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Concept: Rugby league

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The 2017 Berlin Concussion in Sport Group Consensus Statement provides a global summary of best practice in concussion prevention, diagnosis and management, underpinned by systematic reviews and expert consensus. Due to their different settings and rules, individual sports need to adapt concussion guidelines according to their specific regulatory environment. At the same time, consistent application of the Berlin Consensus Statement’s themes across sporting codes is likely to facilitate superior and uniform diagnosis and management, improve concussion education and highlight collaborative research opportunities. This document summarises the approaches discussed by medical representatives from the governing bodies of 10 different contact and collision sports in Dublin, Ireland in July 2017. Those sports are: American football, Australian football, basketball, cricket, equestrian sports, football/soccer, ice hockey, rugby league, rugby union and skiing. This document had been endorsed by 11 sport governing bodies/national federations at the time of being published.

Concepts: United States, American football, Rugby union, Football, Rugby league, Team sports, Rugby football, Tag Rugby

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BACKGROUND AND AIM: Strength and power are crucial components to excelling in all contact sports; and understanding how a player’s strength and power levels fluctuate in response to various resistance training loads is of great interest, as it will inevitably dictate the loading parameters throughout a competitive season. This is a systematic review of training, maintenance and detraining studies, focusing on the development, retention and decay rates of strength and power measures in elite rugby union, rugby league and American football players. SEARCH STRATEGIES: A literature search using MEDLINE, EBSCO Host, Google Scholar, IngentaConnect, Ovid LWW, ProQuest Central, ScienceDirect Journals, SPORTDiscus™ and Wiley InterScience was conducted. References were also identified from other review articles and relevant textbooks. From 300 articles, 27 met the inclusion criteria and were retained for further analysis. STUDY QUALITY: Study quality was assessed via a modified 20-point scale created to evaluate research conducted in athletic-based training environments. The mean ± standard deviation (SD) quality rating of the included studies was 16.2 ± 1.9; the rating system revealed that the quality of future studies can be improved by randomly allocating subjects to training groups, providing greater description and detail of the interventions, and including control groups where possible. DATA ANALYSIS: Percent change, effect size (ES = [Post-Xmean - Pre-Xmean)/Pre-SD) calculations and SDs were used to assess the magnitude and spread of strength and power changes in the included studies. The studies were grouped according to (1) mean intensity relative volume (IRV = sets × repetitions × intensity; (2) weekly training frequency per muscle group; and (3) detraining duration. IRV is the product of the number of sets, repetitions and intensity performed during a training set and session. The effects of weekly training frequencies were assessed by normalizing the percent change values to represent the weekly changes in strength and power. During the IRV analysis, the percent change values were normalized to represent the percent change per training session. The long-term periodized training effects (12, 24 and 48 months) on strength and power were also investigated. RESULTS: Across the 27 studies (n = 1,015), 234 percent change and 230 ES calculations were performed. IRVs of 11-30 (i.e. 3-6 sets of 4-10 repetitions at 74-88 % one-repetition maximum [1RM]) elicited strength and power increases of 0.42 % and 0.07 % per training session, respectively. The following weekly strength changes were observed for two, three and four training sessions per muscle region/week: 0.9 %, 1.8 % and 1.3 %, respectively. Similarly, the weekly power changes for two, three and four training sessions per muscle group/week were 0.1 %, 0.3 % and 0.7 %, respectively. Mean decreases of 14.5 % (ES = -0.64) and 0.4 (ES = -0.10) were observed in strength and power across mean detraining periods of 7.2 ± 5.8 and 7.6 ± 5.1 weeks, respectively. The long-term training studies found strength increases of 7.1 ± 1.0 % (ES = 0.55), 8.5 ± 3.3 % (ES = 0.81) and 12.5 ± 6.8 % (ES = 1.39) over 12, 24 and 48 months, respectively; they also found power increases of 14.6 % (ES = 1.30) and 12.2 % (ES = 1.06) at 24 and 48 months. CONCLUSION: Based on current findings, training frequencies of two to four resistance training sessions per muscle group/week can be prescribed to develop upper and lower body strength and power. IRVs ranging from 11 to 30 (i.e. 3-6 sets of 4-10 repetitions of 70-88 % 1RM) can be prescribed in a periodized manner to retain power and develop strength in the upper and lower body. Strength levels can be maintained for up to 3 weeks of detraining, but decay rates will increase thereafter (i.e. 5-16 weeks). The effect of explosive-ballistic training and detraining on pure power development and decay in elite rugby and American football players remain inconclusive. The long-term effects of periodized resistance training programmes on strength and power seem to follow the law of diminishing returns, as training exposure increases beyond 12-24 months, adaptation rates are reduced.

Concepts: Effect size, Meta-analysis, American football, Rugby union, Football, Rugby league, Rugby football, Tag Rugby

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The present study examined the effects of 24 h travel west across 11 time-zones on subjective jet-lag and wellness responses, together with self-reported sleep and upper respiratory symptoms in eighteen professional rugby league players. Measures were obtained one or two days prior to (Pre), and two, six and eight days following travel (Post 2, 6 and 8) from Australia to the United Kingdom for the 2015 World Club Series. Compared to Pre, subjective jet-lag remained significantly elevated on Post 8 (3.1 ± 2.3); p<0.05, d>0.90), though was greatest on Post 2 (4.1 ± 1.4). Self-reported sleep onset times were significantly earlier on Post 2 compared to all other time points (p<0.05, d>0.90) and large effect sizes suggested wake times were earlier on Post 2 compared to Post 6 and 8 (d>0.90). While significantly more upper respiratory symptoms were reported on Post 6 compared to Pre (p<0.05, d>0.90), no incidence of injury and negligible changes in wellness and muscle strength and range of motion (p>0.05, d<0.90) were evident following travel. Results suggest that westward long-haul travel between Australia and the United Kingdom exacerbates subjective jet-lag and sleep responses, along with upper respiratory symptoms in professional rugby league players. Of note, the increase in self-reported upper respiratory symptoms is a reminder that the demands of long-haul travel may be an additional concern to jet-lag for travelling athletes. However, due to the lack of sport-specific performance measures, it is still unclear whether international travel interferes with training to the extent that subsequent competition performance is impaired.

Concepts: United Kingdom, Respiratory system, England, Travel, Football, Rugby league, Rugby football, Rugby League World Cup

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This study investigated the influence of repeated high-intensity effort exercise on tackling ability in rugby league players, and determined the relationship between physical qualities and tackling ability under fatigued conditions in these athletes. Eleven semi-professional rugby league players underwent measurements of speed (10 m and 40 m sprint), upper-body strength (4 repetition maximum [RM] bench press and weighted chin-up), upper-body muscular endurance (body mass maximum repetition chin-up, body mass maximum repetition dips), lower-body strength (4RM squat), and estimated maximal aerobic power (multi-stage fitness test). Tackling ability was assessed using a standardized one-on-one tackling test, before, during, and following four bouts of repeated high-intensity effort (RHIE) exercise. The relationship between physical qualities and fatigue-induced decrements in tackling ability were determined using Pearson product moment correlation coefficients. Each cycle of the RHIE protocol induced progressive reductions in tackling ability. A moderate reduction (Effect Size = ~-1.17 ± 0.60, -34.1 ± 24.3%) in tackling ability occurred after the fourth cycle of the RHIE protocol. Players with greater relative lower-body strength (i.e. 4RM squat/kg) had the best tackling ability under fatigued conditions (r = 0.72, p = 0.013). There were no significant relationships between tackling ability under fatigued conditions and any other physical quality. These findings suggest that lower-body strength protects against fatigue-induced decrements in tackling ability. The development of lower-body strength should be a priority to facilitate the development of robust tackling skills that are maintained under fatigue.

Concepts: Exercise, Mass, Strength training, Weight training, Pearson product-moment correlation coefficient, Karl Pearson, Exercise physiology, Rugby league

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Whole body cryotherapy (WBC) is the therapeutic application of extreme cold air for a short duration. Minimal evidence is available for determining optimal exposure time.

Concepts: Common cold, Duration, Shutter speed, Rugby league

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Prediction of adult performance from early age talent identification in sport remains difficult. Talent identification research has generally been performed using univariate analysis, which ignores multivariate relationships. To address this issue, this study used a novel higher-dimensional model to orthogonalize multivariate anthropometric and fitness data from junior rugby league players, with the aim of differentiating future career attainment. Anthropometric and fitness data from 257 Under-15 rugby league players was collected. Players were grouped retrospectively according to their future career attainment (i.e., amateur, academy, professional). Players were blindly and randomly divided into an exploratory (n = 165) and validation dataset (n = 92). The exploratory dataset was used to develop and optimize a novel higher-dimensional model, which combined singular value decomposition (SVD) with receiver operating characteristic analysis. Once optimized, the model was tested using the validation dataset. SVD analysis revealed 60 m sprint and agility 505 performance were the most influential characteristics in distinguishing future professional players from amateur and academy players. The exploratory dataset model was able to distinguish between future amateur and professional players with a high degree of accuracy (sensitivity = 85.7%, specificity = 71.1%; p<0.001), although it could not distinguish between future professional and academy players. The validation dataset model was able to distinguish future professionals from the rest with reasonable accuracy (sensitivity = 83.3%, specificity = 63.8%; p = 0.003). Through the use of SVD analysis it was possible to objectively identify criteria to distinguish future career attainment with a sensitivity over 80% using anthropometric and fitness data alone. As such, this suggests that SVD analysis may be a useful analysis tool for research and practice within talent identification.

Concepts: Binary classification, Singular value decomposition, Identification, Univariate, Matrix, Rugby league, Singular value

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Repeated sprint ability (RSA) is a critical success factor for intermittent sport performance. Repeated sprint training has been shown to improve RSA, we hypothesised that hypoxia would augment these training adaptations. Thirty male well-trained academy rugby union and rugby league players (18.4±1.5 years, 1.83±0.07 m, 88.1±8.9 kg) participated in this single-blind repeated sprint training study. Participants completed 12 sessions of repeated sprint training (10×6 s, 30 s recovery) over 4 weeks in either hypoxia (13% FiO2) or normoxia (21% FiO2). Pretraining and post-training, participants completed sports specific endurance and sprint field tests and a 10×6 s RSA test on a non-motorised treadmill while measuring speed, heart rate, capillary blood lactate, muscle and cerebral deoxygenation and respiratory measures. Yo-Yo Intermittent Recovery Level 1 test performance improved after RS training in both groups, but gains were significantly greater in the hypoxic (33±12%) than the normoxic group (14±10%, p<0.05). During the 10×6 s RS test there was a tendency for greater increases in oxygen consumption in the hypoxic group (hypoxic 6.9±9%, normoxic (-0.3±8.8%, p=0.06) and reductions in cerebral deoxygenation (% changes for both groups, p=0.09) after hypoxic than normoxic training. Twelve RS training sessions in hypoxia resulted in twofold greater improvements in capacity to perform repeated aerobic high intensity workout than an equivalent normoxic training. Performance gains are evident in the short term (4 weeks), a period similar to a preseason training block.

Concepts: Better, Improve, Capillary, Hypoxia, Rugby league, Rugby football, Tag Rugby

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Exposure to alcohol advertising is associated with greater alcohol consumption in children and adolescents, and alcohol advertising is common in Australian sport. We examine child, adolescent and young adult exposure to alcohol advertising during three televised sports in Australia: Australian Football League (AFL), cricket and the National Rugby League (NRL).

Concepts: Australia, Football, Melbourne, Rugby league, National Rugby League, Australian Football League, Brisbane, Melbourne Cricket Ground

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To investigate the alcohol, gambling, and unhealthy food marketing strategies during a nationally televised, free to air, sporting series in Australia.Methods/approach: Using the Australian National Rugby League 2012 State of Origin three-game series, we conducted a mixed methods content analysis of the frequency, duration, placement and content of advertising strategies, comparing these strategies both within and across the three games.

Concepts: Marketing, New South Wales, Rugby league, National Rugby League, Brisbane, Super League war, New South Wales Rugby League, Rugby League State of Origin

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We investigated (1) the relationship between Type D personality, stress intensity appraisal of a self-selected stressor, coping, and perceived coping effectiveness and (2) the relationship between Type D personality and performance. In study one, 482 athletes completed the Type D personality questionnaire (DS14), stress thermometer and MCOPE in relation to a recently experienced sport stressor. Type D was associated with increased levels of perceived stress and selection of coping strategies (more emotion and avoidance coping) as well as perceptions of their effectiveness. In study two, 32 participants completed a rugby league circuit task and were assessed on pre-performance anxiety, post-performance affect and coping. Type D was associated with poorer performance (reduced distance; more errors), decreases in pre-performance self-confidence and more use of maladaptive resignation/withdrawal coping. Findings suggest that Type D is associated with maladaptive coping and reduced performance. Type D individuals would benefit from interventions related to mood modification or enhancing interpersonal functioning.

Concepts: Psychology, Perception, Concepts in metaphysics, Interpersonal relationship, Emotion, Richard Lazarus, Rugby league, Rugby football