Surveillance is the first step to preventing injury among fast jet aircrew: results of a 2-year prospective cohort study.

OBJECTIVES: Injury surveillance is imperative for injury prevention but difficult in military populations. Our objective was to accurately describe the pattern of musculoskeletal complaints among Royal Australian Air Force (RAAF) fast jet aircrew (FJA) using the validated University of Canberra Fast Jet Aircrew Musculoskeletal Questionnaire (UC-FJAMQ) over a 2-year period, and determine injury burden on the workforce and operational capability. METHODS: 306 RAAF FJA were monitored over a 2-year period (4×5 month reporting periods). Musculoskeletal complaint episodes (MCEs) were captured weekly using the UC-FJAMQ. Time loss episodes (TLEs) were captured from the UC-FJAMQ and injury registers completed by embedded physiotherapists. Cumulative severity and operational impact scores from the UC-FJAMQ, and time loss duration, were used to describe severity and calculate burden. RESULTS: Mean weekly UC-FJAMQ response rate was 62%. 1012 MCEs were captured, with a mean weekly prevalence of 14.9% (95% CI 14.2-15.6), and incidence of 4.1 episodes per person-year (95% CI 3.9-4.4). A total of 145 TLEs were captured, with a mean 5-month prevalence of 12.4% (range 8.9-15.3%), and incidence of 0.37 episodes per person-year (95% CI 0.31-0.43). Spinal regions accounted for 81% of MCEs and contributed 76% and 85% of burden in relation to cumulative severity and operational impact, respectively. 57% of TLE burden came from spinal regions. CONCLUSIONS: Despite modest weekly UC-FJAMQ response rates, musculoskeletal complaints were shown to be widespread and negatively impact operational capability. Future injury prevention efforts among FJA should focus on spinal regions, particularly the neck.

Repeated High-Intensity Effort Activity in International Male Rugby Sevens.

ABSTRACT: Couderc, A, Gabbett, TJ, Piscione, J, Robineau, J, Peeters, A, Igarza, G, Thomas, C, Hanon, C, and Lacome, M. Repeated high-intensity effort activity in international male Rugby Sevens. J Strength Cond Res 35(6): 1720-1726, 2023-Rugby Sevens is characterized by repeated high-intensity accelerations, sprinting, and collisions, commonly referred to as repeated high-intensity effort (RHIE) activity. Although repeated acceleration and sprinting activity of Rugby Sevens has been investigated, to date, no study has investigated the repeated running and collision activity of international Rugby Sevens during competitive events. In this study, 15 elite players competed in 44 matches during the HSBC World Sevens Series. Global positioning systems and match analysis software were used to quantify the frequency of repeated running and collision efforts. High acceleration (≥2.5 m·s -2 ), high speed (above maximal aerobic speed), sprint (above 85% of maximal sprint speed), and collision efforts (tackles, ruck, and contact) were considered as high-intensity effort activities. An RHIE bout was defined as 3 or more high-intensity efforts with less than 21 seconds recovery between efforts. The difference between positional groups (forward and backs) and first and second halves was compared using magnitude-based inferential statistics. One hundred twelve individual match observations were analyzed. On average, players performed 27 high-intensity effort events across the game. The distribution of high-intensity efforts included the following: 37% collisions, 34% accelerations, 27.5% high-velocity running, and 1.5% sprints. An average of 3.7 RHIE bouts was performed per player. The difference in high-intensity efforts and number of RHIE bouts performed were trivial/small when compared between first and second halves, and between forward and back positional groups. Repeated high-intensity effort bouts play an important role in the activity profile of elite Rugby Sevens players. This study could provide a framework for performance analysts and coaches to analyze match-related performance of elite Rugby Sevens players, taking into account both the high-intensity running and collision components of the game. Coaches should implement training interventions to ensure the maintenance of RHIE performance during competitive events.

Wearable Sensor Technology to Predict Core Body Temperature: A Systematic Review.

Heat-related illnesses, which range from heat exhaustion to heatstroke, affect thousands of individuals worldwide every year and are characterized by extreme hyperthermia with the core body temperature (CBT) usually > 40 °C, decline in physical and athletic performance, CNS dysfunction, and, eventually, multiorgan failure. The measurement of CBT has been shown to predict heat-related illness and its severity, but the current measurement methods are not practical for use in high acuity and high motion settings due to their invasive and obstructive nature or excessive costs. Noninvasive predictions of CBT using wearable technology and predictive algorithms offer the potential for continuous CBT monitoring and early intervention to prevent HRI in athletic, military, and intense work environments. Thus far, there has been a lack of peer-reviewed literature assessing the efficacy of wearable devices and predictive analytics to predict CBT to mitigate heat-related illness. This systematic review identified 20 studies representing a total of 25 distinct algorithms to predict the core body temperature using wearable technology. While a high accuracy in prediction was noted, with 17 out of 18 algorithms meeting the clinical validity standards. few algorithms incorporated individual and environmental data into their core body temperature prediction algorithms, despite the known impact of individual health and situational and environmental factors on CBT. Robust machine learning methods offer the ability to develop more accurate, reliable, and personalized CBT prediction algorithms using wearable devices by including additional data on user characteristics, workout intensity, and the surrounding environment. The integration and interoperability of CBT prediction algorithms with existing heat-related illness prevention and treatment tools, including heat indices such as the WBGT, athlete management systems, and electronic medical records, will further prevent HRI and increase the availability and speed of data access during critical heat events, improving the clinical decision-making process for athletic trainers and physicians, sports scientists, employers, and military officers.

Hamstring Injury Prevention for Elite Soccer Players: A Real-World Prevention Program Showing the Effect of Players' Compliance on the Outcome.

ABSTRACT: Chebbi, S, Chamari, K, Van Dyk, N, Gabbett, T, and Tabben, M. Hamstring injury prevention for elite soccer players: A real-world prevention program showing the effect of players' compliance on the outcome. J Strength Cond Res 36(5): 1383-1388, 2022-The aim of this study was to determine the effect of implementing the Nordic hamstring exercise (NHE) to prevent hamstring injuries in soccer. A professional team was followed by the same medical team during 5 successive seasons (2012/2013 through 2016/2017). During the first and last seasons (2012/2013 and 2016/2017), no hamstring preventive action was implemented. For the seasons 2013/2014, 2014/2015, and 2015/2016, a noncompulsory (few players refusing to participate) NHE prevention program was implemented with accurate recording of the players' training and match exposure and attendance to the prevention sessions. The first 10 weeks of the season were used to progressively increase the volume and intensity of the NHE exercises, and at the end of the season, players were split in low-, moderate-, and high-attendance groups to the prevention sessions. Overall, 35 time-loss hamstring strain injuries were accounted for. The injury incidence was 0.30 per player per season, and the injury rate was 0.95 injury/1000 hour of exposure. A nonstatistically significant higher risk of hamstring injury was observed in the control, low, and moderate attendance groups compared with the high-attendance group. The greatest risk of hamstring injury was observed in the low-attendance group (odds ratio 1.77, confidence interval 0.57-5.47, p = 0.32). Implementing a NHE prevention program has a positive effect on the injury rate in a soccer team; however, the compliance of players with such interventions may be critical for its success.

Factors associated with neck pain in fighter aircrew: a systematic review and meta-analysis.

Neck pain is a common complaint among fighter aircrew, impacting workforce health and operational capability. This systematic review aimed to identify, evaluate and synthesise the current evidence for factors associated with the occurrence of neck pain among fighter aircrew. Six electronic databases were searched in June 2019 and updated in June 2020 utilising the maximum date ranges. Included studies were appraised for methodological quality, ranked according to level of evidence and relevant data extracted. Where methods were homogeneous and data availability allowed, meta-analyses were performed. A total of 20 studies (16 cross sectional, one case-control, one retrospective cohort and two prospective cohort) were eligible for inclusion. Of the 44 factors investigated, consistent evidence was reported for greater occurrence of neck pain among aircrew operating more advanced aircraft and those exposed to more desk/computer work, while another 12 factors reported consistent evidence for no association. Of the 20 factors where meta-analyses could be performed, greater occurrence of neck pain was indicated for aircrew: flying more advanced aircraft, undertaking warm-up stretching and not placing their head against the seat under greater +Gz. Despite many studies investigating factors associated with neck pain among fighter aircrew, methodological limitations limited the ability to identify those factors that are most important to future preventive programmes. High-quality prospective studies with consistent use of definitions are required before we can implement efficient and effective programmes to reduce the prevalence and impact of neck pain in fighter aircrew. PROSPERO registration number: CRD42019128952.Neck pain is a common complaint among fighter aircrew, impacting workforce health and operational capability. This systematic review aimed to identify, evaluate and synthesise the current evidence for factors associated with the occurrence of neck pain among fighter aircrew.

Match-Play Running Demands and Technical Performance Among Elite Gaelic Footballers: Does Divisional Status Count?

ABSTRACT: McGahan, JH, Mangan, S, Collins, K, Burns, C, Gabbett, T, and O'Neill, C. Match-play running demands and technical performance among elite Gaelic footballers: Does divisional status count? J Strength Cond Res 35(1): 169-175, 2021-The aim of the current study was to compare positional differences in running demands and technical performance variables among elite Gaelic football teams from separate divisions. Data were obtained from a division 1 (26.7 ± 2.9 years, 179.2 ± 21.3 cm, 89.9 ± 21.2 kg) and a division 3 (25.7 ± 3.5 years, 183.0 ± 4.7 cm, 84.4 ± 6.5 kg) team. Match-play running variables were collected using 4-Hz global positioning system (GPS) units (VX Sport; Visuallex Sport, Lower Hutt, New Zealand) (Match data sets; division 1: n = 107, division 3: n = 97). Selected variables assessed were high-speed running distance (HSR) (≥17 km·h-1), number of high-speed efforts (HSE) (≥17 km·h-1), relative high-speed distance (RHSD) (≥17 km·h-1; m·min-1), and percentage of time at high speed (%HS). Each variable was analyzed across the 5 positional groups in Gaelic football (full back, half back, midfield, half forward, full forward). The same 25 competitive games were analyzed using the GPS and the Sports Code video analysis system (Sports Code Elite V9; Sportstec, Warriewood, NSW, Australia). Technical performance variables selected for analysis were total kick/hand passes, tackles, shots, and percentage of time in possession. High-speed running distance running demands were differentiated between the divisions; the division 3 team demonstrated significantly greater HSR, HSE, RHSD, and %HS than the division 1 team (p ≤ 0.05). Positional-specific analysis found that the division 3 full back and midfield positional lines had significantly greater HSR, RHSD, and %HS than their division 1 counterparts. The division 1 team made a greater number of total tackles, with significantly more tackles in the middle third (p ≤ 0.05). The division 3 team performed a significantly greater number of hand passes and unsuccessful shots per game (p < 0.01). The results of this study indicate that overall technical proficiency, rather than high-speed running profiles, differentiate division 1 and 3 Gaelic football teams.

Influence of Workload and Recovery on Injuries in Elite Male Volleyball Players.

ABSTRACT: Timoteo, TF, Debien, PB, Miloski, B, Werneck, FZ, Gabbett, T, and Filho, MGb. Influence of workload and recovery on injuries in elite male volleyball players. J Strength Cond Res 35(3): 791-796, 2021-The aim of this study was to investigate the influence of workload and recovery on injury rates in elite male volleyball players. Data were collected from 14 male professional volleyball players over a 27-week season. Workloads were monitored daily using the session rating of perceived exertion, and recovery status was appraised using the Total Quality Recovery (TQR) scale. The players were exposed to 4,573.31 hours (h) of training and games with an overall injury incidence of 13.99 per 1,000 hours. Overuse accounted for 83% (11.58 injuries/1,000 hours) and trauma accounted for 17% (2.40 injuries per 1,000 hours) of all injuries. There was a higher incidence of injuries (p = 0.003), higher weekly workload (p = 0.008), and acute:chronic workload ratio (ACWR) (p < 0.001) in the pre-season compared with the competitive period. Healthy players had lower ACWR (p = 0.002) compared with the injured players. The TQR was higher for the healthy group compared with the injured group (p < 0.001). The greater odds of injury was related to higher ACWR (risk factor) (p = 0.014) and lower TQR values (p = 0.004) (protection factor). Athlete's workloads and the state of recovery may be related to injuries in volleyball. The results presented in this study emphasize the importance of controlling these variables in professional volleyball teams to prevent injuries.

Investigation in to the Positional Running Demands of Elite Gaelic Football Players: How Competition Data Can Inform Training Practice.

McGahan, J, Burns, C, Lacey, S, Gabbett, T, and Neill, CO. Investigation in to the positional running demands of elite Gaelic football players: How competition data can inform training practice. J Strength Cond Res 34(7): 2040-2047, 2020-This study investigated the positional running demands of elite Gaelic football players during match play and compared these demands with typical training activities used to prepare players for competition. Global positioning system (GPS) data were obtained from 30 elite Gaelic football players (26.9 ± 3.5 years, 182.8 ± 6.1 cm, 84.6 ± 8.1 kg) across a full season (13 competitive games and 78 training sessions). Only players who completed the full match and respective training sessions were included (n = 107 match files and n = 1,603 training files). Data were collected using 4-Hz GPS units (VX Sport, Lower Hutt, New Zealand). Mean high speed (≥17 km·h; m·min), mean speed (m·min), percentage at high speed (%), and mean sprint efforts (≥17 km·h; no.·min) were recorded. Running variables were analyzed across the 5 outfield positional lines in Gaelic football (full back [FB], half back [HB], midfield [MF], half forward, and full forward [FF]). For mean high-speed running and mean speed, significant relationships (range r = 0.811-0.964 and r = 0.792-0.998, respectively) were found between competition and game-based training for players in the FB, HB, MF, and FF lines (p ≤ 0.05). Analyses of mean sprint efforts and percentage at high speed found positive correlations between competition and training activities across each of the positional lines. Appropriately designed training activities can ensure that the position-specific demands of elite Gaelic football competition are met using a game-based training approach. Collectively, these findings demonstrate the value of and provide support for the use of a game-based training approach as a method of preparing players for the physical demands of competition in elite Gaelic football.

Training and match volume and injury in adolescents playing multiple contact team sports: A prospective cohort study.

Training and competition loads have emerged as valuable injury risk factors but very few studies have explored injury outcomes in adolescent athletes. The aims of this study were to describe injuries and to explore the relationship between training and match load volumes and injury in adolescent athletes participating in multiple contact team sports. One hundred and three male youth rugby athletes aged 14-16 years from 8 rugby union teams were prospectively monitored during a season for weekly training and match volumes and injuries. The relationship between volume and injury was explored by comparing the weekly volume in the week prior to an injury vs weeks without injury. There were 83 time-loss injuries in 58 athletes (62%). Overall injury incidence was 18.5 per 1000 player-hours. Mean weekly injury prevalence was 27% (95% CI 25-30). Average weekly volume was 5.4 (2.2) hours comprising 1.4 (1) match hours and 4 (2.6) training hours. Compared with weeks without injury, weeks prior to an injury had higher match volumes (110 [57] min vs 83 [59] min, P < 0.001). Poisson regression demonstrated that match volume was a predictor of injury with an odds ratio of 1.41 (P = 0.001). The contribution of match volumes to injury risk and the relatively high injury burden in these athletes may be profound. Very high match volumes are unlikely to be in the best interests of young athletes and could be avoided with a systematic approach to load management and athlete development.

To Couple or not to Couple? For Acute:Chronic Workload Ratios and Injury Risk, Does it Really Matter?

We examined the association between coupled and uncoupled acute:chronic workload ratios (ACWR) and injury risk in a cohort of 28 elite cricket fast bowlers (mean±SD age, 26±5 yr). Workloads were estimated using the session rating of perceived exertion (session-RPE). Coupled ACWRs were calculated using a 1-week acute workload and 4-week chronic workload (acute workload was included in the chronic workload calculation), whereas uncoupled ACWRs used the most recent 1-week acute workload and the prior 3-week chronic workload (acute workload was not included in the chronic workload calculation). A nearly perfect relationship (R2=0.99) was found between coupled and uncoupled ACWRs. Using a percentile rank method, no significant differences in injury risk were found between the coupled and uncoupled ACWR. Higher ACWRs were associated with increased injury likelihood for both coupled and uncoupled methods, however there were no significant differences in injury risk between coupled and uncoupled ACWRs. Our data demonstrates that both coupled and uncoupled ACWRs produce the same injury likelihoods. Furthermore, our results are consistent with previous studies: higher ACWRs are associated with greater risk, irrespective of whether acute and chronic workloads are coupled or uncoupled.

The Influence of Contextual Factors on Running Performance in Female Australian Football Match-Play.

Black, GM, Gabbett, TJ, Naughton, G, Cole, MH, Johnston, RD, and Dawson, B. The influence of contextual factors on running performance in female Australian football match-play. J Strength Cond Res 33(9): 2488-2495, 2019-Given the recent growth of the professional status among multiple female football codes, the aim of this study is to investigate the effects of contextual factors on activity profiles and pacing strategies in female Australian football (AF) players. Thirty-five female AF players participated in this study. Global positioning system analysis was completed over 1 competitive season. Matches were separated into eight 10-minute periods. Greater distances were covered during the first half irrespective of playing position (effect size [ES] = 0.39-0.50, Likelihood ≥90%). Throughout a number of periods half-backs (defensive players) covered greater distances during losses (ES ≥ 0.74, Likelihood ≥92%) and against top 3 opponents (ES ≥ 1.0, Likelihood ≥97%). Midfielders and half-backs covered greater distances (ES ≥ 0.49, Likelihood ≥89%) in the final match period in winning compared with losing matches. A reduction in player work rate is evident during the second half of matches. The influence of contextual factors varied across positional groups. However, it is clear that coaches could use player rotation both early in the match in an attempt to delay the effect of fatigue and more frequently during the second half to increase running intensity.

Sex Differences in Physical Fitness Characteristics and Match-Play Demands in Adolescent Netball: Should Male and Female Adolescents Co-compete in Netball?

Tissera, KM, Naughton, GA, Gabbett, TJ, Krause, LM, Moresi, MP, and Benson, AC. Sex differences in physical fitness characteristics and match-play demands in adolescent netball: Should male and female adolescents co-compete in netball? J Strength Cond Res 33(3): 846-856, 2019-Sports participation offers multifaceted benefits, especially during adolescence. However, policies relating to male and female adolescents co-competing in team sports can be prohibitive and lack an evidence base. This study aimed to strengthen evidence on coparticipation of male and female adolescents playing recreational netball. Off-court fitness characteristics (power, speed, agility, and high-speed intermittent running) and match-play performances from global positioning system (GPS) and video analysis were compared in adolescent males (n = 34, mean ± SD, age, 15.2 ± 0.8 years) and females (n = 45, mean ± SD, age, 14.9 ± 0.7 years), with previous recreational netball experience. Independent t-tests showed adolescent men outperforming females in all off-court fitness characteristics (p < 0.001). Two-way analyses of variance explored sex-based interactions in match-play (GPS accelerometer data and notational analyses) and type of competition (mixed-/single-sex formats) in forty-two 7-minute matches. Overall, no differences in match-play performances were found between males and females (p > 0.05). Notational skill-based comparisons showed that male skills were better in mixed- than single-sex matches. Conversely, competition format did not alter skills of females. Despite more netball experience in females and superior off-court fitness characteristics in males, on-court performance differences between males and females were minimal in these recreational adolescent netball players. Coparticipation in netball was not detrimental to the performance of either sex.

The most demanding passages of play in football competition: a comparison between halves.

The purpose of this investigation was to determine the differences between halves in the most demanding passages of play in football players according to playing position and duration-specific activity. Global positioning system data were collected from twenty-three football players from a reserve squad of the Spanish La Liga. A total of 265 individual match half data were analysed across the competitive season. Players were categorised based on positional groups: full-back (FB), central defender (CD), midfielder (MF), offensive midfielder (OMF) and forwards (FW). The most demanding passage of match play was analysed using a rolling average method, where maximal values were calculated for five different time durations (1, 3, 5, 10 min and half completed) using distance (m·min-1), high metabolic load distance (HMLD; m·min-1) and average metabolic power (AMP; W·kg-1) as variables of interest. The differences between the first and second half increased as the rolling duration increased, reaching the greatest difference between halves in the complete half (45 min) in all the variables studied (ES = 0.54 ± 0.15, 0.75 ± 0.15 and 0.76 ± 0.15 in distance, HMLD and AMP). The CDs were the players that presented the greatest differences, and it was in the AMP variable where the greatest differences between the first and second half were found. Large decreases in AMP were found for CD (ES = -1.30 ± 0.36) and moderate decreases were found in AMP for FB (ES = -0.84 ± 0.30) and OMF (ES = -0.78 ± 0.37). These results provide insight into the most demanding passages of play to inform training practices for specific football playing positions.

Activity and recovery cycles and skill involvements of successful and unsuccessful elite rugby league teams: A longitudinal analysis of evolutionary changes in National Rugby League match-play.

We investigated changes in activity and recovery cycles and skill involvements: (1) during National Rugby league (NRL) match-play from 2004 to 2014 and (2) among successful and unsuccessful teams over the same period. Teams were divided into 4 tiers according to final ladder position: (A) 1st-4th, (B) 5th-8th, (C) 9th-12th and (D) 13th-16th. Total, mean and maximum ball-in-play time decreased, while recovery time increased from 2004 to 2014. Offensive and defensive skill involvements changed differentially over time with moderate to large reductions in the number of play-the-balls, offloads and missed tackles, and moderate to large increases in the number of passes, tackles made and ineffective tackles. The gap between Tier A and Tier D decreased for mean activity time and the proportion of short (<45 s) ball-in-play periods. Conversely, the gap between Tier A and Tier D increased for skill involvements, with Tier A completing more play-the-balls, and Tier D performing a greater number of offloads, and total, missed and ineffective tackles. Our results demonstrate the decreasing ball-in-play demands of NRL competition over 11 seasons. However, our data also highlight the narrowing gap in ball-in-play demands, and increasing gap in skill involvements between the top tier and bottom tier teams.

The Use of Generic and Individual Speed Thresholds for Assessing the Competitive Demands of Field Hockey.

The current study compared the running demands of professional field hockey players using individualized speed zones and generic default settings of the GPS manufacturer. In addition, the differences in slow, moderate and fast players were studied. Sixteen male players from the same club participated in the study (age: 25.5 ± 2.9 years; body mass: 74.6 ± 5.5 kg; stature 1.77 ± 0.05 m). The peak speed of each participant was established at the end of the data collection period by analyzing all training and playing data throughout the season. Using players peak speed achieved for each participant during the season, individualized speed zones were retrospectively applied to all match-play data. Peak speed was used to categorize players into three groups, slow (5 players: 29.2-30.2 km·h-1), moderate (6 players: 30.7-31.5 km·h-1) and fast (5 players: 32.2-33.7 km·h-1). Significant differences were observed between generic and individual thresholds for the distance covered in moderate, high, and very high-speed running in all positions (p = 0.01). Our findings show that the distances covered at high-speeds in midfielders and forwards were overestimated, while the very high-speed running and sprinting in backs were underestimated. Generic speed thresholds should be used if comparisons between positions is of importance. However, based on the different capacities of field hockey players, individual speed thresholds may be more suitable when addressing the relative stress on individual athletes.

Positional Differences in the Most Demanding Passages of Play in Football Competition.

The aim of this investigation was to determine the position and duration specific activity of the most demanding passages of play in football players. Global positioning system data were collected from twenty-three football players across a competitive season. A total of 605 individual match files were analysed. Players were categorised based on positional groups; full-back (FB), central defender (CD), midfielder (MF), wide midfielders (WMF) and forwards (FW). The most demanding passage of a match play was analysed using a rolling average method, where maximal values were calculated for four different time durations (1', 3', 5' and 10') using distance (m·min-1), high metabolic load distance (HMLD) and average metabolic power (AMP) as variables of interest. Using distance as the criterion variable, MF and WMF positions covered greater distance, and fewer sprinting meters (>7.0 m·s-1, m·min-1). With HMLD as the criterion variable, the values for WMF and MF positions were higher than the CD and FW positions. The MF and WMF positions performed more high-intensity accelerations and decelerations when the criterion variable was AMP. These results provide an understanding of the most demanding passages of play to inform training practices for specific football playing positions.

How do training and competition workloads relate to injury? The workload-injury aetiology model.

Injury aetiology models that have evolved over the previous two decades highlight a number of factors which contribute to the causal mechanisms for athletic injuries. These models highlight the pathway to injury, including (1) internal risk factors (eg, age, neuromuscular control) which predispose athletes to injury, (2) exposure to external risk factors (eg, playing surface, equipment), and finally (3) an inciting event, wherein biomechanical breakdown and injury occurs. The most recent aetiological model proposed in 2007 was the first to detail the dynamic nature of injury risk, whereby participation may or may not result in injury, and participation itself alters injury risk through adaptation. However, although training and competition workloads are strongly associated with injury, existing aetiology models neither include them nor provide an explanation for how workloads alter injury risk. Therefore, we propose an updated injury aetiology model which includes the effects of workloads. Within this model, internal risk factors are differentiated into modifiable and non-modifiable factors, and workloads contribute to injury in three ways: (1) exposure to external risk factors and potential inciting events, (2) fatigue, or negative physiological effects, and (3) fitness, or positive physiological adaptations. Exposure is determined solely by total load, while positive and negative adaptations are controlled both by total workloads, as well as changes in load (eg, the acute:chronic workload ratio). Finally, we describe how this model explains the load-injury relationships for total workloads, acute:chronic workload ratios and the training load-injury paradox.

Calculating acute:chronic workload ratios using exponentially weighted moving averages provides a more sensitive indicator of injury likelihood than rolling averages.

OBJECTIVE: To determine if any differences exist between the rolling averages and exponentially weighted moving averages (EWMA) models of acute:chronic workload ratio (ACWR) calculation and subsequent injury risk. METHODS: A cohort of 59 elite Australian football players from 1 club participated in this 2-year study. Global positioning system (GPS) technology was used to quantify external workloads of players, and non-contact 'time-loss' injuries were recorded. The ACWR were calculated for a range of variables using 2 models: (1) rolling averages, and (2) EWMA. Logistic regression models were used to assess both the likelihood of sustaining an injury and the difference in injury likelihood between models. RESULTS: There were significant differences in the ACWR values between models for moderate (ACWR 1.0-1.49; p=0.021), high (ACWR 1.50-1.99; p=0.012) and very high (ACWR >2.0; p=0.001) ACWR ranges. Although both models demonstrated significant (p<0.05) associations between a very high ACWR (ie, >2.0) and an increase in injury risk for total distance ((relative risk, RR)=6.52-21.28) and high-speed distance (RR=5.87-13.43), the EWMA model was more sensitive for detecting this increased risk. The variance (R2) in injury explained by each ACWR model was significantly (p<0.05) greater using the EWMA model. CONCLUSIONS: These findings demonstrate that large spikes in workload are associated with an increased injury risk using both models, although the EWMA model is more sensitive to detect increases in injury risk with higher ACWR.

Training load--injury paradox: is greater preseason participation associated with lower in-season injury risk in elite rugby league players?

AIM: To determine whether players who completed a greater number of planned preseason training sessions were more or less likely to be injured during the competitive season. METHODS: A cohort of 30 elite rugby league players was prospectively studied during their 17-week preseason and 26-round competitive season. Injuries were recorded using a match time loss definition. Preseason participation was quantified as the number of 'full' training sessions that players completed, excluding modified, rehabilitation or missed sessions. In-season training load variables, collected using global positioning system (GPS) data, included distance covered (m), high-speed distance covered (m) and the percentage of distance covered at high speeds (%). Multilevel logistic regression models were used to determine injury likelihood in the current and subsequent week, with random intercepts for each player. Odds ratios (OR) were used as effect size measures to determine the changes in injury likelihood with (1) a 10-session increase in preseason training participation or (2) standardised changes in training load variables. RESULTS: Controlling for training load in a given week, completing 10 additional preseason sessions was associated with a 17% reduction in the odds of injury in the subsequent week (OR=0.83, 95% CI=0.70 to 0.99). Increased preseason participation was associated with a lower percentage of games missed due to injury (r=-0.40, p<0.05), with 10 preseason sessions predicting a 5% reduction in the percentage of games missed. CONCLUSIONS: Maximising participation in preseason training may protect elite rugby league players against in-season injury.

Managing player load in professional rugby union: a review of current knowledge and practices.

BACKGROUND: The loads to which professional rugby players are subjected has been identified as a concern by coaches, players and administrators. In November 2014, World Rugby commissioned an expert group to identify the physical demands and non-physical load issues associated with participation in professional rugby. OBJECTIVE: To describe the current state of knowledge about the loads encountered by professional rugby players and the implications for their physical and mental health. FINDINGS: The group defined 'load' as it relates to professional rugby players as the total stressors and demands applied to the players. In the 2013-2014 seasons, 40% of professional players appeared in 20 matches or more, and 5% of players appeared in 30 matches or more. Matches account for ∼5-11% of exposure to rugby-related activities (matches, team and individual training sessions) during professional competitions. The match injury rate is about 27 times higher than that in training. The working group surmised that players entering a new level of play, players with unresolved previous injuries, players who are relatively older and players who are subjected to rapid increases in load are probably at increased risk of injury. A mix of 'objective' and 'subjective' measures in conjunction with effective communication among team staff and between staff and players was held to be the best approach to monitoring and managing player loads. While comprehensive monitoring holds promise for individually addressing player loads, it brings with it ethical and legal responsibilities that rugby organisations need to address to ensure that players' personal information is adequately protected. CONCLUSIONS: Administrators, broadcasters, team owners, team staff and the players themselves have important roles in balancing the desire to have the 'best players' on the field with the ongoing health of players. In contrast, the coaching, fitness and medical staff exert significant control over the activities, duration and intensity of training sessions. If load is a major risk factor for injury, then managing training loads should be an important element in enabling players to perform in a fit state as often as possible.