Predictors of upper respiratory tract symptom risk: Differences between elite rugby union and league players.

This study examined possible predictors of upper respiratory tract symptom (URTS) episodes in elite rugby union and league players (n = 51) during intensive pre-season training. Baseline saliva and blood samples were collected in the first week of pre-season training for analysis of salivary secretory immunoglobulin A (SIgA) and cytomegalovirus. Thereafter, SIgA, URTS, internal training load and self-reported wellness data were repeatedly measured throughout a 10-week pre-season training period. Univariate frailty model analysis, which included 502 observations, was performed for each rugby code for the following independent predictor variables: SIgA concentration, internal training load, total wellness, sleep quantity, sleep quality and stress. Rugby union and league players experienced a similar number of URTS episodes; however, predictors of URTS episodes differed between the codes. No biomarkers or self-reported measures significantly predicted URTS risk in rugby union players, while reductions in self-reported total wellness (HR: 0.731, p = 0.004) and sleep quality (HR: 0.345, p = 0.001) predicted increased URTS risk in rugby league players. The findings from this study highlight that factors influencing URTS risk are perhaps sport specific and this may be attributed to different sporting demands and/or different management of players by team-practitioners.

Distinct trajectories of athlete development: A retrospective analysis of professional rugby league players.

Contemporary models of athlete development (e.g., Development Model of Sport Participation) suggest attainment benefits from early age multi-sport "sampling" behaviour before progressive transition into "invested" single-sport involvement in teenage years compared to intensive early-age specialisation. However, specific examinations of these development patterns across a number of team sports and cultural contexts remains limited. This study involved a large sample of professional Australian Rugby League (RL) players (N = 224) who progressed along the RL system pathways. It defined two contrasting athlete development trajectories based upon initial entry into formal age group representative teams ("Early": U16, U18; "Later": U20+) to compare their developmental participation patterns using the National Rugby League Athlete Development Questionnaire (NRLADQ). Between-Within Analyses of Variance (BW-ANOVA)'s identified interaction effects as the 'Later' group reported lower volumes of deliberate practice from 10-20 years, RL-game involvement from 10-20 years, deliberate play from 5-12 years, and a later reduction in other sporting involvement. Group differences in RL-related deliberate practice and play were supported by qualitative descriptions of training at age-categories. CONCLUSION: RL professional senior elite success level can be attained via early intensified specialised investment and accelerated youth success as well as by a rather decelerated, much less cost-intensive participation pattern.

Does self-perceived sleep reflect sleep estimated via activity monitors in professional rugby league athletes?

This study examined agreement between self-perceived sleep and sleep estimated via activity monitors in professional rugby league athletes. 63 athletes, from three separate teams wore actigraphy monitors for 10.3 ± 3.9 days. During the monitoring period, ratings of perceived sleep quality (on a 1-5 and 1-10 Likert scale), and an estimate of sleep duration were recorded daily. Agreement between sleep estimated via activity monitors and self-perceived sleep was examined using mean bias, Pearson correlation (r) and typical error of the estimate (TEE). 641 nights of sleep were recorded, with a very large, positive correlation observed between sleep duration estimated via activity monitors and subjective sleep duration (r = 0.85), and a TEE of 48 minutes. Mean bias revealed subjective sleep duration overestimated sleep by an average of 19.8 minutes. The relationship between sleep efficiency estimated via activity monitors and self-perceived sleep quality on a 1-5 (r = 0.22) and 1-10 Likert scale (r = 0.28) was limited. The outcomes of this investigation support the use of subjective measures to monitor sleep duration in rugby league athletes when objective means are unavailable. However, practitioners should be aware of the tendency of athletes to overestimate sleep duration.

The introduction of the six-again rule has increased acceleration intensity across all positions in the National Rugby League competition.

The impact of the six-again rule change on the movement of National Rugby League (NRL) athletes was examined. Player Global Navigation Satellite System (GNSS) data (10 Hz) was collected from 42 athletes who competed in 56 matches across the 2019 to 2021 NRL seasons. Maximal mean speed (m·min-1) and acceleration (m·s-2) were established across a 10 s to 10-min duration via raw GNSS files, with subsequent intercept (mean estimates) and slope values determined via power law analysis. The distributions of match distance (m) and impulse (kN·s-1) were established during ball-in-play time. To determine the significance between positions and seasons under different rules, linear mixed models were used. Effects were described using standardised effect sizes (ES) with 90% confidence limits (CL). Acceleration intercepts (power law-derived) across all positions were substantially greater (>0.6 SD) following the introduction of the six-again rule in the 2020 (mean ± SD; 1.02 ± 0.10 m·s-2) and 2021 seasons (1.05 ± 0.08 m·s-2) compared to the 2019 season (0.91 ± 0.07 m·s-2). Mean acceleration during ball-in-play time was greater in 2020 (ES; 90% CL = 0.75; ± 0.32) compared to 2019. The acceleration requirements of rugby league increased across all positional groups following the modification in NRL competition rules. Practitioners should tailor training programs for athletes to reflect the increased acceleration intensity found under the revised competition format.

Assessing the Ecological-Context Strengths of School-Based Talent Development Programs in Rugby League.

Purpose: Adopting an ecological perspective, the study explored the context-strengths of three successful school-based TDEs in rugby league. Method: Utilizing a mixed methods approach, incorporating validated psychometric questionnaires (N = 118) and semi-structured interviews, various stakeholder perspectives (N = 30; i.e., current/past students and coaches) were triangulated and corroborated to identify TDE ecological strengths. Results: Compared to benchmark TDE data, and supplemented by descriptions of TDE features and processes, results confirmed strong coherence to "effective" factors in TDE literature. Collective "ecological strengths" included quantitative findings of a highly supportive culture, shared "person" and "athlete" desired outcomes, and a long-term focus; and qualitative features of high behavioral expectations, strong values of hard work, and the promotion of personal ownership in athlete development. Opportunities to enhance TDE effectiveness were also identified, with psychological skill development (e.g., self-reflection, coping) and balancing intra-rugby league pathway demands (i.e., competition/training loads) highlighted. Conclusion: Findings identify characteristics, components, and processes of school-TDE environments associated with successful athlete development in schools and beyond (i.e., transition into an athlete development pathway).

Modelling the relationships between volume, intensity and injury-risk in professional rugby league players.

OBJECTIVE: This study aimed to: (a) identify the association between external-workloads and injury-risk in the subsequent week; and (b) understand the effectiveness of workload variables in establishing injury-risk. DESIGN: Retrospective cohort study. METHODS: Workload and injury data (soft-tissue) were collected from forty-eight professional male rugby league players. Load variables included duration (min), total distance (m), relative distance (mmin-1), high speed distance ([m]>20kmh-1), very-high speed distance ([m]>25kmh-1), acceleration and deceleration efforts (count) and PlayerLoad (Arbitrary Unit: AU). Cumulative two-, three- and four-weekly loads; Acute:Chronic Workload Ratio (ACWR); Mean-Standard Deviation Workload Ratio (MSWR) and strain values were calculated and divided into three equally-sized bins (low, moderate and high). Generalised Estimating Equations analysed relationships between workload variables and injury probability in the subsequent week. RESULTS: Injury-risk increased alongside increases in the ACWR for duration, total distance and PlayerLoad. Conversely, injury-risk decreased (Area Under Curve: 0.569-0.585) with increases in the four-weekly duration, total distance, accelerations, decelerations and PlayerLoad. For relative distance, high four-weekly workloads (high: >60mmin-1) demonstrated a positive association with injury-risk, whilst high two-weekly loads (high: >82 mmin-1) were negatively associated. CONCLUSIONS: A range of external workload metrics and summary statistics demonstrate either positive or negative associations with injury-risk status. Such findings provide the framework for the development of decision-support systems in which external workload metrics (e.g. total or high speed distance) can be uniquely and routinely monitored across a range of summary statistics (i.e. cumulative weekly loads and ACWR) in order to optimise player performance and welfare.