Keith A. Stokes

Head acceleration event (HAE) outcomes in elite men's rugby union have been well described during matches and in-season training but have not been investigated during pre-season training. Describe HAE incidence and magnitude during elite men's pre-season rugby union training. Data was collected from three English PREM Rugby clubs (44 training sessions and 53 players) during field-based training sessions using instrumented mouthguards (iMGs) throughout the pre-season training period before the 2025-26 season. Training drills were recorded using routinely tagged GPS data. The incidence of HAEs was calculated per player minute, for forwards and backs, and during training sessions during the first, middle, and final three-week phases of pre-season. A negative binomial generalised linear mixed model compared playing position, and phases of pre-season, expressed as incidence rate ratios (IRR). The magnitude of HAEs were positively skewed. The mean incidence of HAEs ≥ 5 g and ≥ 0.4 krad/s² during a pre-season training session was 0.08/min [95% CI 0.07-0.09] and equated to 5.09 ± 5.12 HAEs per player-training-session exposure. The mean incidence of HAEs ≥ 5 g and ≥ 0.4 krad/s² for forwards was 0.10/min [0.08-0.11] and equated to 5.87 ± 5.51 HAEs per player-training-session exposure, compared to 0.05/min [0.04-0.07] and 3.22 ± 3.39 HAEs per player-training-session exposure for backs (IRR = 1.84 [1.02-3.31], p = 0.041). The mean HAE incidence for forwards during the first three weeks of pre-season was lower (0.05/min [0.03-0.08]) than the middle (0.09/min [0.07-0.11]) and final (0.13/min [0.11-0.15]) three weeks. The incidence of HAEs for backs was similar in the first (0.04/min [0.02-0.06]), middle (0.06/min [0.04-0.08] and final (0.06/min [0.04-0.08]) three weeks. The incidence of HAEs during the middle (IRR = 1.55 [1.14-2.11], p = 0.005) and final (IRR = 2.82 [2.06-3.85], p < 0.001) phases of pre-season was statistically significant. The incidence and magnitude of HAEs during pre-season is very low compared to matches and similar to in-season training. Future work should identify players who accumulate more HAEs in matches and training compared to the rest of the population, and why. This study completes a holistic understanding of HAE exposure throughout a season, which can be used to benchmark individual's exposure against.

Rugby Union is a full contact collision sport, whereby success in the tackle event, is a key marker of match outcome. Moreover, the tackle is associated with the sport's most prevalent injury, concussion. To date, we have little insight into players’ experience of the tackle. Therefore, a series of online focus groups were performed to understand elite male rugby union players’ experiences of collision. Facilitated by a moderator, focus groups were performed with eighteen elite rugby union players across four teams, utilising the Microsoft Teams platform. All players were competing in the Gallagher Premiership during the 2024/ 2025 season. Braun and Clarke's (2019) reflexive thematic analysis was employed. To assist the analysis, Bronfenbrenner′s ecological systems model was applied to illustrate the interlinking systems that influence the tackle event, directly or from afar. Findings generated four key themes: 1) Microsystem – People, Positions and Time Determine the Tackle, 2) Mesosystem – Where Coaching Meets the Process of Tackle Variation, 3) Exosystem – Tackle Contexts in relation to rules, refereeing and the laws of the game, and 4) Macrosystem – Wider Contexts Driving Tackle Experiences. The findings detailed here offer novel insights into the tackle event in elite men's rugby union and an ecological platform for future work.

Objective: To identify characteristics of tackling, of being tackled and interactions between tackle characteristics that are associated with concussion. Methods: A case-control study in male professional rugby union players in England over five seasons (2016/2017 to 2020/2021) analysed characteristics of tackles that led to a clinically diagnosed concussion (cases), and a control group of tackles that did not result in a concussion. ORs were plotted against the overall frequency of each tackle characteristic. Results: 231 tackles resulting in concussions (tackler 178, 77%; ball-carrier 53, 23%), alongside 9963 control tackles, were analysed. For tacklers, ‘head to torso’ ( _{Lower CI} OR _{Upper CI; 4.0} 6.5 _10.7 ) had relatively low odds of concussion compared with ‘no head contact’. ‘Head to knee’ had the highest odds of concussion ( _75.3 155.8 _322.4 ), but ‘head to hip’ occurred more frequently and had the highest number of concussions per 1000 tackles (3.1/1000 tackles). For ball-carriers, ‘head to head’ contact had the highest odds of concussion ( _56.7 104.3 _192.0 ). When ‘tackler body position’ was ‘upright’, the odds of concussion to the tackler were significantly higher when contacting the ball-carrier’s ‘head and neck’ versus their ‘torso’ ( _3.0 23.7 _206.7 ). Conclusions: Lower tackles reduce the chances of concussion to ball-carriers. The influence of tackle height on concussion to tacklers is more nuanced, but the chances are relatively low when contact is made with the ball-carrier’s torso. These findings support ongoing implementation of strategies to reduce concussion risk by lowering tackle height to target the torso.

Objectives: The aim of this study was to describe the incidence and magnitude of head acceleration events (HAEs) during elite men’s and women’s rugby union training for different contact training levels and drill types. Method: Data were collected during the 2022–23 and 2023–24 seasons from 203 men and 125 women from 13 clubs using instrumented mouthguards (iMGs) during in-season training. One author reviewed the training videos to identify the contact level and drill type. HAE incidence was calculated per player minute. Results: For men’s forwards and backs, only 4.7% and 5.8% of HAEs were ≥ 25 g and ≥ 1.5 Krad/s ² , and 3.4% and 4.4% for women’s forwards and backs, respectively. The incidence of ≥ 5 g and ≥ 0.4 Krad/s ² was highest during full-contact training for men’s forwards (0.20/min) and backs (0.16/min) and women’s forwards (0.10/min). HAE incidence was 2–3 times higher during repetition-based compared with game-based training drills for men’s forwards (0.25/min vs 0.09/min) and backs (0.22/min vs 0.09/min) and women’s forwards (0.09/min vs 0.04/min) and backs (0.08/min vs 0.03/min). HAE incidences were halved when repetition-based training drills used pads compared with no pads for men’s forwards (0.21/min vs 0.44/min) and backs (0.17/min vs 0.30/min), and women’s forwards (0.06/min vs 0.14/min) and backs (0.06/min vs 0.10/min). Conclusion: The average HAE incidence (~ 13–20% of weekly HAEs) and magnitude during an in-season training week is very low compared with matches. Opportunities to materially reduce HAE exposure in training are likely more limited than previously assumed. Future research on HAE load and injury, and understanding players’ specific weekly training exposure, may inform effective individual player management.

Objective Within women’s rugby league (n=12 teams), we (1) identified modifiers for head-to-head contacts informed by sport partners (eg, players, coaches, match officials); (2) compared head-to-head contact and concussion rates to the previous two seasons following a one-season tackle technique coaching intervention and (3) explored barriers and enablers of the intervention. Methods A multi-method design was used. Part 1: Mitigation strategies were identified by sport partners reviewing footage of head-to-head contacts, informing the development of a coach-targeted tackle technique intervention. Part 2 evaluated the intervention, comparing head-to-head contact and concussion incidence rates (IRs). Interviews with coaches and players (n=6) explored barriers and enablers to effective implementation and compliance with the intervention. Results Sport partners reported tacklers were more responsible for head-to-head contacts and lowering the tackle height was the most frequently suggested mitigation strategy preintervention and postintervention. Head-to-head contact rates were significantly lower during the intervention than preintervention (IR 59; 95% CI 56 to 62 vs IR 28; 95% CI 25 to 30/1000 tackle events); however, concussion rates showed no difference. Perceived barriers to the intervention included underdeveloped physical and technical foundations of players, lack of knowledge and understanding of the intervention and its purpose, and the environmental context and lack of resources in women’s rugby league. Beliefs about the consequences of the tackle and concussion were perceived as barriers and enablers. Conclusions Head-to-head contact rates were significantly lower; however, concussion rates did not decrease following a tackle technique coaching intervention. Reduced head-to-head contacts are potentially due to an increased focus on head injury reduction and increased player/coach awareness and support.

Background: Data on upper limb injuries in elite female rugby athletes are limited. This study aims to describe the incidence, severity and burden of upper limb injuries over five seasons in elite women’s rugby at both the club and international levels in training and matches. Methods: A longitudinal cohort study was conducted from the 2017/2018 to 2021/2022 seasons, involving female players from the English club top tier and international team. Data on upper limb injuries were reported by team medical staff, capturing injury type, location, severity and mechanism. Injury incidence was calculated per 1000 hours of match/training exposure, and burden was measured by multiplying incidence by severity. Results: A total of 190 upper limb injuries were recorded, with shoulder injuries the most common, representing 43% of all injuries. Median severity (mid-range of injury severity within the data) in international settings was lower than in club settings (Club matches 38 days, IQR 65, international matches 15 days, IQR 55). Injury burden (which is derived from injury mean severity and injury incidence) was significantly higher at international level (club matches, 265 days/1000 hours, 95% CI 213 to 328; club training 6 days/1000 hours, 95% CI 6 to 8; international matches 2638 days/1000 hours, 95% CI 2000 to 3481; international training 51 days/1000 hours, 95% CI 30 to 88). Conclusions: The current study data highlight a low injury severity at an international level. Although the international injury severity rate is higher than club injury incidence and burden. Hand injuries were more common within club training settings, and the shoulder was more prevalent in all other settings.

Background Head-on-head impacts are a risk factor for concussion, which is a concern for sports. Computer vision frameworks may provide an automated process to identify head-on-head impacts, although this has not been applied or evaluated in rugby. Methods This study developed and evaluated a novel computer vision framework to automatically classify head-on-head and non-head-on-head impacts. Tackle events from professional rugby league matches were coded as either head-on-head or non-head-on-head impacts. These included non-televised standard-definition and televised high-definition video clips to train (n=341) and test (n=670) the framework. A computer vision framework consisting of two deep learning networks, an object detection algorithm and three-dimensional Convolutional Neural Networks, was employed and compared with the analyst-coded criterion. Sensitivity, specificity and positive predictive value were reported. Results The overall performance evaluation of the framework to classify head-on-head impacts against manual coding had a sensitivity, specificity and positive predictive value (95% CIs) of 68% (58% to 78%), 84% (78% to 88%) and 0.61 (0.54 to 0.69) in standard-definition clips, and 65% (55% to 75%), 84% (79% to 89%) and 0.61 (0.53 to 0.68) in high-definition clips. Conclusion The study introduces a novel computer vision framework for head-on-head impact detection. Governing bodies may also use the framework in real time, or for retrospective analysis of historical videos, to establish head-on-head rates and evaluate prevention strategies. Future work should explore the application of the framework to other head-contact mechanisms and also the utility in real time to identify potential events for clinical assessment.

Objectives To determine the rates, severity and burden of knee injuries in professional male rugby union from the English Premiership. Methods Injury and exposure data were captured over 20 seasons using a prospective cohort design. Knee injury incidence, days’ absence and burden were recorded for each injury type and by pitch surface type for match and training. Results The rate of knee injury in matches was 9.8/1000 hours (95% CIs 9.3–10.3). Mean days lost were 50 (95% CI 46 to 53) in matches and 51 (95% CI 44 to 57) in training. In matches, medial collateral ligament injuries were the most common, while anterior cruciate ligament (ACL) injuries had the highest mean severity and burden. There was no significant change in the count of knee injuries over time; however, average severity increased significantly (annual change: 2.18 days (95% CI 1.60 to 2.77); pConclusion Knee injuries in matches are common and severe in English professional men’s rugby union. Despite an increased focus on player conditioning and injury prevention throughout the study period, rates of knee injury remained stable, and resulting days’ absence increased. New strategies for the prevention of knee injuries should be considered a priority.