads endured by different types of training and prospectively plan the expected training loads. Nonetheless, better
understanding of the loads applied to the players during different types of training could also be obtained from microtechnology (ie, GPS and accelerometers) that can provide more specific information on the external loads endured by the players in each of these sessions. This information combined with measures of internal load may provide more holistic information on the dose applied and load experienced by players during these training sessions. Irrespective of the period between matches, the matches provided the greatest load and intensity of all training sessions. The current match-load values were greater than recent reports from professional rugby league players participating in the English Super League, who completed 242 ± 186, 435 ± 158, and 376 ± 129 arbitrary units for forwards, adjustables, and outside backs, respectively.14 Similar to this previous study, we observed that the match loads of the forwards were lower than those of the adjustables and outside backs. These differences were due to shorter match playing time rather than differences in perceived intensity and are in line with most studies on professional rugby league, which showed a complete match playing time of ~80 minutes for outside backs, ~70 minutes for pivots, and ~50 minutes for forwards.1,14,22 The similarities in match intensity between positions could be partly explained by similarities in relative distances covered by players regardless of their position. Despite differences in physical demands between playing positions in rugby league1,22,23—with backs typically covering greater total distances than forwards—it has been shown that they cover similar relative distances (~93–101 m/min) during matches.1 However, there are other demands that may contribute to the perception of effort during match play, such as tackling, collision, repeated-high-intensity efforts, and constant accelerations and decelerations.1,22 It has been suggested that the shorter playing times typically observed in forwards relate to the large number of collisions and greater frequency of high-intensity efforts during competition compared with the other positions.24 However, regardless of the discrete differences in the activity profiles between positions, it has been shown that the session-RPE method provides a valid integrated measure of exercise intensity for rugby league players of all playing positions.13 Despite no differences in match intensity between positions, a moderately higher match intensity (ES = 0.66) was reported in the forwards after the shorter-length between-matches periods than the moderate and longer microcycles. In contrast, the adjustables reported higher match intensity after the moderate microcycles than either the shorter or longer between-matches periods (ES = 1.06). These findings suggest that the between-matches microcycles may affect the perception of effort in match play and that such differences may be considered important in a practical sport setting. In addition, these findings are supported by the recent finding that professional rugby league players covered greater relative total distance after matches involving short recovery than those involving medium or long recovery periods.7 Those authors suggested that the greater speeds were completed by players after shorter between-matches periods in professional rugby league players. However, like the current study, a relatively small sample was used, which makes generalizations difficult. The training loads were lower during the short betweenmatches recovery microcycles than the moderate or long periods, regardless of position. The lower training loads during the short between-matches period may be due to a deliberate strategy from coaching staff to facilitate player recovery. The importance of adequate recovery between matches has been demonstrated by Slattery et al,25 who examined the effect of training load on running performance and plasma markers of anaerobic metabolism,
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muscle damage, and inflammation in 7 male team-sport athletes, using a team-sport match simulation on a nonmotorized treadmill. They showed that after completing a heavy physical training load between matches, anaerobic metabolism and performance capacity (sprint performance) may be impaired. Moreover, after the high-training-load protocol greater muscle damage, reduced blood lactate during the match simulation, and an increased postmatch plasma xanthine oxidase were observed. The findings underline the importance of strategies to promote recovery from intense training and matches in team-sport athletes. Reducing load during periods between matches—in particular, during short periods between matches—appears to be an appropriate strategy to promote recovery. The lower training load observed during the short betweenmatches recovery microcycle in the current study agrees with recent research examining between-matches recovery in professional rugby league.6 Those authors showed a higher daily training load in players during 7- and 9-day between-matches recovery periods than 5-day between-matches microcycles. However, they did not differentiate the training load completed by player position. Taken together, these findings suggest that rugby league coaches manipulate training depending on the number of days between games, with lower loads being undertaken during shorter microcycles between matches. Another interesting result from the current study was the absence of differences in training intensity between the different-length between-matches microcycles. This result suggests that rugby league players complete training sessions following a strategy to promote recovery between matches, focused primarily on the reduction of the training volume. As training load was lower during shorter microcycles between matches but not the training intensity, it could be speculated that reducing training volume while maintaining session intensity may be a usual prescribed recovery strategy by coaches. While the data of the current study provide important foundation information that may be used to better understand the in-season training demands of professional rugby league players, there are limitations that should be acknowledged. Since only 1 team was investigated, the study is considered a case study and therefore the results may only be specific to these players or the club that participated in the study. It is possible that training modes, duration intensity, and training-load distribution may vary between clubs. Another limitation is that we have only described the training dose using the session-RPE method. While this approach has been shown to be valid for many types of training activities, it only describes 1 construct of dose. As highlighted elsewhere,19 other measures of both internal and external training loads (ie, heart rate, data derived from GPS, accelerometers, etc) may provide additional insights into the loads applied to rugby league players. Future studies could investigate the effect of manipulating training-load intensity and recovery practices between matches on the psychobiological recovery and performance measures of professional rugby league players. For example, one could investigate whether reducing intensity during the shorter between-matches microcycles and/or increasing it during longer recovery cycles would affect recovery and physical performance.
Practical Applications The differences in intensity distribution between the training modes observed in this study provide important insight into the training loads experienced by professional rugby league players. These findings can be used by coaches to inform decisions when prescribing
training loads between matches during the in-season. The current findings demonstrate that the majority of training sessions were completed at moderate intensity, and matches were completed at high perceived intensity. These observations suggest that training and recovery activities should be prioritized during the in-season to avoid greater risk of injuries/illnesses and unplanned fatigue. Indeed, systematic approaches to monitoring the training and recovery of all players during the in-season should be adopted. Such approaches would allow coaches to account for individual responses to training and competition and also help players cope with the demands of professional rugby league.
Conclusion The current study demonstrated that lower training loads are undertaken during shorter-length between-matches microcycles by professional rugby league players. It also demonstrated that playing position and length of between-matches periods may influence match intensity. Higher match intensity was observed after the shorter between-matches microcycles for forwards but after the moderate between-matches microcycles for adjustables. Skill-conditioning sessions were typically rated as the most intense, skills, wrestling, and conditioning sessions were mostly rated as moderate intensity; and speed and complementary/recovery were perceived as lower-intensity sessions. Finally, the study revealed that the majority of in-season training of professional rugby league players was conducted at moderate or high intensity. Acknowledgments We would like to thank the CAPES Foundation, Ministry of Education of Brazil (process, BEX 17762/12-0), for an award to the first author. We also wish to acknowledge the University of Technology, Sydney (UTS) for offering the first author an appointment as a visiting fellow at the university and all players and team staff members involved in this study for their committed participation.
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