Head Acceleration Events During Tackle, Ball-Carry, and Ruck Events in Professional Southern Hemisphere Men's Rugby Union Matches: A Study Using Instrumented Mouthguards.

OBJECTIVES: Describe head acceleration events (HAEs) experienced by professional male rugby union players during tackle, ball-carry, and ruck events using instrumented mouthguards (iMGs). DESIGN: Prospective observational cohort. METHODS: Players competing in the 2023 Currie Cup (141 players) and Super Rugby (66 players) seasons wore iMGs. The iMG-recorded peak linear acceleration (PLA) and peak angular acceleration (PAA) were used as in vivo HAE approximations and linked to contact-event data captured using video analysis. Using the maximum PLA and PAA per contact event (HAEmax), ordinal mixed-effects regression models estimated the probabilities of HAEmax magnitude ranges occurring, while accounting for the multilevel data structure. RESULTS: As HAEmax magnitude increased the probability of occurrence decreased. The probability of a HAEmax ≥15g was 0.461 (0.435-0.488) (approximately 1 in every 2) and ≥45g was 0.031 (0.025-0.037) (1 in every 32) during ball carries. The probability of a HAEmax >15g was 0.381 (0.360-0.404) (1 in every 3) and >45g 0.019 (0.015-0.023) (1 in every 53) during tackles. The probability of higher magnitude HAEmax occurring was greatest during ball carries, followed by tackles, defensive rucks and attacking rucks, with some ruck types having similar profiles to tackles and ball carries. No clear differences between positions were observed. CONCLUSION: Higher magnitude HAEmax were relatively infrequent in professional men's rugby union players. Contact events appear different, but no differences were found between positions. The occurrence of HAEmax was associated with roles players performed within contact events, not their actual playing position. Defending rucks may warrant greater consideration in injury prevention research.

Training and Match-Related Head Acceleration Events in Top Level Domestic Senior Women's and Men's Rugby Union: A Multi-League Instrumented Mouthguard Study.

The aim of this study was to investigate the difference in head acceleration event (HAE) incidence between training and match-play in women's and men's players competing at the highest level of domestic rugby union globally. Players from Women's (Premiership Women's Rugby, Farah Palmer Cup) and Men's (Premiership Rugby, Currie Cup) rugby union competitions wore instrumented mouthguards during matches and training sessions during the 2022/2023 seasons. Peak linear (PLA) and angular (PAA) acceleration were calculated from each HAE and included within generalized linear mixed-effects models. The incidence of HAEs was significantly greater in match-play compared to training for all magnitude thresholds in both forwards and backs, despite players spending approximately 1.75-2.5 times more time in training. For all HAEs (PLA > 5 g and PAA > 400 rad/s2), incidence rate ratios (IRRs) for match versus training ranged from 2.80 (95% CI: 2.38-3.30; men's forwards) to 4.00 (3.31-4.84; women's forwards). At higher magnitude thresholds (PLA > 25 g; PAA > 2000 rad/s2), IRRs ranged from 3.64 (2.02-6.55; PAA > 2000 rad/s2 in men's backs) to 11.70 (6.50-21.08; PAA > 2000 rad/s2 in women's forwards). Similar trends were observed in each competition. Players experienced significantly more HAEs during match-play than training, particularly at higher magnitude thresholds. Where feasible, HAE mitigation strategies may have more scope for HAE reduction if targeted at match-play, particularly where higher magnitude HAEs are the primary concern. However, the number of HAEs associated with different training drills requires exploration to understand if HAEs can be reduced in training, alongside optimizing match performance (e.g., enhancing contact technique).

Unique diagnostic signatures of concussion in the saliva of male athletes: the Study of Concussion in Rugby Union through MicroRNAs (SCRUM).

OBJECTIVE: To investigate the role of salivary small non-coding RNAs (sncRNAs) in the diagnosis of sport-related concussion. METHODS: Saliva was obtained from male professional players in the top two tiers of England's elite rugby union competition across two seasons (2017-2019). Samples were collected preseason from 1028 players, and during standardised head injury assessments (HIAs) at three time points (in-game, post-game, and 36-48 hours post-game) from 156 of these. Samples were also collected from controls (102 uninjured players and 66 players sustaining a musculoskeletal injury). Diagnostic sncRNAs were identified with next generation sequencing and validated using quantitative PCR in 702 samples. A predictive logistic regression model was built on 2017-2018 data (training dataset) and prospectively validated the following season (test dataset). RESULTS: The HIA process confirmed concussion in 106 players (HIA+) and excluded this in 50 (HIA-). 32 sncRNAs were significantly differentially expressed across these two groups, with let-7f-5p showing the highest area under the curve (AUC) at 36-48 hours. Additionally, a combined panel of 14 sncRNAs (let-7a-5p, miR-143-3p, miR-103a-3p, miR-34b-3p, RNU6-7, RNU6-45, Snora57, snoU13.120, tRNA18Arg-CCT, U6-168, U6-428, U6-1249, Uco22cjg1,YRNA_255) could differentiate concussed subjects from all other groups, including players who were HIA- and controls, immediately after the game (AUC 0.91, 95% CI 0.81 to 1) and 36-48 hours later (AUC 0.94, 95% CI 0.86 to 1). When prospectively tested, the panel confirmed high predictive accuracy (AUC 0.96, 95% CI 0.92 to 1 post-game and AUC 0.93, 95% CI 0.86 to 1 at 36-48 hours). CONCLUSIONS: SCRUM, a large prospective observational study of non-invasive concussion biomarkers, has identified unique signatures of concussion in saliva of male athletes diagnosed with concussion.

Consensus on a video analysis framework of descriptors and definitions by the Rugby Union Video Analysis Consensus group.

Using an expert consensus-based approach, a rugby union Video Analysis Consensus (RUVAC) group was formed to develop a framework for video analysis research in rugby union. The aim of the framework is to improve the consistency of video analysis work in rugby union and help enhance the overall quality of future research in the sport. To reach consensus, a systematic review and Delphi method study design was used. After a systematic search of the literature, 17 articles were used to develop the final framework that described and defined key actions and events in rugby union (rugby). Thereafter, a group of researchers and practitioners with experience and expertise in rugby video analysis formed the RUVAC group. Each member of the group examined the framework of descriptors and definitions and rated their level of agreement on a 5-point agreement Likert scale (1: strongly disagree; 2: disagree; 3: neither agree or disagree; 4: agree; 5: strongly agree). The mean rating of agreement on the five-point scale (1: strongly disagree; 5: strongly agree) was 4.6 (4.3-4.9), 4.6 (4.4-4.9), 4.7 (4.5-4.9), 4.8 (4.6-5.0) and 4.8 (4.6-5.0) for the tackle, ruck, scrum, line-out and maul, respectively. The RUVAC group recommends using this consensus as the starting framework when conducting rugby video analysis research. Which variables to use (if not all) depends on the objectives of the study. Furthermore, the intention of this consensus is to help integrate video data with other data (eg, injury surveillance).

International Olympic Committee consensus statement: methods for recording and reporting of epidemiological data on injury and illness in sport 2020 (including STROBE Extension for Sport Injury and Illness Surveillance (STROBE-SIIS)).

Injury and illness surveillance, and epidemiological studies, are fundamental elements of concerted efforts to protect the health of the athlete. To encourage consistency in the definitions and methodology used, and to enable data across studies to be compared, research groups have published 11 sport-specific or setting-specific consensus statements on sports injury (and, eventually, illness) epidemiology to date. Our objective was to further strengthen consistency in data collection, injury definitions and research reporting through an updated set of recommendations for sports injury and illness studies, including a new Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist extension. The IOC invited a working group of international experts to review relevant literature and provide recommendations. The procedure included an open online survey, several stages of text drafting and consultation by working groups and a 3-day consensus meeting in October 2019. This statement includes recommendations for data collection and research reporting covering key components: defining and classifying health problems; severity of health problems; capturing and reporting athlete exposure; expressing risk; burden of health problems; study population characteristics and data collection methods. Based on these, we also developed a new reporting guideline as a STROBE Extension-the STROBE Sports Injury and Illness Surveillance (STROBE-SIIS). The IOC encourages ongoing in- and out-of-competition surveillance programmes and studies to describe injury and illness trends and patterns, understand their causes and develop measures to protect the health of the athlete. Implementation of the methods outlined in this statement will advance consistency in data collection and research reporting.

When to Pull the Trigger: Conceptual Considerations for Approximating Head Acceleration Events Using Instrumented Mouthguards.

Head acceleration events (HAEs) are acceleration responses of the head following external short-duration collisions. The potential risk of brain injury from a single high-magnitude HAE or repeated occurrences makes them a significant concern in sport. Instrumented mouthguards (iMGs) can approximate HAEs. The distinction between sensor acceleration events, the iMG datum for approximating HAEs and HAEs themselves, which have been defined as the in vivo event, is made to highlight limitations of approximating HAEs using iMGs. This article explores the technical limitations of iMGs that constrain the approximation of HAEs and discusses important conceptual considerations for stakeholders interpreting iMG data. The approximation of HAEs by sensor acceleration events is constrained by false positives and false negatives. False positives occur when a sensor acceleration event is recorded despite no (in vivo) HAE occurring, while false negatives occur when a sensor acceleration event is not recorded after an (in vivo) HAE has occurred. Various mechanisms contribute to false positives and false negatives. Video verification and post-processing algorithms offer effective means for eradicating most false positives, but mitigation for false negatives is less comprehensive. Consequently, current iMG research is likely to underestimate HAE exposures, especially at lower magnitudes. Future research should aim to mitigate false negatives, while current iMG datasets should be interpreted with consideration for false negatives when inferring athlete HAE exposure.

Embracing the impact from instrumented mouthguards (iMGs): A survey of iMG managers' perceptions of staff and player interest into the technology, data and barriers to use.

Instrumented mouthguards (iMGs) are a novel technology being used within rugby to quantify head acceleration events. Understanding practitioners' perceptions of the barriers and facilitators to their use is important to support implementation and adoption. This study assessed men's and women's rugby union and league iMG managers' perceptions of staff and player interest in the technology, data and barriers to use. Forty-six iMG managers (men's rugby union and league n = 20 and n = 9 and women's rugby union and league n = 7 and n = 10) completed an 18-question survey. Perceived interest in data varied across staff roles with medical staff being reported as having the most interest. The iMG devices were perceived as easy to use but uncomfortable. Several uses of data were identified, including medical applications, player monitoring and player welfare. The comfort, size and fit of the iMG were reported as the major barriers to player use. Time constraints and a lack of understanding of data were barriers to engagement with the data. Continued education on how iMG data can be used is required to increase player and staff buy-in, alongside improving comfort of the devices. Studies undertaken with iMGs investigating player performance and welfare outcomes will make data more useful and increase engagement.

The Incidence and Propensity of Head Acceleration Events in a Season of Men's and Women's English Elite-Level Club Rugby Union Matches.

OBJECTIVES: To describe and compare the incidence and propensity of head acceleration events (HAEs) using instrumented mouthguards (iMG) by playing position in a season of English elite-level men's and women's rugby union matches. METHODS: iMG data were collected for 255 men and 133 women from 1,865 and 807 player-matches, respectively, and synchronised to video-coded match footage. Head peak resultant linear acceleration (PLA) and peak resultant angular acceleration (PAA) were extracted from each HAE. Mean incidence and propensity values were calculated across different recording thresholds for forwards and backs in addition to positional groups (front row, second row, back row, half backs, centres, back three) with 95% confidence intervals (CI) estimated. Significance was determined based on 95% CI not overlapping across recording thresholds. RESULTS: For both men and women, HAE incidence was twice as high for forwards than backs across the majority of recording thresholds. HAE incidence and propensity were significantly lower in the women's game compared to the men's game. Back-row and front-row players had the highest incidence across all HAE thresholds for men's forwards, while women's forward positional groups and men's and women's back positional groups were similar. Tackles and carries exhibited a greater propensity to result in HAE for forward positional groups and the back three in the men's game, and back row in the women's game. CONCLUSION: These data offer valuable benchmark and comparative data for future research, HAE mitigation strategies, and management of HAE exposure in elite rugby players. Positional-specific differences in HAE incidence and propensity should be considered in future mitigation strategies.

Measurement of steroid hormones in saliva: Effects of sample storage condition.

Measurement of steroid hormones in saliva is increasingly common in elite sport settings. However, this environment may enforce handling and storage practices that introduce error in measurement of hormone concentrations. We assessed the influence of storage temperature and duration on reproducibility of salivary steroid levels. Nine healthy adults provided morning and afternoon saliva samples on two separate occasions. Each sample was divided into identical saliva aliquots which were stored long-term (i.e. 28 and 84 days) at - 80°C or - 20°C (testing day 1), and short-term (i.e. 1, 3, 7 and 14 days) at 4°C or 20°C (testing day 2). Samples were analyzed for cortisol, testosterone and estradiol using ELISA. In non-freezer conditions, there was a decrease from baseline to 7 days in testosterone (- 26 ± 15%) and estradiol (- 58 ± 17%) but not cortisol concentrations (p < 0.001). This decrease was larger in samples stored at room temperature than in the refrigerator (p ≤ 0.01). There were small but significant changes in measured concentrations of all hormones after 28 and/or 84 days of storage in freezer conditions (p ≤ 0.01), but these were generally within 12% of baseline concentrations, and may be partly explained by inter-assay variability. Whole saliva samples to be analyzed for cortisol, testosterone and estradiol should be frozen at - 20°C or below within 24 h of collection, and analyzed within 28 days. Storage of samples for measurement of testosterone and estradiol at temperatures above - 20°C can introduce large error variance to measured concentrations.

Quantifying head acceleration exposure via instrumented mouthguards (iMG): a validity and feasibility study protocol to inform iMG suitability for the TaCKLE project.

Instrumented mouthguards (iMGs) have the potential to quantify head acceleration exposures in sport. The Rugby Football League is looking to deploy iMGs to quantify head acceleration exposures as part of the Tackle and Contact Kinematics, Loads and Exposure (TaCKLE) project. iMGs and associated software platforms are novel, thus limited validation studies exist. The aim of this paper is to describe the methods that will determine the validity (ie, laboratory validation of kinematic measures and on-field validity) and feasibility (ie, player comfort and wearability and practitioner considerations) of available iMGs for quantifying head acceleration events in rugby league. Phase 1 will determine the reliability and validity of iMG kinematic measures (peak linear acceleration, peak rotational velocity, peak rotational acceleration), based on laboratory criterion standards. Players will have three-dimensional dental scans and be provided with available iMGs for phase 2 and phase 3. Phase 2 will determine the on-field validity of iMGs (ie, identifying true positive head acceleration events during a match). Phase 3 will evaluate player perceptions of fit (too loose, too tight, bulky, small/thin, held mouth open, held teeth apart, pain in jaw muscles, uneven bite), comfort (on lips, gum, tongue, teeth) and function (speech, swallowing, dry mouth). Phase 4 will evaluate the practical feasibility of iMGs, as determined by practitioners using the system usability scale (preparing iMG system and managing iMG data). The outcome will provide a systematic and robust assessment of a range of iMGs, which will help inform the suitability of each iMG system for the TaCKLE project.

Study of Concussion in Rugby Union through MicroRNAs (SCRUM): a study protocol of a prospective, observational cohort study.

INTRODUCTION: The diagnosis of mild traumatic brain injury or sports-related concussion is a challenge for all clinicians, players, coaches and parents involved in contact sports. Currently, there is no validated objective biomarker available to assess the presence or severity of concussion in sport, and so it is necessary to rely on subjective measures like self-reporting of symptoms which depend on the cooperation of the athlete. There is a significant health risk associated with repetitive injury if the diagnosis is missed, and so there is great value in an objective biomarker to assist diagnostic and prognostic decisions. OBJECTIVE: To establish a panel of non-invasive MicroRNA biomarkers in urine and saliva for the rapid diagnosis of sports-related concussion and investigate the kinetics and clinical utility of these biomarkers in assisting diagnostic, prognostic and return-to-play decisions. METHODS AND ANALYSIS: Observational, prospective, multicentre cohort study recruiting between the 2017-2018 and 2018-2019 Rugby Union seasons. Professional rugby players in the two highest tiers of senior professional domestic rugby competition in England will be recruited prospectively to the study. During the season, three groups will be identified: athletes entering the World Rugby Head Injury Assessment (HIA) protocol, uninjured control athletes and control athletes with musculoskeletal injuries. Saliva and urine will be collected from these athletes at multiple timepoints, coinciding with key times in the HIA protocol and return-to-play process. ETHICS AND DISSEMINATION: Ethics approval has been obtained. The compiled and analysed results will be presented at national and international conferences concerning the care of patients with traumatic brain injury. Results will also be submitted for peer review and publication in the subject journals/literature.

Growth hormone responses to sub-maximal and sprint exercise.

Exercise is a potent stimulus for growth hormone (GH) release and a single bout of exercise can result in marked elevations in circulating GH concentrations. The magnitude of the GH response to exercise will vary according to the type, intensity and duration of exercise as well as factors such as the age, gender, body composition and fitness status of the individual performing the exercise. However, the mechanisms regulating GH release in response to exercise are not fully understood. This review considers the GH responses to sub-maximal and sprint exercise and discusses the factors that might affect GH release along with the mechanisms that have been proposed to regulate exercise-induced GH release.

Relationship between pregame concentrations of free testosterone and outcome in rugby union.

PURPOSE: To assess the measures of salivary free testosterone and cortisol concentrations across selected rugby union matches according to game outcome. METHODS: Twenty-two professional male rugby union players were studied across 6 games (3 wins and 3 losses). Hormone samples were taken 40 min before the game and 15 min after. The hormonal data were grouped and compared against competition outcomes. These competition outcomes included wins and losses and a game-ranked performance score (1-6). RESULTS: Across the entire team, pregame testosterone concentrations were significantly higher during winning games than losses (P = 5.8 × 10-5). Analysis by playing position further revealed that, for the backs, pregame testosterone concentrations (P = 3.6 × 10-5) and the testosterone-to-cortisol ratio T:C (P = .038) were significantly greater before a win than a loss. Game-ranked performance score correlated to the team's pregame testosterone concentrations (r = .81, P = .049). In backs, pregame testosterone (r = .91, P = .011) and T:C (r = .81, P = .05) also correlated to game-ranked performance. Analysis of the forwards' hormone concentrations did not distinguish between game outcomes, nor did it correlate with game-ranked performance. Game venue (home vs away) only affected postgame concentrations of testosterone (P = .018) and cortisol (P = 2.58 × 10-4). CONCLUSIONS: Monitoring game-day concentrations of salivary free testosterone may help identify competitive readiness in rugby union matches. The link between pregame T:C and rugby players in the back position suggests that monitoring weekly training loads and enhancing recovery modalities between games may also assist with favorable performance and outcome in rugby union matches.