The physical demands of elite English rugby union

The aim of this study was to assess the physical demands of elite English rugby union match-play. Player movements were captured by five distributed video cameras and then reconstructed on a two-dimensional plane representing the pitch. Movements based on speeds were categorized as standing, walking, jogging, and medium-intensity running (low-intensity activity), and high-intensity running, sprinting, and static exertion (scrummaging, rucking, mauling, and tackling) (high-intensity activity). Position groups were defined as forwards (tight and loose) and backs (inside and outside). Backs travelled more total distance than forwards (6127 m, s=724 vs. 5581 m, s=692; P<0.05) and greater distances in walking (2351 m, s=287 vs. 1928 m, s=2342; P<0.001) and high-intensity running (448 m, s=149 vs. 298 m, s=107; P<0.05). Forwards performed more high-intensity activity than backs (9:09 min:s, s=1:39 vs. 3:04 min:s, s=1:01; P<0.001), which was attributable to more time spent in static exertion (7:56 min:s, s=1:56 vs. 1:18 min:s, s=0:30; P<0.001), although backs spent more time in high-intensity running (0:52 min:s, s=0:19 vs. 1:19 min:s, s=0:26; P=0.004). Players travelled a greater distance in the first 10 min compared with 50-60 and 70-80 min, but there was no difference in the amount of high-intensity activity performed during consecutive 10-min periods during match-play. These results show the differing physical demands between forwards and backs with no evident deterioration in high-intensity activity performed during match-play.     

Fluctuations in running and skill-related performance in elite rugby union match-play

This study investigated end-game and transient changes in running activities and whether these were concomitantly associated with reductions in skill-related performance in senior international rugby union match-play. Altogether, 18 official matches were analysed (322 individual observations) using computerised video-based tracking and event coding (Amisco Pro^®, SUP, Nice, France). In forwards and backs, trivial to small reductions (% difference: ?2.1, ±1.3 to ?10.0, ±4.0%) in total distance and that covered at high speeds (>18.0?km?h^?1) occurred in the second- versus the first-half while there were trivial differences in skill-related performance measures (?2.3, ±4.5 to 7.5, ±14.0%). In both positions, small to moderate declines (?42, ±10 to ?21, ±7%) occurred in high-speed running in the final 10-min and 5-min periods versus mean values for all other 10-min and 5-min periods throughout the game while only small changes (?18, ±51 to 13, ±41%) in skill-related performance were observed. Trivial changes in running and skill-related performance (?11, ±74 to 7, ±39%) were observed in the 5-min period immediately following the most intense 5-minute periods of play compared to mean performance over the other 5-min periods. These findings suggest that international rugby union players were generally able to maintain skill-related performance over the course of match-play even when declines in running performance occurred.     

Tackle and impact detection in elite Australian football using wearable microsensor technology

Abstract

The effectiveness of a wearable microsensor device (MinimaxX^TM S4, Catapult Innovations, Melbourne, VIC, Australia) to automatically detect tackles and impact events in elite Australian football (AF) was assessed during four matches. Video observation was used as the criterion measure. A total of 352 tackles were observed, with 78% correctly detected as tackles by the manufacturer’s software. Tackles against (i.e. tackled by an opponent) were more accurately detected than tackles made (90% v 66%). Of the 77 tackles that were not detected at all, the majority (74%) were categorised as low-intensity. In contrast, a total of 1510 “tackle” events were detected, with only 18% of these verified as tackles. A further 57% were from contested ball situations involving player contact. The remaining 25% were in general play where no contact was evident; these were significantly lower in peak Player Load? than those involving player contact (P < 0.01). The tackle detection algorithm, developed primarily for rugby, was not suitable for tackle detection in AF. The underlying sensor data may have the potential to detect a range of events within contact sports such as AF, yet to do so is a complex task and requires sophisticated sport and event-specific algorithms.     

An objective method for depicting team performance in elite professional rugby union

Abstract

Using a two-study approach, we examined a methodology for objectively depicting team performance and form in a professional rugby union side. Study 1 developed standardized indicators to examine a team's performance in a single match relative to their previous matches over a domestic season via a performance report and form chart. This resulted in standardized performance indicators that provided instant and coherent feedback on the team's performance relative to previous standards. Study 2 then utilized this methodology to compare a match between two professional sides, played the following season, to assess the extent to which the performance by one team affected that of the other. Comparison of the two teams' performances, for the match they played against each other, identified a drop in relative performance (against previous standards) for both teams on the same performance indicators. This appeared to be due to the match being a close, hard-fought contest particularly in the tackle and around the gain-line. The findings of the two studies suggest an accurate and viable methodology for depicting team performance that is superior to the global measures previously adopted. Presenting teams' current standardized performances (i.e. form) on a single visual scale also has utility for coaches within an applied setting. Future research should further investigate the effect of one team's performance on another through both individual and team outcomes.     

An objective method for depicting team performance in elite professional rugby union

Using a two-study approach, we examined a methodology for objectively depicting team performance and form in a professional rugby union side. Study 1 developed standardized indicators to examine a team's performance in a single match relative to their previous matches over a domestic season via a performance report and form chart. This resulted in standardized performance indicators that provided instant and coherent feedback on the team's performance relative to previous standards. Study 2 then utilized this methodology to compare a match between two professional sides, played the following season, to assess the extent to which the performance by one team affected that of the other. Comparison of the two teams' performances, for the match they played against each other, identified a drop in relative performance (against previous standards) for both teams on the same performance indicators. This appeared to be due to the match being a close, hard-fought contest particularly in the tackle and around the gain-line. The findings of the two studies suggest an accurate and viable methodology for depicting team performance that is superior to the global measures previously adopted. Presenting teams' current standardized performances (i.e. form) on a single visual scale also has utility for coaches within an applied setting. Future research should further investigate the effect of one team's performance on another through both individual and team outcomes.     

Effects of competition on the sleep patterns of elite rugby union players

Abstract

No published research has assessed sleep patterns of elite rugby union players following match-play. The present study examined sleep patterns of professional rugby union players, prior and post-match-play, to assess the influence of competition. Twenty-eight male rugby union players (24.4?±?2.9 years, 103.9?±?12.2?kg) competed in one of four competitive home matches. Player's sleep behaviours were monitored continuously using an Actiwatch^® from two days before the match, until three days post-match. Repeated measures of analysis of variance (ANOVA) showed significant differences across the time points measured for time to bed (F?=?26.425, η² ?=?0.495, p < .001), get up time (F?=?21.175, η²?=?0.440, p?<?.001), time spent in bed (F?=?10.669, η²?=?0.283, p?<?.001), time asleep (F?=?8.752, η²?=?0.245, p?<?.001) and percentage of time moving (F?=?4.602, η²?=?0.146 p?<?.05). Most notable, post hocs revealed a significant increase for time in bed the night before the match (p?<?.01; 95% CI?=?0?:?10–1?:?28?h; 9.7?±?13.5%) compared with the reference night sleep. Furthermore, time asleep significantly decreased post-match (p?<?.05; 95% CI?=??0:03 to ?1:59?h; ?19.5?±?19.8%) compared to two nights pre-match. Across all time points, sleep latency and efficiency for most players were considered abnormal compared to that expected in normal populations. The results demonstrate that sleep that is deprived post-match may have detrimental effects on the recovery process.     

Prevalence of sleep disorders and sleep problems in an elite super rugby union team

The aim of this study was to determine the prevalence of sleep disorders in an elite rugby union team using in-laboratory polysomnography (PSG) and sleep questionnaires. Twenty-five elite rugby union players underwent a night of PSG during the “off-season” of the Super Rugby competition to assess their sleep. Of interest were measurements that detected the presence of obstructive sleep apnea (OSA; apnea-hypopnea index ≥5 events/hr) and the presence of moderate-severe periodic leg movements during sleep (PLMs; ≥15 events/hr). Players completed sleep-related questionnaires to assess daytime sleepiness, perception of insomnia, risk of OSA, and the presence of restless legs syndrome (RLS) and underwent basic anthropometric assessments including body mass index and neck circumference. OSA was present in 24% (n=6) of players and PLMs ≥15 events/hr in 12% (n=3). Questionnaire responses showed that all players had insomnia defined subthreshold insomnia and excessive daytime sleepiness, two players were identified as being at risk for OSA and none were classified as having RLS. In conclusion, sleep disorders and excessive sleepiness are common in elite rugby union players. A process to identify and manage sleep disorders should be considered by teams to optimise their physical recovery, athletic performance and to safeguard their health.     

Body composition characteristics of elite Australian rugby union athletes according to playing position and ethnicity

This study describes the body composition traits of modern-day elite rugby union athletes according to playing position and ethnicity. Thirty-seven international Australian rugby athletes of Caucasian and Polynesian descent undertook body composition assessment using dual-energy X-ray absorptiometry and surface anthropometry. Forwards were significantly taller, heavier and had a greater total fat mass and lean mass than backs. Backs displayed a higher percentage lean mass and lower sum of seven skinfolds and percentage fat mass. While no whole body composition differences were seen between ethnicities, significant regional differences were observed. In the periphery (arm and leg) regions, Polynesians had a greater proportion of fat mass (53.1% vs. 51.3%, P = 0.052, d = 0.5) and lean mass (49.7% vs. 48.6%, P = 0.040, d = 0.9), while in the trunk region a lower proportion of fat mass (37.2% vs. 39.5%, P = 0.019, d = 0.7) and lean mass (45.6% vs. 46.8%, P = 0.020, d = 1.1). Significant differences were also seen between Caucasian and Polynesian forwards in leg lean mass (31.4 kg vs. 35.9 kg, P = 0.014, d = 2.4) and periphery lean mass (43.8 kg vs. 49.6 kg, P = 0.022, d = 2.4). Elite Polynesian rugby athletes have different distribution patterns of fat mass and lean mass compared to Caucasians, which may influence their suitability for particular positions.     

Indices of cognitive function measured in rugby union players using a computer-based test battery

The purpose of this study was to investigate the intra- and inter-day reliability of cognitive performance using a computer-based test battery in team-sport athletes. Eighteen elite male rugby union players (age: 19 ± 0.5 years) performed three experimental trials (T1, T2 and T3) of the test battery: T1 and T2 on the same day and T3, on the following day, 24 h later. The test battery comprised of four cognitive tests assessing the cognitive domains of executive function (Groton Maze Learning Task), psychomotor function (Detection Task), vigilance (Identification Task), visual learning and memory (One Card Learning Task). The intraclass correlation coefficients (ICCs) for the Detection Task, the Identification Task and the One Card Learning Task performance variables ranged from 0.75 to 0.92 when comparing T1 to T2 to assess intraday reliability, and 0.76 to 0.83 when comparing T1 and T3 to assess inter-day reliability. The ICCs for the Groton Maze Learning Task intra- and inter-day reliability were 0.67 and 0.57, respectively. We concluded that the Detection Task, the Identification Task and the One Card Learning Task are reliable measures of psychomotor function, vigilance, visual learning and memory in rugby union players. The reliability of the Groton Maze Learning Task is questionable (mean coefficient of variation (CV) = 19.4%) and, therefore, results should be interpreted with caution.     

A comparison of ratio and allometric scaling methods for normalizing power and strength in elite rugby union players

Abstract

In this study, we compared the effectiveness of ratio and allometric scaling for normalizing power and strength in elite male rugby union players. Rugby union forwards (n = 18) and backs (n = 20) were assessed for squat jump and bench throw peak power, and box squat and bench press one-repetition maximum strength. The performance data for the forwards and backs were compared using ratio (P/BM) and allometric scaling (P/BM^b ), where P represents performance, BM is body mass in kilograms, and b is a power exponent. A proposed allometric exponent (0.67) and exponents (±95% confidence intervals) derived for the box squat (0.33 ± 0.31), bench press (0.45 ± 0.30), bench throw (0.46 ± 0.36), and squat jump (0.64 ± 0.31) exercises were used. In general, the absolute expression of power and strength was superior for the heavier forwards, but after ratio scaling these performance measures then favoured the lighter backs. There were no performance differences between the forwards and backs after allometric scaling using either the proposed or the derived exponents. Thus, allometric scaling may provide a more effective method for normalizing power and strength in elite athletes when body size is a confounding variable.     

Information-governing dynamics of attacker-defender interactions in youth rugby union

Previous work on dynamics of interpersonal interactions in 1 vs. 1 sub-phases of basketball has identified changes in interpersonal distance between an attacker and defender as a potential control parameter for influencing organizational states of attacker-defender dyads. Other studies have reported the constraining effect of relative velocity between an attacker and defender in 1 vs. 1 dyads. To evaluate the relationship between these candidate control parameters, we compared the impact of both interpersonal distance and relative velocity on the pattern-forming dynamics of attacker-defender dyads in the sport of rugby union. Results revealed that when interpersonal distance achieved a critical value of less than 4 m, and relative velocity values increased or were maintained above 1 m x s(-1), a successful outcome (i.e. clean attempt) for an attacker was predicted. Alternatively, when values of relative velocity suddenly decreased below this threshold, at the same critical value of interpersonal distance, a successful outcome for the defender was predicted. Data demonstrated how the coupling of these two potential, nested control parameters moved the dyadic system to phase transitions, characterized as a try or a tackle. Observations suggested that relative velocity increased its influence on the organization of attacker-defender dyads in rugby union over time as spatial proximity to the try line increased.     

Coaches’ perceptions of decision making in rugby union

ABSTRACT

Background: In team games situations, the ability to make fast and accurate decisions is crucial to performance. As such, effective decision making, characterised by the consistent and efficient ability to choose the right course of action at the right moment, is a key component of match performance in team sports such as rugby union. Previous research has identified pedagogical approaches to enhance decision making. However, there is dearth in research to investigate how coaches evaluate tactical decision making and subsequently develop context specific ‘on’ and ‘off-field’ coaching practices to improve it. Further, the value coaches place on decision making is under explored.

Purpose: The aim of this study was to explore coaches’ perceptions of decision making in rugby union. The specific objectives to meet this aim were to: (i) Explore coaches’ perceptions of the value and importance of decision making in rugby union; (ii) Identify coaches’ opinions of the key decision making moments in games and how to evaluate them; and (iii) Investigate coaches’ on and off field methods for improving players’ tactical and strategic decision making.

Participants: Purposive sampling was used to select five male coaches, whose ages ranged from 25 to 41 years, from a regional rugby union club in Wales to participate in the study. Coaching experience ranged from two years to 16 years.

Methods: The interpretative paradigm was used within the study with data collected through semi-structured interviews with academy rugby union coaches. This type of interview gathered rich, detailed and complex accounts of coaches’ opinions of players’ in-game decision making in rugby union in order to inform practice and theory. Inductive and deductive qualitative thematic analysis was used to analyse and interpret the data.

Findings: All five coaches agreed that decision making was a crucial part of the modern game of rugby union. There was some disagreement between them about the players’ autonomy to make their own decisions on the pitch and a general lack of clarity between ‘game plan’, ‘strategy’ and ‘tactics’ amongst the coaches. All the coaches agreed that the process of evaluation of players’ decision making should involve a joint discussion with the players. They also agreed that developing decision making was one of the hardest things to coach. Finally, they used a variety of ‘on’ and ‘off-field’ coaching methods to achieve this including video analysis, questioning and the use of games based scenarios.

Conclusion: This study acquired the coaches’ voice on players’ decision making in rugby union by exploring its perceived importance to them and how they evaluated and attempted to improve it. A clear attempt was made among the coaches to develop a ‘non-judgemental’ atmosphere in the evaluation and improvement of players’ decision making. Future research should consider the use of explicitation interviewing, where the interviewer (coach) aims to get the player into a state of evocation, to relive the key decision making moments in an attempt to improve it.     

The microstructure of coaching practice: behaviours and activities of an elite rugby union head coach during preparation and competition

The activities and behaviours of a female head coach of a national rugby union team were recorded in both training and competition, across a whole rugby season, using the newly developed Rugby Coach Activities and Behaviours Instrument (RCABI). The instrument incorporates 24 categories of behaviour, embedded within three forms of activity (training form (TF), playing form (PF) and competitive match) and seven sub-activity types. In contrast to traditional drill-based coaching, 58.5% of the training time was found to have been spent in PF activities. Moreover, the proportion of PF activities increased to a peak average of 83.8% in proximity to the team’s annual international championship. Uniquely, one of the coach’s most prolific behaviours was conferring with associates (23.3%), highlighting the importance of interactions with assistant coaches, medical staff and others in shaping the coaching process. Additionally, the frequencies of key behaviours such as questioning and praise were found to vary between the different activity forms and types, raising questions about previous conceptions of effective coaching practice. The findings are discussed in the light of the Game Sense philosophy and the role of the head coach.     

Movement and physiological match demands of elite rugby league using portable global positioning systems

Twelve elite players from an English Super League club consented to participate in the present study using portable global positioning system (GPS) devices to assess position-specific demands. Distances covered at low-intensity running, moderate-intensity running, high-intensity running, very high-intensity running, and total distance were significantly (P < 0.05) lower in forwards compared with outside backs and adjustables. Metres per minute was higher in adjustables and forwards, owing to higher values for relative distance in medium-intensity running and a rise in high-intensity running from previous absolute values. Sprint distance, sprint frequency, and peak speed were higher in outside backs than both adjustables and forwards. A moderate, significant correlation (r = 0.62, P = 0.001) was apparent between session ratings of perceived exertion and summated heart rate. Results support the requirement for position-specific conditioning and provide preliminary evidence for the use of session ratings of perceived exertion as a measure of match load.     

The development of position-specific performance indicators in professional rugby union

The aim of this study was to construct a valid and reliable methodology for the analysis of performance profiles of individual playing positions within rugby union. Twenty-two matches were sampled from the domestic season of a professional male rugby union team. Key performance indicators for individual positions were developed and notated using a computerized behavioural analysis system. Performance profiles of playing positions containing data from one or more individuals were then constructed to compare intra-positional differences. Significant differences (chi-square) were observed between individuals within all the tested playing positions for the principal performance indicators (passing, carrying and tackling for the forward positions, and passing, carrying, tackling and kicking for the backs). For example, the difference between the two outside-halves in the study (P < 0.001) was illustrated by one of the players having a median of 6 successful carries for the season (95% confidence limits of 13 and 3), whereas the other had a median of 2 successful carries (95% confidence limits of 5 and 1). The findings suggest that while general positional performance profiles appear to exist, intra-positional differences may occur due to variations in an individual's style of play, the decision-making demands of the position and the effects of potential confounding variables. Multiple profiles may therefore be necessary for some playing positions to account for variation in factors such as playing conditions and the strength of the opposition.     

The development of position-specific performance indicators in professional rugby union

The aim of this study was to construct a valid and reliable methodology for the analysis of performance profiles of individual playing positions within rugby union. Twenty-two matches were sampled from the domestic season of a professional male rugby union team. Key performance indicators for individual positions were developed and notated using a computerized behavioural analysis system. Performance profiles of playing positions containing data from one or more individuals were then constructed to compare intra-positional differences. Significant differences (chi-square) were observed between individuals within all the tested playing positions for the principal performance indicators (passing, carrying and tackling for the forward positions, and passing, carrying, tackling and kicking for the backs). For example, the difference between the two outside-halves in the study (P?<?0.001) was illustrated by one of the players having a median of 6 successful carries for the season (95% confidence limits of 13 and 3), whereas the other had a median of 2 successful carries (95% confidence limits of 5 and 1). The findings suggest that while general positional performance profiles appear to exist, intra-positional differences may occur due to variations in an individual's style of play, the decision-making demands of the position and the effects of potential confounding variables. Multiple profiles may therefore be necessary for some playing positions to account for variation in factors such as playing conditions and the strength of the opposition.     

Rehabilitation and nutrition protocols for optimising return to play from traditional ACL reconstruction in elite rugby union players: A case study

Current nutrition and exercise focus during rehabilitation periods has been on reducing muscle atrophy associated with immobilisation. This case report outlines a best practice anterior cruciate ligament (ACL) rehabilitation programme undertaken by two professional rugby athletes, with the addition of an evidence-based supplementation (gelatine and vitamin C) and exercise protocol focused on collagenous tissue. Both players ruptured their left ACL and were repaired with a traditional hamstring graft. Players undertook a structured rehabilitation programme for 34 weeks before being clinically assessed ready to play. Players saw minimal changes in body composition in the early rehabilitation period (P1 – 0.8 kg; P2 – 0.4 kg). Leg lean mass reduced in both legs of Player 1 (Injured – 0.8 kg, Non-injured – 0.6 kg) at 17 weeks, with Player 2 only experiencing a loss of 0.3 kg of lean tissue in the injured leg. Both players returned to baseline body compositions after 24 weeks. Leg strength returned to a maximum at 24 and 15 weeks, respectively, with knee function returning to baseline by 30 weeks. This case report provides evidence that nutrition and rehabilitation programmes targeted at minimising the effects of disuse in both muscle and connective tissue may assist return to play after ACL injury.     

Quantitative assessment of developmental levels in overarm throwing using wearable inertial sensing technology

Motor proficiency in childhood has been recently recognised as a public health determinant, having a potential impact on the physical activity level and possible sedentary behaviour of the child later in life. Among fundamental motor skills, ballistic skills assessment based on in-field quantitative observations is progressively needed in the motor development community. The aim of this study was to propose an in-field quantitative approach to identify different developmental levels in overarm throwing. Fifty-eight children aged 5–10 years performed an overarm throwing task while wearing three inertial sensors located at the wrist, trunk and pelvis level and were then categorised using a developmental sequence of overarm throwing. A set of biomechanical parameters were defined and analysed using multivariate statistics to evaluate whether they can be used as developmental indicators. Trunk and pelvis angular velocities and time durations before the ball release showed increasing/decreasing trends with increasing developmental level. Significant differences between developmental level pairs were observed for selected biomechanical parameters. The results support the suitability and feasibility of objective developmental measures in ecological learning contexts, suggesting their potential supportiveness to motor learning experiences in educational and youth sports training settings.     

Technical determinants of tackle and ruck performance in International rugby union

The most frequently occurring contact events in rugby union are the tackle and ruck. The ability repeatedly to engage and win the tackle and ruck has been associated with team success. To win the tackle and ruck, players have to perform specific techniques. These techniques have not been studied at the highest level of rugby union. Therefore, the purpose of this study was to identify technical determinants of tackle and ruck performance at the highest level of rugby union. A total of 4479 tackle and 2914 ruck events were coded for the Six Nations and Championship competitions. Relative risk ratio (RR), the ratio of the probability of an outcome occurring when a characteristic was observed (versus the non-observed characteristic), was determined using multinomial logistic regression. Executing front-on tackles reduced the likelihood of offloads and tackle breaks in both competitions (Six Nations RR 3.0 Behind tackle, 95% confidence interval [95% CI]: 1.9–4.6, effect size [ES] = large, P < 0.001); Championship RR 2.9 Jersey tackle, 95% CI: 1.3–6.4, ES = moderate, P = 0.01). Fending during contact increased the chances of offloading and breaking the tackle in both competitions (Six Nations RR 4.5 Strong, 95% CI: 2.2–9.2, ES = large, P = P < 0.001; Championship RR 5.1 Moderate, 95% CI: 3.5–7.4, ES = large, P < 0.001). For the ruck, actively placing the ball increased the probability of maintaining possession (Six Nations RR 2.2, 95% CI: 1.1–4.3, ES = moderate, P = 0.03); Championship RR 4.0, 95% CI: 1.3–11.8, ES = large, P = 0.01). The techniques identified in this study should be incorporated and emphasised during training to prepare players for competition. Furthermore, these techniques need to be added to coaching manuals for the tackle and ruck.     

Coupling tendencies during exploratory behaviours of competing players in rugby union dyads

This study investigated interpersonal coordination tendencies in 1vs.1 dyads in rugby union, here expressed by participants' movement velocity towards or away from the sideline as they competed to score or prevent a try. We examined whether coupling tendencies of members of each dyad shaped key performance outcomes (try or successful tackle). Data on movement displacement trajectories of eight male rugby union players (aged 11–12 years) were analysed during performance in 47 trials. To assess coordination tendencies during exploratory behaviours in the dyads, analyses of performance time series data were undertaken using variable time graphs, running correlations and cross-correlations. Results revealed distinct coupling patterns characterised by shifts between synchronous coordination and asynchronous coordination tendencies and uncoordinated actions. Observed behaviours were interpreted as attempts of competing participants to create and perceive possibilities for action while seeking to achieve specific performance goals. Findings also revealed that a variety of patterned relations between participants resulted in different performance outcomes.