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

Preseason Workload in Collegiate Baseball Pitchers

Background

Upper extremity injuries are common in baseball spanning from youth through professional leagues, especially in preseason. Although there are some arbitrary guidelines for number of throws during practices and games, there is no current information on workload during preseason in baseball pitchers.

Hypothesis/Purpose

The purpose of this study was to quantify the number of throws and workload, as defined by angular velocity, during preseason training in a collegiate baseball season.

Study Design

Descriptive Epidemiology Study.

Methods

Nine baseball pitchers wore an inertial measurement unit on the forearm during all preseason training. Movements were captured at 100Hz and classified as a throw when the forearm velocity was greater than 800°/second. Peak angular velocity was exported for each throw and total workload was calculated as the median angular velocity multiplied by total throws for each day. Chronic workload was calculated as the rolling 28 days average workload and acute workload was calculated as the average seven-day workload. Acute to chronic workload ratio (ACWR) was calculated for each week. A repeated measures ANOVA with pairwise comparisons was used to compare throws, acute workload, and ACWR between weeks. Cohen's d effect sizes were calculated for all significant differences.

Results

The pitchers averaged 1990.6 ± 881.7 throws throughout preseason at an average angular velocity of 1686.2 ± 334.9 m/s. Acute workload was reduced in Week 4 compared to Week 2 (p=0.018, d=1.73) and week 3 (p=0.007, d =2.30). ACWR was above 1.27 on weeks 1,2,3, and 5. ACWR was significantly reduced in week 4 (0.79) compared to week 3 (1.50; p=0.021, d =0.71).

Conclusion

ACWR was above 1.27 for four of the six weeks of preseason, suggesting that there may be a need to reduce workload and progressively build during the preseason. Clinicians should consider monitoring workload during preseason throwing to decrease risk of chronic overuse injuries.

Level of Evidence

2c.

Investigating the effects of previous injury on subsequent training loads, physical fitness, and injuries in youth female basketball players

Background

Previous studies have shown that athletes accustomed to higher chronic workloads are less susceptible to injury than those exposed to lower chronic workloads. However, few studies have evaluated whether previous injury influences them. Therefore, this study investigated the impact of previous injuries on subsequent training loads, physical fitness, and injury rates in female youth basketball players.

Methods

Training load, physical fitness, and injuries of 18 young female basketball players (age 16.8 ± 1.4 years) were monitored. Previous injury status was clustered using the K-means clustering algorithm to separate players into high-risk and low-risk groups. Linear mixed models were used to analyze the effects of previous injury status on subsequent training load and physical fitness. Meanwhile, the differences between the players' injury groups were analyzed.

Results

Previous injury status can significantly impact a player's subsequent training loads, including acute loads, chronic loads, skill-based training loads, training monotony, and training strain (all p < 0.05). The two groups had no significant differences in physical fitness (all p > 0.05). Furthermore, the incidence of non-contact injuries was significantly higher in the high-risk group than low-risk group, which would result in more training time lost (all p < 0.05).

Conclusion

This study identified the impact of previous injury status on subsequent training load, physical fitness, and injuries in youth female basketball players. These findings provide valuable insight for coaches to optimize training loads according to previous injury status, aiming to minimize the likelihood of subsequent injuries.

"Health is Just the Basic Requirement for Optimal Performance and Winning": Stakeholders' Perceptions on Testing and Training in Competitive Alpine Skiing, Snowboarding and Freestyle Skiing

BACKGROUND AND OBJECTIVE

Competitive alpine skiing, snowboarding and freestyle skiing, all different in nature and risks, are known for their high injury and illness burden. Testing measures and training methods may be considered for athletes' preparation to support performance enhancement while safeguarding their health. We explored the perspectives and perceptions of competitive alpine skiing, snowboarding and freestyle skiing stakeholders regarding testing and training practices in their competitive snow sports.

METHODS

We conducted an exploratory qualitative study based on grounded theory principles through 13 semi-structured interviews about testing and training practices with athletes, on-snow and off-snow coaches, managers and healthcare providers from different national teams. The interviews were inductively analysed through a constant comparative data analysis.

RESULTS

Participants described winning as the end goal of testing and training practices, which requires athletes to perform in their best condition. To do so, they mentioned two main targets: performance enhancement and health protection. Participants acknowledged health as a premise to perform optimally, considering testing and monitoring approaches, goal setting, and training to support and protect athlete performance. This continuous cyclic process is driven by communication and shared decision making among all stakeholders, using testing and monitoring outputs to inform goal setting, training (e.g. on-snow and off-snow) and injury prevention. Such an approach helps athletes achieve their goal of winning while being fit and healthy throughout their short-term and long-term athletic career development.

CONCLUSIONS

The ultimate goal of testing measures and training methods in such competitive snow sports is winning. Performance enhancement and health protection act as pillars in systematic, tailored and flexible processes to guarantee athletes' best preparation to perform. Moreover, athletes' assessments, goal setting, monitoring tools, open communication and shared decision making strongly guide this cyclic process.

Effects of prevention programmes on injury risk in military personnel: a systematic review with meta-analysis

INTRODUCTION

Exercise programmes have been used to prevent injuries in military personnel, as they can reduce modifiable risk factors for injuries. Our aim was to review the literature to evaluate the effects of different exercise protocols on the prevention of injuries in military personnel.

METHODS

A systematic literature review examined the effects of different exercise protocols on the prevention of musculoskeletal injuries in the military. Several databases were explored to find experimental studies that investigated the effects of prevention programmes on the risk of injury. We have extracted from the studies: profile of participants, sample size, study design and characteristics of the control group (CG), the type of intervention and the relative risk (RR) in the experimental group and CG, with their significance levels. For data analysis, we used the RevMan V.5.3 software. The measure of RR was investigated. The risk of publication bias was analysed with Begg's test.

RESULTS

A total of 13 694 titles and studies were recovered from the databases and by manual search. After the removal of duplicate titles and studies that did not meet the eligibility criteria, 17 studies were selected. The protocols were composed of neuromuscular training, stretching, agility training or combined exercises. The meta-analysis showed that injury prevention exercise programmes reduced the risk of musculoskeletal injuries in military personnel by 14% (RR=0.86; 95% CI=0.76 to 0.98).

CONCLUSION

Injury prevention exercise programmes promoted a slight reduction in the risk of musculoskeletal injuries in military personnel.

LEVEL OF EVIDENCE

Very low.

TRIAL REGISTRATION NUMBER

CRD 42017077946.

Monitoring training load and perceived recovery indicators during the preseason and in-season phases in professional female basketball players

BACKGROUND

During the basketball season, it is essential to carefully plan training and recovery activities to optimize players' performance. This study monitored training load and perceived recovery indicators in professional female basketball players across the preseason and in-season phases.

METHODS

Seventeen professional female basketball players (age: 19.6±3.1 years; height: 180.2±5.9 cm; playing position: 8 backcourt, 9 frontcourt) were monitored for eleven consecutive weeks. Each morning, players reported their perceived recovery using a 10-point Total Quality of Recovery (TQR) Scale. After each training session or game, players reported their perceived exertion using the CR-10 Scale, which was multiplied by the duration of the training or game to obtain the session load. Weekly load, monotony, strain, TQRAM (morning recovery) and TQRfw (recovery at the start of the following week) were calculated. Linear mixed models were performed to assess the effects of season phase (preseason; in-season), playing position (backcourt; frontcourt) and group (senior; under) on load and recovery variables.

RESULTS

Weekly load, monotony and strain were higher in the preseason than the in-season phase (all P<0.001, ES: moderate-large). Strain was higher in senior players compared to under (P=0.045, ES: small). Regarding recovery variables, no effects were found for TQRAM, while TQRfw was higher in the preseason than in-season (P<0.001, ES: moderate) phase.

CONCLUSIONS

Professional female basketball players experience lower internal loads but poorer perceived recovery during the in-season phase. Practitioners should carefully consider the stress of competition and the cumulative fatigue from high preseason loads during the transition from the preseason to the regular season.

Assessing pre-season workload variation in professional rugby union players by comparing three acute:Chronic workload ratio models based on playing positions

Quantifying the pre-season workload of professional Rugby Union players, in relation to their respective positions not only provides crucial insights into their physical demands and training needs but also underscores the significance of the acute:chronic workload ratio (ACWR) in assessing workload. However, given the diversity in ACWR calculation methods, their applicability requires further exploration. As a result, this study aims to analyze the workload depending on the player's positions and to compare three ACWR calculation methods. Fifty-seven players were categorized into five groups based on their playing positions: tight five (T5), third-row (3R), number nine (N9), center, and third line defense (3L). The coupled and uncoupled rolling averages (RA), as well as the exponentially weighted moving average ACWR method, were employed to compute measures derived from GPS data. Changes throughout the pre-season were assessed using the one-way and two-way analysis of variance. The results revealed that N9 covered significantly greater distances and exhibited higher player load compared to T5 and 3L [p < 0.05, effect size (ES) = 0.16-0.68]. Additionally, 3L players displayed the highest workload across various measures, including counts of accelerations and decelerations (>2.5 m s-2), accelerations (>2.5 m s-2), acceleration distance (>2 m s-2), high-speed running (>15 km h-1), very high-speed running (>21 km h-1, VSHR), sprint running (>25 km h-1, SR) distance. When using coupled RA ACWR method, centers exposed significantly greater values to T5 (p < 0.05, ES = 0.8) and 3R (p < 0.05, ES = 0.83). Moreover, centers exhibited greater (p < 0.05, ES = 0.67-0.91) uncoupled RA ACWR values for VHSR and SR than T5 and 3R. When comparing the three ACWR methods, although significant differences emerged in some specific cases, the ES were all small (0-0.56). In light of these findings, training should be customized to the characteristics of players in different playing positions and the three ACWR calculation methods can be considered as equally effective approaches.

In-Game Workload Demands of Position Players in Major League Baseball

BACKGROUND

Athletes who are well prepared for the physical demands of competition are less susceptible to injury. Defining and then preparing athletes for these in-game demands is critical to athlete health and performance. The injury burden within Major League Baseball (MLB) is significant and differs by position. Despite its importance, the workload demands have not been described for position players in MLB.

HYPOTHESIS

That running demands would be significantly higher for outfielders, followed by infielders, and catchers, respectively, while batting and baserunning metrics would be similar across positions.

STUDY DESIGN

Cohort study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Total and high-speed running distance (>75% Vmax), high-speed running count, hard accelerations (>2.78 m/s/s), defensive and baserunning minutes, total and hard throws (>75% max), and bat swing counts were calculated from Statcast data. Players with 100 games or more in the 2018 season (n = 126) were included for analysis.

RESULTS

All offensive and baserunning metrics were similar across positions; however, significant positional differences were observed for defensive and overall workload metrics. High-speed running was highest among outfielders (F1,7 = 27.1, P < 0.01), followed by infielders, then catchers. Hard accelerations (F1,7 = 12.9, P < 0.01) were highest among first basemen, then outfielders, remaining infielders, and catchers. Total throws (F1,7 = 17.7, P < 0.01) were highest among middle infielders. Hard throws (P < 0.01) were highest among shortstops and third basemen.

CONCLUSION

In-game workloads differ significantly by defensive position in MLB. These differences in running, throwing, and hitting volumes have significant implications for physical preparation and injury return-to-play progressions to optimize performance and minimize injury and reinjury risk for these athletes.

CLINICAL RELEVANCE

These data provide insight into how best to prepare athletes of different positions for the demands of the game both in terms of preseason preparation as well as return-to-play benchmarks following injury. These data should also serve as a platform for future research into the relationship between workload and injury among professional baseball players.

Acute Response to Training after Returning from the Off-Season in Elite Rugby League Athletes

The purposes of this study were to quantify the physiological response to the initial two-week preseason period in elite male rugby league (RL) athletes, and to determine if a repeated bout effect (RBE) occurs. Eighteen RL players were monitored for the initial two-week preseason period. Blood samples were collected on days (D)1, D2, D4, D5, D8, D9, D11 and D12 to measure creatine kinase (CK). Neuromuscular power was assessed on D1, D5, D8 and D12. During field-based sessions, the external training load was quantified using global positioning system technology, whilst the internal load was quantified using the training impulse and the session rating of perceived exertion. Resistance-based gym session volume was quantified by total repetitions x weight lifted. Perceived measures of fatigue and muscle soreness were assessed on all training days. Two-way (day x week) repeated measures analysis of variance and Bonferroni's corrected post-hoc tests identified significant changes. There were no significant changes in CK activity (649.2 ± 255.0 vs. 673.8 ± 299.1 µL; p = 0.63) or internal training load measures from week 1 to week 2. External training load measures including total distance (4138.1 ± 198.4 vs. 4525.0 ± 169.2 m; p < 0.001) and repeated high-intensity efforts (12.6 ± 1.8 vs. 17.5 ± 1.8 au; p < 0.001) significantly increased in week 2 compared to week 1. Internal training loads and CK activity did not change in response to an increase in external training loads during the initial preseason. The current results provide support for a 'real world' perspective of the RBE phenomenon that may be more applicable for team sport practitioners.

Noncontact Injury Distribution and Relationship With Preseason Training Load and Nonmodifiable Risk Factors in Rugby Union Players Across Multiple Seasons

ABSTRACT

Evans, SL, Whittaker, G, Elphinstone Davis, E, Jones, ES, Hardy, J, and Owen, JA. Noncontact injury distribution and relationship with preseason training load and non-modifiable risk factors in Rugby Union players across multiple seasons. J Strength Cond Res 37(7): 1456-1462, 2023-This study examined the distribution of noncontact injury during phases of the competitive season and the association between preseason training load (TL) and nonmodifiable risk factors on injury risk during these phases. Injury data were recorded from 1 senior academy team over 3 seasons (2017-2020) and analyzed across early-season, midseason, and late-season phases. A generalized estimating equation was used to model risk factors with noncontact injury for selected phases. The highest noncontact injury incidence occurred in the late-season phase (22.2 per 1,000 hours) compared with early (13.7 per 1,000 hours, p < 0.001) and midseason phases (15.5 per 1,000 hours, p = 0.001). Low preseason TL (8,949-12,589 arbitrary units; odds ratio [OR], 95% confidence interval [CI] = 4.7, 1.0-21.6; p = 0.04) and low preseason TL combined with high early-season TL and injury in the early-season phase (OR, 95% CI = 6.5, 1.1-35.5; p = 0.03) were associated with greater midseason noncontact injury risk. In addition, low preseason TL combined with previous injury was associated with increased risk of noncontact injury risk in the late season (OR, 95% CI = 12.2, 0.9-15.6, p = 0.05). Our results suggest players are at a greater injury risk during the late-season phase, with low preseason cumulative loads combined with a history of previous injury associated with increased in-season injury risk. Strength and conditioning coaches should therefore monitor cumulative preseason TL alongside screening for previous injury history to identify athletes at greater risk of noncontact injury risk during the competitive season.

It Takes Two to Tango: High Rates of Injury and Concussion in Ball Carriers and Tacklers in High School Boys' Rugby

OBJECTIVE

To examine injury and concussion rates, mechanisms, locations, and types of injury in Canadian high school male rugby.

DESIGN

Prospective cohort study.

SETTING

High school male rugby.

PARTICIPANTS

A total of 429 high school players (2018: n = 225, 2019: n = 256) were recruited from 12 teams in 7 schools in Calgary, Canada.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Injury surveillance included baseline questionnaires, weekly exposure, and injury reports. Injuries included those requiring medical attention, resulted in time loss and/or inability to complete a session. Concussion was defined as per the fifth Consensus on Concussion in Sport, and all players with a suspected concussion were referred to a study sport medicine physician.

RESULTS

A total of 134 injuries were captured, leading to an injury incidence rate (IR) of 57.9/1000 hours [95% confidence intervals (CIs): 45.4-73.8]. Median time loss was 6 days (range: 0-90). Injuries to the head were the most common (40%), followed by shoulder (12%) and ankle (10%). The concussion IR was 22.0/1000 hours (95% CIs: 15.9-30.4), which was the most common injury type (38%), followed by sprain (20%) and strain (15%). Sixty-five percent of injuries occurred in the tackle (ball carrier 35%, tackler 30%) and 76% of concussions (ball carrier 41%, tackler 35%).

CONCLUSIONS

The rate of injury and concussion in Canadian youth high school male rugby is high, with tackle-related injuries and concussions the most common. Given this, there is a critical need for implementation of prevention strategies, in particular targeting concussion and the tackle event (eg, neuromuscular, tackle training, and law changes).

The Association between Pre-season Running Loads and Injury during the Subsequent Season in Elite Gaelic Football

The aim of this study was to determine if the quantity of running load performed in pre-season affects the incidence of injury in elite Gaelic footballers. It was hypothesized that a greater quantity of running loads completed will reduce the incidence rate of injury. A cohort of elite male Gaelic football players (n = 25) was prospectively monitored throughout one full season. This longitudinal study involved the collection of GPS data and injury data. Participants were retrospectively divided into two groups and assigned to a high (HTL, completed >50% of pre-season sessions, n = 13) or low (LTL, completed <50% of pre-season sessions, n = 12) training load group based on the percentage of pre-season sessions completed. Data for total distance, PlayerLoad™, meters covered at running speeds (4.0−4.84 m/s), meters covered at high running speeds (4.85−6.39 m/s), meters covered at sprint speeds (>6.4 m/s) and high-intensity running meters (high-speed running meters and sprint meters combined) were collected during all sessions. A one-way analysis of variance (ANOVA) was completed to understand the variation of external training load data across the different phases of the season. A series of repeated measures of ANOVA were subsequently completed to understand the variation of external training load data across seasonal phases within the training groups. Although the LTL group had a higher incidence rate of non-contact injuries (large effect size) per 1000 h of exposure in each phase of the season, statistical analysis revealed that there was no significant difference (F = 4.32, p = 0.173, partial η2 = 0.684, large) between the HTL (14.9 ± 4.17/1000 h) and the LTL (24.5 ± 7.36/1000 h) groups. Additionally, the HTL group was able to sustain greater running loads in the competitive phases of the season compared to the LTL group, total distance (F = 8.10, p < 0.001, partial η2 = 0.299, large), high-speed running distance (F = 8.74, p < 0.001, partial η2 = 0.304, large) and high-intensity running distance (F = 7.63, p < 0.001, partial η2 = 0.276, large). Furthermore, players who complete a greater proportion of running loads in pre-season may alter their body composition levels to more optimal levels, which in turn may reduce the risk of injury while also helping increase or maintain performance-related fitness markers such as aerobic fitness.

Caught on camera: a video assessment of suspected concussion and other injury events in women's rugby union

OBJECTIVES

The objective of this study was to identify and report the incidence and mechanisms of suspected injury and concussion in women's rugby union.

DESIGN

A cross-sectional video analysis study.

METHODS

Using video analysis of non-professional, single-angle footage, cases of suspected injury and concussion were identified and reported, based on content validation and consensus by eight rugby-specific researchers, therapists, and sport medicine physicians.

RESULTS

There were 225 suspected injuries recorded in 48 games [Suspected injury rate (IR) = 117.5/1000 h (95 % CI;102.6-133.9) or 4.7 suspected injuries per match]. The on-field medical attention IR was 95.0/1000 h (95 % CI;81.7-109.9: 3.8 per game). Suspected concussions accounted for 26 % of injuries (30.8/1000 h: 95 % CI;23.5-39.7: 1.2 per game). The attacking team sustained 64 % of suspected injuries. Permanent removal from play was observed for 29 % of suspected injuries. The most common suspected injury locations were head/neck (28.4 %) and lower extremity (27.6 %). The tackle accounted for 67.1 % of all suspected injuries, with a propensity of 11.2/1000 tackle events (95 % CI;9.5-13.2) or 3.1 tackle-related injuries/game. Of tackle-related injuries, 63.6 % were to the ball carrier while 52.2 % of tackle-related concussions were to the ball carrier.

CONCLUSION

This study adds to the growing body of literature examining women's rugby. The rate of suspected injury is high compared with other studies. It is acknowledged that these are suspected injuries not supported by prospective injury surveillance. The high proportion of suspected injuries that are tackle-related warrants specific attention to identify tackle characteristics associated with injury and concussion.

Effects of the Off-Season on Muscular Power in Professional Rugby League

PURPOSE

Periods away from training and competition are necessary for physical and mental restoration in sport. There is limited research investigating changes to physical qualities in rugby league following prolonged breaks. This study aimed to evaluate the effects of the off-season on muscular power in rugby league. In addition, this study aimed to determine whether the type and volume of training players chose to complete had any relationship to feelings of restoration and/or readiness to return to training.

METHODS

Twenty professional rugby league players participated in this study. Lower-body muscular power was evaluated using a countermovement jump prior to the off-season and at the recommencement of training. Players completed a questionnaire to identify training and activities completed during the break and to assess feelings of restoration and readiness to commence training. Linear regression was used to estimate the effects of the number of days off on muscular power. One-way repeated-measures analysis of variance was conducted to examine differences in lower-body power throughout the study. Spearman rank order correlation was calculated to determine the relationship between off-season activities and feelings of restoration and readiness.

RESULTS

Peak velocity and peak force significantly increased following the off-season break. There were significant relationships between mental restoration and upper-body resistance training, as well as physical restoration and full-body resistance training.

CONCLUSIONS

The off-season has a positive effect on a player's ability to generate muscular power. Coaches may want to encourage players to complete resistance training sessions with the aim simply to maintain training load and potentially help players to feel rested.

Tracking Systems in Team Sports: A Narrative Review of Applications of the Data and Sport Specific Analysis

Seeking to obtain a competitive advantage and manage the risk of injury, team sport organisations are investing in tracking systems that can quantify training and competition characteristics. It is expected that such information can support objective decision-making for the prescription and manipulation of training load. This narrative review aims to summarise, and critically evaluate, different tracking systems and their use within team sports. The selection of systems should be dependent upon the context of the sport and needs careful consideration by practitioners. The selection of metrics requires a critical process to be able to describe, plan, monitor and evaluate training and competition characteristics of each sport. An emerging consideration for tracking systems data is the selection of suitable time analysis, such as temporal durations, peak demands or time series segmentation, whose best use depends on the temporal characteristics of the sport. Finally, examples of characteristics and the application of tracking data across seven popular team sports are presented. Practitioners working in specific team sports are advised to follow a critical thinking process, with a healthy dose of scepticism and awareness of appropriate theoretical frameworks, where possible, when creating new or selecting an existing metric to profile team sport athletes.

ACL injury prevention: Where have we come from and where are we going?

Anterior cruciate ligament (ACL) injuries are one of the most common and severe knee injuries across sports. As such, ACL injury prevention has been a focus of research and sports medicine practice for the past three-plus decades. Examining the current research and identifying both clinical strategies and research gaps, the aim of this review is to empower clinicians and researchers with knowledge of where the ACL injury prevention literature is currently and where it is going in the future. This paper examines the mechanism of ACL injury prevention, screening, implementation, compliance, adherence, coronavirus, and areas of future research. Clinical significance: The time lag between research and practical implementation in general healthcare settings can be as long as 17 years; however, athletes playing sports today are unable to wait that long. With effective programs already established, implementation and adherence to these programs is essential. Strategies such as coaching education, increasing awareness of free programs, identifying barriers, and overcoming implementation obstacles through creative collaboration are just a few ways that could help improve both ACL injury prevention implementation and adherence.

Variability of External Intensity Comparisons between Official and Friendly Soccer Matches in Professional Male Players

The aims of this study were to compare the external intensity between official (OMs) and friendly matches (FMs), and between first and second halves in the Iranian Premier League. Twelve players participated in this study (age, 28.6 ± 2.7 years; height, 182.1 ± 8.6 cm; body mass, 75.3 ± 8.2 kg). External intensity was measured by total duration, total distance, average speed, high-speed running distance, sprint distance, maximal speed and body load. In general, there was higher intensity in OMs compared with FMs for all variables. The first half showed higher intensities than the second half, regardless of the type of the match. Specifically, OMs showed higher values for total sprint distance (p = 0.012, ES = 0.59) and maximal speed (p < 0.001, ES = 0.27) but lower value for body load (p = 0.038, ES = −0.42) compared to FMs. The first half of FMs only showed lower value for body load (p = 0.004, ES = −0.38) than FMs, while in the second half of OMs, only total distance showed a higher value than FMs (p = 0.013, ES = 0.96). OMs showed higher demands of high intensity, questioning the original assumption of FMs demands. Depending on the period of the season that FMs are applied, coaches may consider requesting higher demands from their teams.

Comparison of player-dependent and independent high-speed running thresholds to model injury risk in football

High-speed running (HSR) loads have been linked with non-contact injury risks in team-sports. This study investigated whether player-specific speed zones, reflecting individual fitness characteristics, impact the associations between non-contact injury and acute and chronic HSR loads. Semi-professional soccer players from two clubs (n = 47) were tracked over two seasons using 10 Hz GPS (5552 observations). HSR distances were calculated arbitrarily (≥5.5 m·s^-1), and in an individualised fashion based on the final speed of the 30-15 intermittent fitness test. Cumulative running loads were represented by exponentially weighted moving averages with 7-(acute) and 28-day (chronic) decay parameters. Physiotherapists collected non-contact, lower-limb, time-loss injury data (n = 101). Injury models using session type (training vs matches), coach, as well as arbitrary or individualised running loads were constructed via mixed-effect logistic regression. Session type had the largest effect on injury (training vs match OR = 0.28; 95%CI:0.17-0.44). Variations in individualised or arbitrary acute and chronic HSR loads within the mid-range of the observed data had negligible effects on predicted injury risk. However, the uncertainty of estimated effects at extreme values of acute and chronic HSR loads prevented any conclusive findings. Therefore, the efficacy of using customised speed thresholds in quantifying load for injury risk mitigation purposes remains unclear.

Preseason elimination impact on anterior cruciate ligament injury in the National Football League

BACKGROUND

Anterior cruciate ligament (ACL) injuries represent detrimental injuries in the National Football League (NFL). A significant portion of these injuries often occur in preseason exhibitions. The Coronavirus disease 2019 pandemic presented a unique disruption to preseason NFL football with the cancelation of all preseason games.

AIM

To compare the incidence of ACL tears through the first eight weeks of the NFL season in 2020 to the mean incidence over the previous 5 seasons (2015-2019) and determine if there was any change in incidence with the elimination of the preseason.

METHODS

NFL players who suffered ACL tears during the preseason and first eight weeks of the NFL season from 2015-2020 were identified. The number of ACL injuries for the 2015-2019 seasons was compared to the 2020 season for four different timeframes. For each analysis, the cumulative number of ACL injuries to that time point was used to calculate the percent difference for descriptive analysis. Additionally, the number of teams with at least one player suffering an ACL tear were identified and compared using Chi-Squared testing. Finally, a cumulative relative risk was calculated for each week played.

RESULTS

There were 14 ACL tears through the first four games of the 2020 season, a 118.8% (14 vs 6.4) increase in comparison to the 5-year average over the first 4 regular season weeks of 2015-2019. However, when accounting for injuries occurring during the preseason from 2015-2019, there were 18.6% (14 vs 17.2) fewer total ACL injuries through regular season week 4 with no significant difference in percentage of teams impacted when these preseason injuries were accounted for P = 0.394. Results were similar (19 vs 17.2) over 8 total games played (whether regular season or preseason), and over 8 regular season games (P = 0.196, P = 0.600).

CONCLUSION

The elimination of the NFL preseason resulted in a higher rate of injuries during the first 4 games of the regular season. However, these increases are offset by the injuries typically sustained during the preseason. This suggests there may be front-loading of injuries over the course of an NFL season, such that players may be more prone to injury when the intensity of play suddenly increases, whether in the preseason or regular season.

The PITCH study: pitcher injuries during the first 30 days of the coronavirus disease 2019 halted Major League Baseball season

Background

Major League Baseball (MLB) was among the first professional team sports leagues to resume play in the United States after public health measures related to the appearance of coronavirus disease 2019 caused interruptions to preseason training and major alterations to regular season play. There was a high level of concern that these athletes were ill-prepared for competition and would experience an increased risk of injury under the restricted play rules.

Methods

The data in our study were compiled using publicly accessible records of players placed on injured lists from 2015 to 2020. These records came from 4 open access websites: rotoworld.com, fangraphs.com, foxsports.com, and spotrac.com. All injuries were confirmed using the transaction database found on the official MLB website (mlb.com).

Results

A greater proportion of pitchers were injured during the first 30 days of the 2020 season compared to the first 30 days of any of the 5 prior seasons (29.74% vs. 11.72%, n=2190, P<.001). There was a demonstrated increase in injury risk in 2020 for the following anatomic locations: back and trunk, shoulder, upper arm and elbow, forearm and wrist, and hand and finger (P=.02; confidence interval [0.497-5.783]). When dividing the first month of play in 2020 into equal halves (15 days each), the number of relief pitcher injuries increased with time (60% vs. 78%, P=.04). Lastly, there was no proportional difference in placement on the short-term vs. long-term injured list.

Conclusion

A significantly large increase in soft tissue injuries in 2020 compared to the prior 5 seasons predominantly affected the trunk and the upper extremity of pitchers in the first 30 days of play. Alterations to preseason training and regular season play in the 2020 MLB season due to coronavirus disease 2019 may have been particularly disadvantageous to professional pitchers who are positioned at baseline, the most injury prone position.

Pectoralis Major Ruptures in the National Football League: Incidence, RTP, and Performance Analysis

Background:

While pectoralis major (PM) tears are rare injuries in National Football League (NFL) athletes (previous study reported only 10 PM ruptures between 2000 and 2010), the incidence of these injuries has increased over the past decade. The impact these injuries have on a player’s performance after return has not been measured.

Purpose/Hypothesis:

To identify player characteristics that may predispose to PM tears and to determine the impact of this injury on return to play and performance. We hypothesized that there would be no difference in performance between the year before and after their injury.

Study Design:

Descriptive epidemiology study.

Methods:

NFL players who experienced PM tears between the years 2010 and 2018 were identified using publicly available reports. Several individual player characteristics were identified and recorded, and the return-to-play rates after injury were determined for each position. The pre- and postinjury Pro Football Focus grades of players who met inclusion criteria were compared. A paired t test analysis of the change in player performance was used for analysis.

Results:

In this study, 63 ruptures were identified between 2010 and 2018. Linebackers had the highest incidence of PM tear compared with any other position. Of all injuries, 79.3% were sustained by defensive players. The majority of PM tears occurred during games. Only 6.9% of players who sustained the injury were suspended for performance-enhancing drug use during their professional career. A total of 85.7% of players returned to play in the NFL after injury. Among those who returned to play there were no significant changes in player performance from pre- to post-injury.

Conclusion:

NFL players demonstrated 85.7% return-to-play rates and no significant drop-off in performance after PM ruptures. During the time period studied, there was an increase in incidence of PM ruptures compared with the previous decade. Further investigation is needed to determine potential causes for the increased incidence of PM ruptures in NFL players.

Acute Effects of Training Loads on Muscle Damage Markers and Performance in Semi-elite and Elite Athletes: A Systematic Review and Meta-analysis

BACKGROUND

The relationship between exercise-induced muscle damage (EIMD) indicators and acute training loads (TL) is yet to be reviewed extensively in semi-elite and elite athlete populations.

OBJECTIVES

The objectives of this systematic review and meta-analysis were threefold: (1) to evaluate studies of EIMD following the initial period of the preseason in semi-elite and elite athletes: (2) to examine acute physiological and performance responses across two periods of the season with similar TL; and (3) to examine acute physiological and performance responses to acute changes in TL during the season.

METHODS

The CINAHL, PubMed, Scopus, SPORTDiscus and Web of Science databases were systematically searched for studies that investigated: (1) semi-elite or elite athletes in team or individual sports following a periodised training programme; and (2) measured acute responses to training. Studies were excluded if: (1) conducted in animals; (2) non-English language; or (3) a conference abstract, review or case report. The Kmet Quality Scoring of Quantitative Studies tool was used for study appraisal.

SYNTHESIS METHODS

Data were quantitatively analysed by generating forest plots to report test statistics for statistical significance and inter-trial heterogeneity.

RESULTS

Of the included studies (n = 32), athletes experienced greater creatine kinase (CK) concentrations (Z = 4.99, p < 0.00001, I² = 74%), inflammatory factors and other indirect measures of muscle damage in the initial phase of the preseason period compared to the off-season; there were no changes in CK (Z = 1.43, p = 0.15, I² = 74%) across two time points of similar TL; and there were concurrent increases in CK with increases in TL (Z = 4.26, p < 0.0001, I² = 36%) and vice versa (Z = 4.33, p < 0.0001, I² = 79%).The qualitative analysis identified that the response of inflammatory factors and other indirect measures of muscle damage to changes in load were inconclusive.

LIMITATIONS

This review included varying age, sex, sports and competition levels. The group level meta-analysis failed to identify within-athlete or position-specific differences across time.

CONCLUSION

Blood biomarkers of EIMD may not differ across periods of similar TL, however can be considered a sensitive monitoring tool for assessing responses following acute TL changes in semi-elite and elite athletes.

Training Load Monitoring Considerations for Female Gaelic Team Sports: From Theory to Practice

Athlete monitoring enables sports science practitioners to collect information to determine how athletes respond to training loads (TL) and the demands of competition. To date, recommendations for females are often adapted from their male counterparts. There is currently limited information available on TL monitoring in female Gaelic team sports in Ireland. The collection and analysis of female athlete monitoring data can provide valuable information to support the development of female team sports. Athletic monitoring can also support practitioners to help minimize risk of excessive TL and optimize potential athletic performance. The aims of this narrative review are to provide: (i) an overview of TL athlete monitoring in female team sports, (ii) a discussion of the potential metrics and tools used to monitor external TL and internal TL, (iii) the advantages and disadvantages of TL modalities for use in Gaelic team sports, and (iv) practical considerations on how to monitor TL to aid in the determination of meaningful change with female Gaelic team sports athletes.

Monitoring Prescribed and Actual Resistance Training Loads in Professional Rugby League

ABSTRACT

Redman, KJ, Connick, MJ, Beckman, EM, and Kelly, VG. Monitoring prescribed and actual resistance training loads in professional rugby league. J Strength Cond Res 35(6): 1604-1610, 2021-Coaches devote a considerable amount of time and effort prescribing and selecting exercises to elicit training adaptations. Adherence to the prescribed resistance training load may vary for a number of reasons. The aim of this study was to quantify the difference between prescribed and actual resistance training loads in a team of professional rugby league players. Training loads were quantified using volume load and training intensity throughout a season. The competition was categorized into preseason, early competition, mid-competition, and late competition. Twenty-seven players participated in this study. Four exercises were monitored: back squat, bench press, bench pull, and clean pull. A Friedman's test was used to assess differences between prescribed and actual training loads throughout different phases of the season, for different exercises, and during different weeks in a training block. There were significantly greater differences in prescribed and actual volume loads during the mid-competition in comparison to all other phases of the season (p < 0.01). Although players adherence to prescribed training intensity was significantly greater during the preseason compared with the remainder of the season (p < 0.05), they completed significantly less prescribed training load during week 1 in comparison to week 4 within a training block (p < 0.05). The results of this study demonstrate that regular monitoring of completed resistance training loads may be of greater importance to strength and conditioning coaches to assist in examining potential progress and fatigue or allow for more accurate prescription of load to enhance adaptation throughout a season.

Is the Acute: Chronic Workload Ratio (ACWR) Associated with Risk of Time-Loss Injury in Professional Team Sports? A Systematic Review of Methodology, Variables and Injury Risk in Practical Situations

BACKGROUND

The acute: chronic workload ratio (ACWR) is an index of the acute workload relative to the cumulative chronic workloads. The monitoring of physical workloads using the ACWR has emerged and been hypothesized as a useful tool for coaches and athletes to optimize performance while aiming to reduce the risk of potentially preventable load-driven injuries.

OBJECTIVES

Our goal was to describe characteristics of the ACWR and investigate the association of the ACWR with the risk of time-loss injuries in adult elite team sport athletes.

DATA SOURCES

PubMed, EMBASE and grey literature databases; inception to May 2019.

ELIGIBILITY CRITERIA

Longitudinal studies that assess the relationship of the ACWR and time-loss injury risk in adult professional or elite team sports.

METHODS

We summarized the population characteristics, workload metrics and ACWR calculation methods. For each workload metric, we plotted the risk estimates for the ACWR in isolation, or when combined with chronic workloads. Methodological quality was assessed using a modified version of the Downs and Black scale.

RESULTS

Twenty studies comprising 2375 injuries from 1234 athletes (all males and mean age of 24 years) from different sports were included. Internal (65%) and external loads (70%) were collected in more than half of the studies and the session-rating of perceived exertion and total distance were the most commonly collected metrics. The ACWR was commonly calculated using the coupled method (95%), 1:4 weekly blocks (95%) and subsequent week injury lag (80%). There were 14 different binning methods with almost none of the studies using the same binning categories.

CONCLUSION

The majority of studies suggest that athletes are at greater risk of sustaining a time-loss injury when the ACWR is higher relative to a lower or moderate ACWR. The heterogenous methodological approaches not only reflect the wide range of sports studied and the differing demands of these activities, but also limit the strength of recommendations.

PROSPERO REGISTRATION NUMBER

CRD42017067585.

A Cherry, Ripe for Picking: The Relationship Between the Acute-Chronic Workload Ratio and Health Problems

OBJECTIVE

To investigate whether the relationship between the acute-chronic workload ratio (ACWR) and health problems varies when different methodological approaches are used to quantify it.

DESIGN

Prospective cohort study.

METHODS

An online questionnaire was used to collect daily health and training information from 86 elite youth footballers for 105 days. The relationship between players' training load and health was analyzed using a range of different definitions of ACWR and health problems. We used 21-day and 28-day chronic periods, coupled and uncoupled calculations, and the exponentially weighted moving average and rolling average. Acute-chronic workload ratio data were categorized as low, medium, or high, using predefined categories and z scores. We compared medium to high, medium to low, and low to high categories. The outcome was defined in 3 ways: "all health problems," "all injuries," and "new noncontact injuries." We performed random-effects logistic regression analyses of all combinations, for a total of 108 analyses.

RESULTS

We recorded 6250 athlete-days and 196 health problems. Of the 108 analyses performed, 23 (21%) identified a statistically significant (P<.05) association between the ACWR and health problems. A greater proportion of significant associations were identified when using an exponentially weighted moving average (44% of analyses), when comparing low to high categories (33%), and when using the "all health problems" definition (33%).

CONCLUSION

The relationship between the ACWR and health problems was dependent on methodological approach. J Orthop Sports Phys Ther 2021;51(4):162-173. Epub 20 Jan 2021. doi:10.2519/jospt.2021.9893.

Injury Trends in Irish Amateur Rugby: An Epidemiological Comparison of Men and Women

Background:

Rugby union is a physically demanding sport that carries an inherent risk of injury. Despite being a popular and widely played team sport, little is known about injuries occurring across the male and female amateur game.

Purpose:

To establish and compare injury incidence, nature, and severity in male and female Irish amateur rugby union.

Study Design:

Prospective cohort study.

Level of Evidence:

Level 3.

Methods:

Data were collected prospectively from 25 male teams (959 players) and 8 female teams (234 players) over 2 full seasons. Both time-loss (24-hour time-loss injury definition) and non-time-loss match injury reports were collected, alongside match exposure data.

Results:

Time-loss match injury incidence rates were 49.1/1000 and 35.6/1000 player-hours for male and female players, respectively. Concussion and ankle ligament sprains were the most common diagnoses for male (5.6/1000 and 4.4/1000 player-hours, respectively) and female players (5.5/1000 and 3.9/1000 player-hours, respectively). Anterior cruciate ligament injuries presented the highest injury burden for male and female players with 200.3 and 307.2 days of absence per 1000 player-hours, respectively. In female players, 83% of noncontact injuries occurred in the fourth quarter of match play.

Conclusion:

While female players had a lower overall injury incidence rate compared with male players, concussion and ankle ligament injuries were the most common injuries in both cohorts. In female players, a high rate of noncontact injuries in the second half points to the need for strength and conditioning training programs to reduce fatigue-related injuries.

Clinical Relevance:

Establishing the incidence and burden of rugby-related injuries is an essential step in minimizing injury risk. This epidemiological information will aid the development of future reduction strategies, including education and coaching strategies and strength and conditioning programs, informed by the most common injuries observed and the mechanism of injury.

The management of concussion in sport is not standardized. A systematic review

INTRODUCTION

Concussion is traumatic brain injury with associated tissue damage commonly produced by an indirect or direct head or facial trauma that can negatively impact an athletes' career and personal life. In this context, the importance on how to deal with a concussion has received attention from worldwide literature and has become a topic of enormous interest in the sports medicine arena.

OBJECTIVE

This systematic review aimed to investigate how sports-related concussion is being managed regarding athletic injuries, athletes' age, clinical signs of concussion, adopted questionnaires, as well as decision making in sports medicine.

METHODS

A systematic review of the literature was performed searching 10 electronic databases with no limitations for year of publication up to December 2019. The search terms used were: Brain Concussion, Athletes, Sports Medicine, Athletic Injuries, Clinical Decision-Making, and Decision Making. The articles were considered eligible when the studies related to populations of regular sports practitioners, professional or recreational, of any age; sports injury; articles reporting concussion evaluation in at least 30 athletes; and articles published in English, French, Portuguese, Italian. We excluded systematic review articles, reviews, editorials, sport-unrelated concussion, no questionnaire application, approaching retired athletes, consensus statement letters, author's reply to editorials, synopsis, and abstracts.

RESULTS

The parameters adopted for decision-making and management were broadly variable and were based on a variety of clinical signs or scoring outcomes from a myriad of questionnaires with little consistency in protocol or management guidelines, which could guide the average clinician.

CONCLUSION

This systematic review provides current evidence that post-concussion management in sports medicine has yet to accomplish a standardized protocol that clinicians could use to optimally care for athletes. The extensive number of manuscripts and studies addressing the topic confirms that sports-related concussion in the pediatric and adolescent population has come to the forefront in the sports medicine field.

Physical fitness changes among amateur soccer players: effects of the pre-season period

Study aim: To assess changes in physical fitness of amateur soccer players after a pre-season training period and baseline fitness dependencies.

Material and methods: Twenty-one amateur soccer players were assessed during the pre-season. The following physical variables were assessed before and after a two-month pre-season training period: (i) cardiorespiratory fitness, (ii) strength and power, and (iii) change of direction (COD).

Results: Significant decreases were found for countermovement jump (CMJ) (p < 0.001; d = 1.161), drop jump (DJ) (p = 0.014; d = 0.958), and horizontal jump (HJ) (p = 0.042; d = 0.640), while no significant changes were found for the overall variables from the beginning to the end of pre-season. Fit players revealed significant decreases for CMJ (p = 0.002; d = –2.495), DJ (p = 0.004; d = –1.760), HJ (p = 0.028; d = –1.005), COD deficit (p = 0.034; d = 1.013), and maximal aerobic speed (MAS) (p = 0.026; d = –4.053). No significant changes were found for unfit players.

Conclusions: Amateur soccer coaches should consider assessing physical qualities at the beginning of pre-season and use the free-of-charge monitoring tools such as session-rate of perceived exertion (s-RPE) during the training process.

Training Load and Injury: Causal Pathways and Future Directions

Causal pathways between training loads and the mechanisms of tissue damage and athletic injury are poorly understood. Here, the relation between specific training load measures and metrics, and causal pathways of gradual onset and traumatic injury are examined. Currently, a wide variety of internal and external training load measures and metrics exist, with many of these being commonly utilized to evaluate injury risk. These measures and metrics can conceptually be related to athletic injury through the mechanical load-response pathway, the psycho-physiological load-response pathway, or both. However, the contributions of these pathways to injury vary. Importantly, tissue fatigue damage and trauma through the mechanical load-response pathway is poorly understood. Furthermore, considerable challenges in quantifying this pathway exist within applied settings, evidenced by a notable absence of validation between current training load measures and tissue-level mechanical loads. Within this context, the accurate quantification of mechanical loads holds considerable importance for the estimation of tissue damage and the development of more thorough understandings of injury risk. Despite internal load measures of psycho-physiological load speculatively being conceptually linked to athletic injury through training intensity and the effects of psycho-physiological fatigue, these measures are likely too far removed from injury causation to provide meaningful, reliable relationships with injury. Finally, we used a common training load metric as a case study to show how the absence of a sound conceptual rationale and spurious links to causal mechanisms can disclose the weaknesses of candidate measures as tools for altering the likelihood of injuries, aiding the future development of more refined injury risk assessment methods.

Sports in time of COVID-19: Impact of the lockdown on team activity

The COVID-19 pandemic has affected many sectors of our global society since its detection in Wuhan in December 2019, and team sports have been no stranger to this reality. This special article presents a review of the literature exposing the dangers for athletes of this virus, reporting the effects of the pandemic on competitive sport, and making evidence-based recommendations to avoid the consequences of detraining in confined athletes. Furthermore, we present the results of a survey with 361 answers computed from coaches and different staff members from 26 different countries, representing the activity of more than 4500 athletes from all over the world. The aim was to know more teams’ activity during this cessation period. Finally, the article outlines recommendations based on the answers to help teams if a second outbreak of the virus forces massive confinements again, guiding a safe return to sport at any competitive level.

"Road to Rio": A Case Study of Workload Periodization Strategy in Rugby-7s During an Olympic Season

The objective of this manuscript was to examine the periodization strategy of an international Rugby-7s team during an Olympic season. Training load data were collected in 14 elite male players over a 48-week period during the 2015–2016 Olympic season. The season consisted of 3 macrocycles including: preseason (12-weak duration), in-season (25-weak) fragmented into four 4–7 weeks mesocycles (In-1–4) and the final preparation for the Rio 2016 Olympic Games (Olympic preparation, 11-weak). External training load (TL) such as the total distance (TD), the high-intensity distance (HID) and the number of accelerations performed, was monitored in training and competition over the entire duration of the season using a global positioning system (GPS) devices. The rating of perceived exertion (RPE) was multiplied by the session duration (min) to provide an internal TL (session-RPE) value for all training sessions and competitions. The Olympic preparation may enable planning of higher external TL compared to the preseason (TD, 21 ± 13%, moderate; total accelerations, 27 ± 4%, moderate) whereas no difference was observed for internal TL values between these two periods. High-intensity distance (HID) and internal TL (session-RPE) were lower (−11.0 ± 7.8%, small and −38 ± 3%, moderate, respectively) during the in-season compared to preseason. Internal TL, TD as well as HID were lower in the third in-season mesocycle (In-3) compared with the first in-season mesocycle (In-1) (−25 ± 12%, moderate; −32 ± 4%, moderate; −49 ± 8%, moderate, respectively). The staff managed the workload considering the in-season as the main part of the “Road to Rio.” The strategy to reduce the workload at the middle of the season and to induce weeks of regeneration at the end of the in-season was highlighted by the training availability of 100% of the squad at the beginning of the Olympic preparation. The workload periodization strategy of an Olympic season differs from the strategy previously described during a non-Olympic season.

Relationship Between Preseason Training Load, Match Performance, and Match Activities in Professional Rugby League

Crang, ZL, Hewitt, A, Scott, TJ, Kelly, VG, and Johnston, RD. Relationship between pre-season training load, match performance and match activities in professional rugby league. J Strength Cond Res XX(X): 000-000, 2020-This study aimed to establish the relationship between preseason training loads, technical match performance, and physical match activities in rugby league. Twenty-two professional rugby league players (age: 24.7 ± 4.0 years; height: 184.3 ± 4.7 cm; and body mass: 101.1 ± 9.9 kg) participated in the study. Training loads and physical match activities were monitored using global positioning systems. Total distance (m), high-speed running distance (VT1IFT; distance covered above estimated first ventilatory threshold [≥68% of 30-15 intermittent fitness test]) and total session rating of perceived exertion from all field-based (32.5 ± 8.5) and gym-based sessions (39.1 ± 12.5) were used to quantify preseason loads. Physical match activities were measured as total and high-speed running distance relative to individual playing time, whereas technical match activities and performance scores were used to evaluate individual match performance. To examine the relationship between physical match activities, technical performance, and preseason load, Pearson's correlation coefficients were quantified for each in-season game before performing a Fisher Z Transformation. Preseason high-speed running distance was positively associated with high-speed match activities (r = 0.34-0.51), whereas negatively associated with technical performance scores (r = -0.51 to -0.35) and hit up m·min of match-play (r = -0.30 to -0.17). It seems high speed running performed in the preseason period positively influences in-season physical match activity profiles, however, are unlikely to positively impact technical match performance.

THE GAP BETWEEN RESEARCH AND CLINICAL PRACTICE FOR INJURY PREVENTION IN ELITE SPORT: A CLINICAL COMMENTARY

As clinicians strive to apply evidence-based principles, team-based practitioners have identified a large gap as it relates to published research, ideal applications of evidence-based practice, and actual clinical practice related to injury prevention in elite sport within the United States. For rehabilitation professionals, especially those intimately involved in the research of injury prevention, the solution often seems quite clear and defined. However, preventing injury by implementing the latest recommendation from the most recent prospective study on the using the FIFA 11 + warm-up, a Copenhagen Adduction exercise, or a plyometric drill with elite athletes may not be as effective as was seen among the cohort used in the study. In addition to extrapolating research, clinicians face additional challenges such as variance among professions, schedule density, and off-season contacts with athletes. There is an inherent difficulty in the application of research to practice in elite sport as it relies on the teamwork of not only the practitioner and athlete, but the entire sporting organizational structure and those involved in athlete participation. The purpose of this clinical commentary is to explore the difficulty with application of research in clinical practice and to discuss potential strategies for improving carry over from research to clinical practice.

Workload a-WEAR-ness: Monitoring Workload in Team Sports With Wearable Technology. A Scoping Review

OBJECTIVES

To (1) identify the wearable devices and associated metrics used to monitor workload and assess injury risk, (2) describe the situations in which workload was monitored using wearable technology (including sports, purpose of the analysis, location and duration of monitoring, and athlete characteristics), and (3) evaluate the quality of evidence that workload monitoring can inform injury prevention.

DESIGN

Scoping review.

LITERATURE SEARCH

We searched the CINAHL, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Embase, HealthSTAR, MEDLINE, PsycINFO, SPORTDiscus, and Web of Science databases.

STUDY SELECTION CRITERIA

We included all studies that used wearable devices (eg, heart rate monitor, inertial measurement units, global positioning system) to monitor athlete workload in a team sport setting.

DATA SYNTHESIS

We provided visualizations that represented the workload metrics reported, sensors used, sports investigated, athlete characteristics, and the duration of monitoring.

RESULTS

The 407 included studies focused on team ball sports (67% soccer, rugby, or Australian football), male athletes (81% of studies), elite or professional level of competition (74% of studies), and young adults (69% of studies included athletes aged between 20 and 28 years). Thirty-six studies of 7 sports investigated the association between workload measured with wearable devices and injury.

CONCLUSION

Distance-based metrics derived from global positioning system units were common for monitoring workload and are frequently used to assess injury risk. Workload monitoring studies have focused on specific populations (eg, elite male soccer players in Europe and elite male rugby and Australian football players in Oceania). Different injury definitions and reported workload metrics and poor study quality impeded conclusions regarding the relationship between workload and injury. J Orthop Sports Phys Ther 2020;50(10):549-563. doi:10.2519/jospt.2020.9753.

The Training-Performance Puzzle: How Can the Past Inform Future Training Directions?

Over the past 20 years, research on the training-load-injury relationship has grown exponentially. With the benefit of more data, our understanding of the training-performance puzzle has improved. What were we thinking 20 years ago, and how has our thinking changed over time? Although early investigators attributed overuse injuries to excessive training loads, it has become clear that rapid spikes in training load, above what an athlete is accustomed, explain (at least in part) a large proportion of injuries. In this respect, it appears that overuse injuries may arise from athletes being underprepared for the load they are about to perform. However, a question of interest to both athletic trainers (ATs) and researchers is why some athletes sustain injury at low training loads, while others can tolerate much greater training loads? A higher chronic training load and well-developed aerobic fitness and lower body strength appear to moderate the training-injury relationship and provide a protective effect against spikes in load. The training-performance puzzle is complex and dynamic-at any given time, multiple inputs to injury and performance exist. The challenge facing researchers is obtaining large enough longitudinal data sets to capture the time-varying nature of physiological and musculoskeletal capacities and training-load data to adequately inform injury-prevention efforts. The training-performance puzzle can be solved, but it will take collaboration between researchers and clinicians as well as an understanding that efficacy (ie, how training load affects performance and injury in an idealized or controlled setting) does not equate to effectiveness (ie, how training load affects performance and injury in the real-world setting, where many variables cannot be controlled).

Global Positioning System-Derived Workload Metrics and Injury Risk in Team-Based Field Sports: A Systematic Review

OBJECTIVE

To evaluate the current literature regarding the utility of global positioning system (GPS)-derived workload metrics in determining musculoskeletal injury risk in team-based field-sport athletes.

DATA SOURCES

PubMed entries from January 2009 through May 2019 were searched using terms related to GPS, player workload, injury risk, and team-based field sports.

STUDY SELECTION

Only studies that used GPS metrics and had injury as the main outcome variable were included.

DATA EXTRACTION

Total distance, high-speed running, and acute : chronic workload ratios were the most common GPS metrics analyzed, with the most frequent sports being soccer, rugby, and Australian rules football.

DATA SYNTHESIS

Many distinct workload metrics were associated with increased injury risk in individual studies performed in particular sport circumstances; however, the body of evidence was inconclusive as to whether any specific metrics could consistently predict injury risk across multiple team-based field sports.

CONCLUSIONS

Our results were inconclusive in determining if any GPS-derived workload metrics were associated with an increased injury risk. This conclusion is due to a myriad of factors, including differences in injury definitions, workload metrics, and statistical analyses across individual studies.

Is There a Relationship Between Workload and Occurrence of Back Pain and Back Injuries in Athletes?

The back is subjected to a great deal of strain in many sports. Up to 20% of all sports injuries involve an injury to the lower back or neck. Repetitive or high impact loads (e.g., running, gymnastics, skiing) and weight loading (e.g., weightlifting) affect the lower back. Rotation of the torso (e.g., golf, tennis) causes damage to both, the lumbar and thoracic spine. The cervical spine is most commonly injured in contact sports (e.g., boxing, football). One of the factors that increases the odds of injuries in athletes is excessive and rapid increases in training loads. In spite of currently emerging evidence on this issue, little is known about the balance between physiological loading on the spine and athletic performance, versus overloading and back pain and/or injury in athletes. This scoping review aims (i) to map the literature that addresses the association between the training load and the occurrence of back pain and/or injury, especially between the Acute:Chronic Workload Ratio (ACWR) and back problems in athletes of individual and team sports, and (ii) to identify gaps in existing literature and propose future research on this topic. A literature search of six electronic databases (i.e., MEDLINE, PubMed, Web of Science, SCOPUS, SportDiscus, and CINAHL) was conducted. A total of 48 research articles met the inclusion criteria. Findings identified that fatigue of the trunk muscles induced by excessive loading of the spine is one of the sources of back problems in athletes. In particular, high training volume and repetitive motions are responsible for the high prevalence rates. The most influential are biomechanical and physiological variations underlying the spine, though stress-related psychological factors should also be considered. However, limited evidence exists on the relationship between the ACWR and back pain or non-contact back injuries in athletes from individual and team sports. This may be due to insufficiently specified the acute and chronic time window that varies according to sport-specific schedule of competition and training. More research is therefore warranted to elucidate whether ACWR, among other factors, is able to identify workloads that could increase the risk of back problems in athletes.

The use of GPS and inertial devices for player monitoring in team sports: A review of current and future applications

Player-worn devices, combining global positioning system and inertial monitors, are being used increasingly by professional sports teams. Recent interest focusses on using the data generated to track trainingload and whether this may lead to more effective training prescription with better management of injury risk. The aim of this review is to summarize the development and current use of this technology alongside proposed future applications. PubMed and Medline searches (2000-2017) identified all relevant studies involving use in team sports or comparative studies with other accepted methods. Our review determined that the latest devices are valid and reliably track activity levels. This technology is both accurate and more efficient than previous methods. Furthermore, recent research has shown that measurable changes in trainingload (the acute-to-chronic load ratio) are related to injury risk. However, results remain very sport specific and generalization must be done with caution. Future uses may include injury-prevention strategies and return-to-play judgement.

Are Elite Soccer Teams' Preseason Training Sessions Associated With Fewer In-Season Injuries? A 15-Year Analysis From the Union of European Football Associations (UEFA) Elite Club Injury Study

BACKGROUND

Preseason training develops players' physical capacities and prepares them for the demands of the competitive season. In rugby, Australian football, and American football, preseason training may protect elite players against in-season injury. However, no study has evaluated this relationship at the team level in elite soccer.

PURPOSE/HYPOTHESIS

The aim of this study was to investigate whether the number of preseason training sessions completed by elite soccer teams was associated with team injury rates and player availability during the competitive season. It was hypothesized that elite soccer teams who participate in more preseason training will sustain fewer injuries during the competitive season.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

We used the Union of European Football Associations (UEFA) injury dataset to analyze 44 teams for up to 15 seasons (total, 244 team-seasons). Separate linear regression models examined the association between the number of team preseason training sessions and 5 in-season injury measures. Injury-related problems per team were quantified by totals of the following: (1) injury burden, (2) severe injury incidence, (3) training attendance, (4) match availability, and (5) injury incidence.

RESULTS

Teams averaged 30 preseason training sessions (range, 10-51). A greater number of preseason training sessions was associated with less injury load during the competitive season in 4 out of 5 injury-related measures. Our linear regression models revealed that for every 10 additional preseason training sessions that the team performed, the in-season injury burden was 22 layoff days lower per 1000 hours (P = .002), the severe injury incidence was 0.18 severe injuries lower per 1000 hours (P = .015), the training attendance was 1.4 percentage points greater (P = .014), and the match availability was 1.0 percentage points greater (P = .042). As model fits were relatively low (adjusted R² = 1.3%-3.2%), several factors that contribute to in-season injury outcomes were unaccounted for.

CONCLUSION

Teams that performed a greater number of preseason training sessions had "healthier" in-season periods. Many other factors also contribute to in-season injury rates. Understanding the benefit of preseason training on in-season injury patterns may inform sport teams' planning and preparation.

Injury epidemiology in Australian male professional soccer

OBJECTIVES

To describe the injury epidemiology of the Australian male professional soccer league (A-League) over 6 consecutive seasons.

DESIGN

Prospective observational cohort study.

METHODS

Match-loss injury data was collected from each A-League club (n=10) for each competition match (n=27/season) over 6 seasons (2012/13-2017/18). Injuries were collected weekly through a standardised protocol and were classified by setting, mechanism, severity, the type and location on the body. Generalised Linear Models were used to estimate the injury incidences (injury/round/season), whilst rate ratios were reported for total injuries and within abovementioned injury classifications.

RESULTS

Overall injury incidence was not significantly different ranging from 4.8 (95%CI:4.1-5.8) to 6.7 (95%CI:5.8-7.8) between seasons 2012/13 to 2017/18 (p>0.05). Match injuries remained stable whilst training injuries decreased across the 6 seasons (exp(β) 0.59[95%CI:0.36-1.0]; p=0.04). Respectively, contact and non-contact injuries were not significantly different across the 6 seasons, although non-contact injuries were more common than contact injuries (p>0.05). Mild severity injuries decreased (exp(β) 0.64 [95%CI:0.4-0.9];p=0.02), whilst moderate severity injuries increased (exp(β) 1.7 [95%CI:1.0-2.8];p=0.04) in season 2017/18 compared to 2012/13. The most common injuries were at thigh (23-36%), of which the majority were hamstring injuries (54%-65%) of muscle/tendon type (50-60% of total injuries/season). Injuries remained stable across the seasons by type and location (p>0.05 and p>0.05, respectively).

CONCLUSIONS

Injury rates, mechanisms, locations and types have remained relatively stable over recent seasons of the A-League. Current Australian professional soccer league medical practices may have contributed to the stability of injury rates.

Does Overexertion Correlate With Increased Injury? The Relationship Between Player Workload and Soft Tissue Injury in Professional American Football Players Using Wearable Technology

BACKGROUND

The relationship of training load to injury using wearable technology has not been investigated in professional American football players. The primary objective of this study was to determine the correlation between player workload and soft tissue injury over the course of a football season utilizing wearable global positioning system (GPS) technology.

HYPOTHESIS

Increased training load is associated with a higher incidence of soft tissue injuries.

STUDY DESIGN

Case-control study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Player workloads were assessed during preseason and regular-season practice sessions using GPS tracking and triaxial accelerometry from 2014 to 2016. Soft tissue injuries were recorded during each season. Player workload during the week of injury (acute) and average weekly workload during the 4 weeks (chronic) prior to injury were determined for each injury and in uninjured position-matched controls during the same week. A matched-pairs t test was used to determine differences in player workload. Subgroup analysis was also conducted to determine whether observed effects were confounded by training period and type of injury.

RESULTS

In total, 136 lower extremity injuries were recorded. Of the recorded injuries, 101 injuries with complete GPS and clinical data were included in the analysis. Injuries were associated with greater increases in workload during the week of injury over the prior month when compared with uninjured controls. Injured players saw a 111% (95% CI, 66%-156%) increase in workload whereas uninjured players saw a 73% (95% CI, 34%-112%) increase in workload during the week of injury (P = 0.032). Individuals who had an acute to chronic workload ratio higher than 1.6 were 1.5 times more likely to sustain an injury relative to time- and position-matched controls (64.6% vs 43.1%; P = 0.004).

CONCLUSION

Soft tissue injuries in professional football players were associated with sudden increases in training load over the course of a month. This effect seems to be especially pronounced during the preseason when player workloads are generally higher. These results suggest that a gradual increase of training intensity is a potential method to reduce the risk of soft tissue injury.

CLINICAL RELEVANCE

Preseason versus regular-season specific training programs monitored with wearable technology may assist team athletic training and medical staff in developing programs to optimize player performance.

Session Availability as a Result of Prior Injury Impacts the Risk of Subsequent Non-contact Lower Limb Injury in Elite Male Australian Footballers

Prior injury is a commonly identified risk factor for subsequent injury. However, a binary approach to classifying prior injury (i.e., yes/no) is commonly implemented and may constrain scientific findings, as it is possible that variations in the amount of time lost due to an injury will impact subsequent injury risk to differing degrees. Accordingly, this study investigated whether session availability, a surrogate marker of prior injury, influenced the risk of subsequent non-contact lower limb injury in Australian footballers. Data were collected from 62 male elite Australian footballers throughout the 2015, 2016, and 2017 Australian Football League seasons. Each athlete's participation status (i.e., full or missed/modified) and any injuries that occurred during training sessions/matches were recorded. As the focus of the current study was prior injury, any training sessions/matches that were missed due to reasons other than an injury (e.g., load management, illness and personal reasons) were removed from the data prior to all analyses. For every Monday during the in-season periods, session availability (%) in the prior 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, and 84 days was determined as the number of training sessions/matches fully completed (injury free) relative to the number of training sessions/matches possible in each window. Each variable was modeled using logistic regression to determine its impact on subsequent injury risk. Throughout the study period, 173 non-contact lower limb injuries that resulted in at least one missed/modified training session or match during the in-season periods occurred. Greater availability in the prior 7 days increased injury probabilities by up to 4.4%. The impact of session availability on subsequent injury risk diminished with expanding windows (i.e., availability in the prior 14 days through to the prior 84 days). Lesser availability in the prior 84 days increased injury probabilities by up to 14.1%, only when coupled with greater availability in the prior 7 days. Session availability may provide an informative marker of the impact of prior injury on subsequent injury risk and can be used by coaches and clinicians to guide the progression of training, particularly for athletes that are returning from long periods of injury.

Tendon and Ligament Injuries in Elite Rugby: The Potential Genetic Influence

This article reviews tendon and ligament injury incidence and severity within elite rugby union and rugby league. Furthermore, it discusses the biological makeup of tendons and ligaments and how genetic variation may influence this and predisposition to injury. Elite rugby has one of the highest reported injury incidences of any professional sport. This is likely due to a combination of well-established injury surveillance systems and the characteristics of the game, whereby high-impact body contact frequently occurs, in addition to the high intensity, multispeed and multidirectional nature of play. Some of the most severe of all these injuries are tendon and ligament/joint (non-bone), and therefore, potentially the most debilitating to a player and playing squad across a season or World Cup competition. The aetiology of these injuries is highly multi-factorial, with a growing body of evidence suggesting that some of the inter-individual variability in injury susceptibility may be due to genetic variation. However, little effort has been devoted to the study of genetic injury traits within rugby athletes. Due to a growing understanding of the molecular characteristics underpinning the aetiology of injury, investigating genetic variation within elite rugby is a viable and worthy proposition. Therefore, we propose several single nucleotide polymorphisms within candidate genes of interest; COL1A1, COL3A1, COL5A1, MIR608, MMP3, TIMP2, VEGFA, NID1 and COLGALT1 warrant further study within elite rugby and other invasion sports.

Comparison of Preseason and In-Season Practice and Game Loads in National Collegiate Athletic Association Division I Football Players

Wellman, AD, Coad, SC, Flynn, PJ, Siam, TK, and McLellan, CP. A Comparison of preseason and in-season practice and game loads in NCAA Division I football players. J Strength Cond Res 33(4): 1020-1027, 2019-The aim of this study was to quantify the individual practice and game loads throughout the National Collegiate Athletic Association (NCAA) Division I football season to determine whether significant differences exist between the practice loads associated with the preseason training camp and those undertaken during the in-season period. Thirty-one NCAA Division I football players were monitored using the global positioning system and triaxial accelerometer (IA) (MinimaxX S5; Catapult Innovations, Melbourne, Australia) during 22 preseason practices, 36 in-season practices, and 12 competitions. The season was divided into 4 distinct phases for data analysis: preseason week 1 (preseason 1), preseason week 2 (preseason 2), preseason week 3 (preseason 3), and 12 in-season weeks. Individual IA data sets represented players from every offensive and defensive position group Wide Receiver (WR: n = 5), Offensive Line (OL: n = 4), Running Back (RB: n = 4), Quarterback (QB: n = 2), Tight End (TE: n = 3), Defensive Line (DL: n = 4), Linebacker (LB: n = 4), Defensive Back (DB: n = 5). Data were set at the practice level, where an observation for each player's maximum player load (PLMax) or mean player load (PLMean) from each training camp phase was referenced against each player's respective PL from each game, Tuesday, Wednesday, or Thursday practice session. Notable results included significantly (p ≤ 0.05) greater PLMax values attributed to preseason 1 compared with PL resulting from all in-season practices, and significantly (p ≤ 0.05) higher cumulative PL reported for preseason 1, 2, and 3 compared with every in-season week. Data from this study augment our understanding of the practice demands experienced by NCAA Division I college football players, and provide scope for the improvement of preseason practice design and physical conditioning strategies for coaches seeking to optimize performance.