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

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.

Limited Return to Preinjury Performance in NCAA Division I American Football Players With Hamstring Injuries

Background

Hamstring strains are common among elite athletes, but their effect on return to the same level of play in American football has been incompletely characterized.

Purpose

Data on National Collegiate Athletics Association Division I college football players with acute hamstring strains were gathered to identify the effects these injuries have on both return to play and athletic performance regarding velocity, workload, and acceleration.

Study Design

Case Series; Level of evidence, 4.

Methods

Injury data for a single Division I football team were prospectively recorded over a 4-year period. Players wore global navigation satellite system and local positioning system (GNSS/LPS) devices to record movement data in practices and games. The practice and game data were cross-referenced to evaluate players with isolated acute hamstring strains. Comparisons were made regarding players' pre- and postinjury ability to maintain high velocity (>12 mph [19.3 kph]), maximal velocity, triaxial acceleration, and inertial movement analysis (IMA). There were 58 hamstring injuries in 44 players, of which 25 injuries from 20 players had GNSS/LPS data.

Results

Players were able to return to play from all 25 injury incidences at a mean of 9.2 days. At the final mean follow-up of 425 days, only 4 players had reached preinjury function in all measurements; 12 players were able to return in 2 of the 4 metrics; and only 8 players reached their preinjury ability to maintain high velocity. For those who did not achieve this metric, there was a significant difference between pre- and postinjury values (722 vs 442 m; P = .016). A total of 14 players were able to regain their IMA. Players who returned to prior velocity or acceleration metrics did so at a mean of 163 days across all metrics.

Conclusion

While players may be able to return to play after hamstring strain, many players do not reach preinjury levels of acceleration or velocity, even after 13.5 months. Further studies are needed to confirm these findings, assess clinical relevance on imaging performance, and improve hamstring injury prevention and rehabilitation.

Wearable electronic devices in parasports: A focused review on para athlete classification

Wearable electronic devices are being used to evaluate movement patterns, track workload, prevent injuries, and optimize performance in athletes. Para athletes have unique characteristics to consider separately from the general population. One such difference in competitive parasports includes consideration of athlete classification systems. These sport-specific classification systems consider athletes' eligible medical conditions that lead to permanent physical, visual, and/or intellectual impairments and objectively evaluate the impact of their impairments on sport functions. Para athletes are assigned sport classes and compete with athletes of similar functional levels. This promotes equitable opportunities to compete while minimizing the effect their impairment has on their sport performance. With recent reports of misrepresentation or incorrect and unfair classification providing unfair advantages to some athletes, parasports classification has been controversial. Having an objective, evidence-based, and fair classification system in parasports is critical to maintain the integrity of parasports competition. Wearable electronic devices have potential to provide more objective analysis of movement patterns in para athletes to assist in sport classification. This review identifies and analyzes the available literature on wearable electronic technology and its role in parasports classification. A comprehensive PubMed and Google Scholar search identified six articles included in this review. These studies used inertial sensors, motion capture systems, or surface electromyography in wheelchair basketball, rugby, tennis, sit skiing, and boccia. This review identifies the potential value of wearable electronic devices to assist in parasports classification. Additional studies are needed to create standardized protocols for each sport and sensor type.

Testing variations between starters and substitute players in terms of total distance, high-speed running, and sprinting distance: a descriptive study on professional male soccer players

The purpose of this study was three-fold: (i) to compare total distance, high-speed running (HSR) distance, and sprint distance covered per 5-minute epoch by players acting as both starters and substitutes; (ii) to compare the locomotor demands between the moments the players entered the match (45-60, 60-75 and 75-90 minutes); and (iii) to compare the locomotor demands of the players between the variations of the within- and between-playing positions. Twenty-one male professional soccer players competing in the Professional Premier League of one of the European countries were observed over sixteen official matches. The players were monitored during all matches using a Global Navigation Satellite System. The measures collected were total distance (TD; m), distance in HSR, sprint distance, HSR, and sprint counts. Considering the comparisons between the splits over the second half of match play, a significant difference between the starters and the substitutes was observed only for sprint distance in the 90-95 minute split (Z = -2.023; p = 0.043). Moreover, no substantial differences were found between the moment the substitute player entered the match regarding total distance (H = 2.650; p = 0.266), HSR distance (H = 1.738; p = 0.419), and sprint distance (H = 0.048; p = 0.976). However, the comparison of between-playing positions revealed considerable differences in total distance (H = 29.246; p < 0.001), and HSR distance (H = 12.153; p = 0.002) covered by the players acting as starters. In contrast, for substitute players, such differences were reported in HSR distance (H = 27.892; p < 0.001) and sprint distance (H = 15.879; p < 0.001). In conclusion, this study suggests that acting as a starter or a substitute does not significantly affect the intensity of effort except during the last periods of match play. However, the contextual factor of performing in a specific playing position plays a significant role both for starters and substitutes.

Editorial Commentary: Load Management Is Essential to Prevent Season-Ending Injuries in the National Basketball Association

Each season, National Basketball Association (NBA) athletes subject themselves to a physical season including a minimum of 82 games, intense travel, participation during holidays, innumerable training sessions, and for some, playoffs continuing into June. Intensity and fatigue may contribute to a high rate of injuries, and recent literature has suggested that primary risk factors for season-ending injuries are minutes played per game and later season games. Scheduled periods of rest, or load management, reduce the physiological load a player endures during a grueling season. Disadvantages of load management may include decrements in individual skill, team competitiveness, and financial issues, including disappointed fans. Thus, in 2023, the NBA instituted the Player Participation Policy (PPP) placing stipulations on load management by asking teams to balance player rest between home and away games and to refrain from long-term shutdowns of player participation for nonmedical reasons. From a medical standpoint, safeguarding athlete health is of paramount importance. Managing the workload of NBA players may have numerous player benefits and must be achieved while mitigating the disadvantages.

Wearable Devices and Digital Biomarkers for Optimizing Training Tolerances and Athlete Performance: A Case Study of a National Collegiate Athletic Association Division III Soccer Team over a One-Year Period

Wearable devices in sports have been used at the professional and higher collegiate levels, but not much research has been conducted at lower collegiate division levels. The objective of this retrospective study was to gather big data using the Catapult wearable technology, develop an algorithm for musculoskeletal modeling, and longitudinally determine the workloads of male college soccer (football) athletes at the Division III (DIII) level over the course of a 12-week season. The results showed that over the course of a season, (1) the average match workload (432 ± 47.7) was 1.5× greater than the average training workload (252.9 ± 23.3) for all positions, (2) the forward position showed the lowest workloads throughout the season, and (3) the highest mean workload was in week 8 (370.1 ± 177.2), while the lowest was in week 4 (219.1 ± 26.4). These results provide the impetus to enable the interoperability of data gathered from wearable devices into data management systems for optimizing performance and health.

The Fundamentals and Applications of Wearable Sensor Devices in Sports Medicine: A Scoping Review

PURPOSE

To (1) characterize the various forms of wearable sensor devices (WSDs) and (2) review the peer-reviewed literature of applied wearable technology within sports medicine.

METHODS

A systematic search of PubMed and EMBASE databases, from inception through 2023, was conducted to identify eligible studies using WSDs within sports medicine. Data extraction was performed of study demographics and sensor specifications. Included studies were categorized by application: athletic training, rehabilitation, and research.

RESULTS

In total, 43 studies met criteria for inclusion in this review. Forms of WSDs include pedometers, accelerometers, encoders (consisting of magnetometers and gyroscopes), force sensors, global positioning system trackers, and inertial measurement units. Outcome metrics include step counts; gait, limb motion, and angular positioning; foot and skin pressure; change of direction and inclination, including analysis of both body parts and athletes on a field; displacement and velocity of body segments and joints; heart rate; plethysmography; sport-specific kinematics; range of motion, symmetry, and alignment; head impact; sleep; throwing biomechanics; and kinetic and spatiotemporal running metrics. WSDs are used in athletic training to assess sport-specific biomechanics and workload with a goal of injury prevention and training optimization, as well as for rehabilitation monitoring and research such as for risk predicting and aiding diagnosis.

CONCLUSIONS

WSDs enable real-time monitoring of human performance across a variety of implementations and settings, allowing collection of metrics otherwise not achievable. WSDs are powerful tools with multiple applications within athletic training, patient rehabilitation, and orthopaedic and sports medicine research.

CLINICAL RELEVANCE

Wearable technology may represent the missing link to quantitatively addressing return to play and previous performance. WSDs are commercially available and portable adjuncts that allow clinicians, trainers, and individual athletes to monitor biomechanical parameters, workload, and recovery status to better contextualize personalized training, injury risk, and rehabilitation.

From data to action: a scoping review of wearable technologies and biomechanical assessments informing injury prevention strategies in sport

BACKGROUND

The purpose of this scoping review was to evaluate the current use of technologies in sports settings for training adaptation and injury prevention. The review aimed to map the existing literature, identify key concepts and themes, and highlight gaps in research, thus offering guidance for future studies.

METHODS

This study followed the guidelines of the PRISMA extension for scoping reviews and a search in four major databases was conducted.

RESULTS

A total of 21 studies were included. The findings highlighted the widespread use of various technologies, including wearable devices and force plates, to monitor athletes' performance and inform evidence-based decision-making in training and injury prevention. Variables such as Player Load, changes of direction, and acute chronic workload ratio were identified as key metrics in injury prediction.

CONCLUSIONS

This review uncovers a dynamic field of research in athlete injury prevention, emphasizing the extensive use of varied technologies. A key finding is the pivotal role of Player Load data, which offers nuanced insights for customizing training loads according to sport-specific demands, player positions, and the physical requirements of various activities. Additionally, the review sheds light on the utility of tools like force plates in assessing fatigue, aiding recovery, and steering injury rehabilitation, particularly in sports prone to knee and ankle injuries. These insights not only enhance our understanding of injury prevention but also provide a strategic direction for future research, aiming to boost athlete safety, performance, and career longevity.

Therapeutic Exercises and Modalities in Athletes With Acute Hamstring Injuries: A Systematic Review and Meta-analysis

CONTEXT

Hamstring strain is a common injury to the lower limbs. Early intervention in the acute phase aids with restoring hamstring function and prevents secondary related injury.

OBJECTIVE

To systematically review and summarize the effectiveness of exercise-based interventions combined with physical modalities currently used in athletes with acute hamstring injuries.

DATA SOURCES

Five databases (EMBASE, Medline, Cochrane Library, SPORTDiscus, and Web of Science) were searched from inception to July 2021.

STUDY SELECTION

A total of 4569 studies were screened. Nine randomized controlled trials (RCTs) on the effect of therapeutic exercise programs with and without physical agents in athletes with acute hamstring injuries were identified for meta-analysis.

STUDY DESIGN

Systematic review and meta-analysis.

LEVEL OF EVIDENCE

Level 1.

DATA EXTRACTION

The studies were screened, and the evidence was rated using the PEDro scale. Nine RCTs with PEDro scores ranging between 3 and 9 were included and extracted pain intensity, time to return to play (TTRTP), and reinjury rate in the study.

RESULTS

Loading exercises during extensive lengthening were shown to facilitate TTRTP at P < 0.0001 but did not prevent recurrence (P = 0.17), whereas strengthening with trunk stabilization and agility exercise did not reduce the duration of injury recurrence (P = 0.16), but significantly reduced the reinjury rate (P < 0.007) at a 12-month follow-up. The results of the stretching programs and solely physical modalities could not be pooled in the statistical analysis.

CONCLUSION

The meta-analysis indicated that a loading program helps athletes to return to sports on a timely basis. Although strengthening with trunk stabilization and agility exercise cannot significantly reduce recovery time, the program can prevent reinjury. The clinical effects of stretching programs and pure physical modality interventions could not be concluded in this study due to limited evidence.

PROSPERO REGISTRATION

CRD42020183035.

Wearable technology may assist in reducing jockeys' injuries if integrated into their safety vests: a qualitative study

While the term "safety vests" has been used to capture these products to reduce the potential for harm in jockeys under the Personal Protective Equipment (PPE) umbrella, much of the research in this area has focused on factors typically echoing health, well-being, physiological and cognitive function, and performance of horse riders with very little work about examining how its design may reduce the severity of jockeys' injuries. Due to the recent advances in technology and wearable sensors, the author considered a qualitative study focusing on the analysis of a real-life example involving end and co-dependent users in the design development of jockeys' safety vests. This little article offers an overview of the most popular jockeys' injuries, why there is a need for better protection, and also describes how data were collected and present a summary of the key findings to encourage future research in this field, aiming to create a new prototype. High-impact sports may potentially create severe injuries or deaths to athletes: thus, there is a strong faith in the application of wearable sensor data and data science to also enhance jockeys' safety vest performance.

Physiological and Biomechanical Monitoring in American Football Players: A Scoping Review

American football is the sport with the highest rates of concussion injuries. Biomedical engineering applications may support athletes in monitoring their injuries, evaluating the effectiveness of their equipment, and leading industrial research in this sport. This literature review aims to report on the applications of biomedical engineering research in American football, highlighting the main trends and gaps. The review followed the PRISMA guidelines and gathered a total of 1629 records from PubMed (n = 368), Web of Science (n = 665), and Scopus (n = 596). The records were analyzed, tabulated, and clustered in topics. In total, 112 studies were selected and divided by topic in the biomechanics of concussion (n = 55), biomechanics of footwear (n = 6), biomechanics of sport-related movements (n = 6), the aerodynamics of football and catch (n = 3), injury prediction (n = 8), heat monitoring of physiological parameters (n = 8), and monitoring of the training load (n = 25). The safety of players has fueled most of the research that has led to innovations in helmet and footwear design, as well as improvements in the understanding and prevention of injuries and heat monitoring. The other important motivator for research is the improvement of performance, which has led to the monitoring of training loads and catches, and studies on the aerodynamics of football. The main gaps found in the literature were regarding the monitoring of internal loads and the innovation of shoulder pads.

Injury rates remained elevated in the second National Football League season after the onset of the COVID-19 pandemic

Purpose

The purpose of this study is to compare the injury incidence of the 2018-2019 and 2020 National Football League (NFL) seasons with the 2021 season.

Methods

Publicly released NFL weekly injury reports were queried to identify players listed as "out" or placed on injured reserve (IR) for at least one game in the 2018-2021 seasons. Injuries were then categorized into upper extremity, lower extremity, spine/core, and head. Incidence per 1,000 athlete exposures were calculated for each season and proportions of injuries by position were calculated separately for the 2018-2019, 2020, and 2021 cohorts. Incidence rate ratios (IRR) were used to compare injury rates.

Results

Overall injury incidence in the 2021 NFL season increased compared to the pre-COVID-19 seasons (2018-2019) in all anatomical zones except for the upper extremity. [28.70 vs. 23.09 per 1,000 exposures, IRR 1.24 (95% CI: 1.14-1.36); p< 0.001]. The injury rate remained elevated and further increased in 2021 compared to the 2020 season for all anatomical zones other than the spine/core [28.70 vs. 21.64 per 1,000 exposures, IRR 1.33 (1.19-1.47); p< 0.001]. No significant difference existed during the early season (weeks 1-4); however, injury rates after week 4 increased in 2021 compared to both the 2018-2019 and 2020 seasons.

Conclusion

The injury incidence in the 2021 season remained elevated and increased further compared to both the 2018-2019 and 2020 seasons. Traumatic injuries resulting in missed games increased despite return to a more traditional season since the beginning of the COVID-19 pandemic. The injury rates significantly increased in mid- to late season.

Level of Evidence

III, cross-sectional study.

Effect of Vacuum Sealing Drainage on Soft Tissue Injury of Traumatic Fracture and Its Effect on Wound Recovery

Purpose

The current work is mainly to explore the effect of vacuum sealing drainage (VSD) on soft tissue injury (STI) caused by traumatic fractures (TFs) and its effect on wound recovery.

Methods

We first selected 90 patients with TF STI from May 2019 to May 2021, of which 40 patients (control group) received routine treatment, and the other 50 patients (observation group) were treated with VSD. The curative effect, rehabilitation (changing dressing frequency, healing time, and hospitalization time), pain severity, patient comfort, and complications were evaluated and compared.

Results

The observation group exhibited a higher total effective rate, lower dressing change frequency, complication rate, and shorter healing time and hospital stay than the control group, which are statistically significant. Statistically milder pain sensation and better patient comfort were also determined in the observation group.

Conclusions

VSD is effective and safe in the treatment of TF-induced sexually transmitted infections, which can effectively accelerate wound recovery while reducing pain sensation and improving patient comfort, with clinical promotion value.

Effect of COVID-19 on Injury Rates and Timing in the National Football League

Background:

The coronavirus 2019 (COVID-19) pandemic resulted in the cancellation of the 2020 National Football League (NFL) preseason and a decreased preseason roster size. The effect of this disruption on athlete injury rates is unknown.

Purpose/Hypothesis:

The purpose was to quantify the rates of anterior cruciate ligament (ACL), Achilles tendon, and hamstring tendon injuries in NFL players before and after the COVID-19 pandemic. We hypothesized that injury rates in the 2020 season would be higher than those seen prepandemic.

Study Design:

Descriptive epidemiology study. Level of evidence, 4.

Methods:

An online search using publicly available data was carried out to identify all NFL players who sustained an ACL, Achilles tendon, or hamstring tendon injury between April 1, 2017, and March 31, 2021. Data collected included player characteristics as well as career and season of injury workloads.

Results:

The number of Achilles tendon (27 vs 20; P = .024) and hamstring tendon (186 vs 149; P < .001) injuries, respectively, in the 2020 NFL season were significantly higher than the average of the 2017 to 2019 seasons. However, the number of ACL injuries sustained remained constant (43 vs 46; P = .175). More than half (52.9%) of ACL injuries in the 2017 to 2019 seasons occurred in the preseason, while most of the injuries (34.9%) in the 2020 season occurred in weeks 1 to 4. There was no player characteristic or career workload variable collected that was significantly different for players who sustained an ACL, Achilles tendon, or hamstring tendon injury in the 2020 NFL season compared with the 2017 to 2019 seasons.

Conclusion:

In the 2020 NFL season, the number of Achilles tendon and hamstring tendon injuries rose while the number of ACL injuries remained constant compared with the 2017 to 2019 seasons. Injuries that occurred during the first 4 games of the 2020 NFL season were consistent, with higher rates of injuries seen in the preseason in previous years.

The Use of Wearable Sensors for Preventing, Assessing, and Informing Recovery from Sport-Related Musculoskeletal Injuries: A Systematic Scoping Review

Wearable technologies are often indicated as tools that can enable the in-field collection of quantitative biomechanical data, unobtrusively, for extended periods of time, and with few spatial limitations. Despite many claims about their potential for impact in the area of injury prevention and management, there seems to be little attention to grounding this potential in biomechanical research linking quantities from wearables to musculoskeletal injuries, and to assessing the readiness of these biomechanical approaches for being implemented in real practice. We performed a systematic scoping review to characterise and critically analyse the state of the art of research using wearable technologies to study musculoskeletal injuries in sport from a biomechanical perspective. A total of 4952 articles were retrieved from the Web of Science, Scopus, and PubMed databases; 165 were included. Multiple study features-such as research design, scope, experimental settings, and applied context-were summarised and assessed. We also proposed an injury-research readiness classification tool to gauge the maturity of biomechanical approaches using wearables. Five main conclusions emerged from this review, which we used as a springboard to propose guidelines and good practices for future research and dissemination in the field.

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.

Increased Lower Extremity Injury Risk Associated With Player Load and Distance in Collegiate Women's Soccer

Background:

There is limited research regarding the impact of workload on injury risk specific to women’s soccer. Wearable global positioning system (GPS) units can track workload metrics such as total distance traveled and player load during games and training sessions. These metrics can be useful in predicting injury risk.

Purpose:

To examine the relationship between injury risk and player workload as collected from wearable GPS units in National Collegiate Athletic Association (NCAA) Division I women’s soccer players.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

Lower extremity injury incidence and GPS workload data (player load, total distance, and high-speed distance) for 65 NCAA Division I women’s soccer players were collected over 3 seasons. Accumulated 1-, 2-, 3-, and 4-week loads and acute-to-chronic workload ratios (ACWR) were classified into discrete ranges by z-scores. ACWR was calculated using rolling averages and exponentially weighted moving averages (EWMA) models. Binary logistic regression models were used to compare the 7:28 rolling average and EWMA ACWRs between injured and noninjured players for all GPS/accelerometer variables. The prior 1-, 2-, 3-, and 4-week accumulated loads for all GPS/accelerometer variables were compared between the injured and uninjured cohorts using 2-sample t tests.

Results:

There were a total of 53 lower extremity injuries that resulted in lost time recorded (5.76/1000 hours “on-legs” exposure time; 34 noncontact and 19 contact injuries). The prior 2-week (7242 vs 6613 m/s²; P = .02), 3-week (10,533 vs 9718 m/s²; P = .02), and 4-week (13,819 vs 12,892 m/s²; P = .04) accumulated player loads and 2-week (62.40 vs 57.25 km; P = .04), 3-week (90.97 vs 84.10 km; P = .03), and 4-week (119.31 vs 111.38 km; P = .05) accumulated total distances were significantly higher for injured players compared with noninjured players during the same time frames. There were no significant differences in player load, total distance, or high-speed distance ACWR between injured and noninjured players for both the rolling averages and EWMA calculations.

Conclusion:

Higher accumulated player load and total distance, but not ACWR, were associated with injury in women’s soccer players.

Physiological Monitoring Detected Changes During Women's Soccer Anterior Cruciate Ligament Injury

A growing number of studies utilizing wearable technologies are examining the influence of the autonomic nervous system (ANS) on intense training, recovery, and injury risk. Exercise biometric (EB) data were collected on collegiate, female soccer players during a preseason camp. One player sustained an anterior cruciate ligament (ACL) injury. Baseline anthropometric and EB data were compared to non-injured, position-matched teammates.

All players had similar baseline testing. The injured athlete had a higher body mass index (BMI) and slower vision reaction time (RT). On the day of her injury (DOI), relative percentage heart rate recovery (tHRR) between intense training sets was calculated. Relative percentage tHRR was much lower for the injured athlete, indicating reduced recovery between training sets immediately prior to the injury. Also on DOI, the injured athlete had a lower glomerular filtration rate (GFR).

In addition to BMI and RT differences, the lower relative percentage tHRR and GFR on the DOI observed for the injured athlete may reflect an imbalanced ANS recovery, and potentially to risk factors leading to her ACL injury.

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.

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).

Wearable Technology and Analytics as a Complementary Toolkit to Optimize Workload and to Reduce Injury Burden

Wearable sensors enable the real-time and non-invasive monitoring of biomechanical, physiological, or biochemical parameters pertinent to the performance of athletes. Sports medicine researchers compile datasets involving a multitude of parameters that can often be time consuming to analyze in order to create value in an expeditious and accurate manner. Machine learning and artificial intelligence models may aid in the clinical decision-making process for sports scientists, team physicians, and athletic trainers in translating the data acquired from wearable sensors to accurately and efficiently make decisions regarding the health, safety, and performance of athletes. This narrative review discusses the application of commercial sensors utilized by sports teams today and the emergence of descriptive analytics to monitor the internal and external workload, hydration status, sleep, cardiovascular health, and return-to-sport status of athletes. This review is written for those who are interested in the application of wearable sensor data and data science to enhance performance and reduce injury burden in athletes of all ages.

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.

Public Online Interest in Injuries Sustained by National Football League Quarterbacks

Purpose

To use Google search data to determine the public’s interest in learning about athletic injuries sustained by NFL quarterbacks and to investigate how long this interest persists after the injuries.

Methods

We identified starting NFL quarterbacks during the 2019–2020 season online and used the official NFL injury report to determine whether an injury had occurred to a quarterback. We used the Google Trends tool to analyze search trends around a quarterback’s injuries from July 22, 2019, to October 22, 2019. Google trends data was extracted as relative search volume over time. We then compared the results to the expected search forecast derived from an autoregressive integrated moving algorithm (ARIMA) model.

Results

All 6 injured quarterbacks were associated with increases (64% to 100%) in relative search volumes for terms related to their injury. Furthermore, the data showed a consistent increase in search engine activity around the injuries associated with NFL quarterbacks in the first 3 days, marking a particularly influential time frame for public engagement.

Conclusion

Our data show an increase in Google traffic surrounding the injuries of prominent NFL quarterbacks within the first 3 days following their injuries.

Clinical Relevance

Social media can provide a platform for patient education through increasing patient awareness and knowledge regarding athletic injuries.

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.

Return to football training and competition after lockdown caused by the COVID-19 pandemic: medical recommendations

The lockdown caused by the COVID-19 pandemic represents a great unknown regarding the physiological changes induced in elite football players. Although it will differ from country to country, the return to sport for professional football players will follow a forced lockdown never experienced and longer than the normal annual season break. Moreover, in addition to an obvious decrease in performance, the lockdown will possibly lead to an increase of the injury risk. In fact, preseason is always a period with a specific football injury epidemiology, with an increase in the incidence and prevalence of overuse injuries. Therefore, it seems appropriate to recommend that specific training and injury prevention programmes be developed, with careful load monitoring. Training sessions should include specific aerobic, resistance, speed and flexibility training programmes. The aerobic, resistance and speed training should respect some specific phases based on the progressiveness of the training load and the consequent physiological adaptation response. These different phases, based on the current evidence found in the literature, are described in their practical details. Moreover, injury prevention exercises should be incorporated, especially focusing on overuse injuries such as tendon and muscle lesions. The aim of this paper is to provide practical recommendations for the preparation of training sessions for professional footballers returning to sport after the lockdown.

Accelerometry as a method for external workload monitoring in invasion team sports. A systematic review

Accelerometry is a recent method used to quantify workload in team sports. A rapidly increasing number of studies supports the practical implementation of accelerometry monitoring to regulate and optimize training schemes. Therefore, the purposes of this study were: (1) to reflect the current state of knowledge about accelerometry as a method of workload monitoring in invasion team sports according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines, and (2) to conclude recommendations for application and scientific investigations. The Web of Science, PubMed and Scopus databases were searched for relevant published studies according to the following keywords: "accelerometry" or "accelerometer" or "microtechnology" or "inertial devices", and "load" or "workload", and "sport". Of the 1383 studies initially identified, 118 were selected for a full review. The main results indicate that the most frequent findings were (i) devices' body location: scapulae; (b) devices brand: Catapult Sports; (iii) variables: PlayerLoadTM and its variations; (iv) sports: rugby, Australian football, soccer and basketball; (v) sex: male; (vi) competition level: professional and elite; and (vii) context: separate training or competition. A great number of variables and devices from various companies make the comparability between findings difficult; unification is required. Although the most common location is at scapulae because of its optimal signal reception for time-motion analysis, new methods for multi-location skills and locomotion assessment without losing tracking accuracy should be developed.

Accelerometry-based variables in professional soccer players: comparisons between periods of the season and playing positions

The aim of this study was to provide reference data of variation in external training loads for weekly periods within the annual season. Specifically, we aimed to compare the weekly acute load, monotony, and training strain of accelerometry-based measures across a professional soccer season (pre-season, first and second halves of the season) according to players’ positions. Nineteen professional players were monitored daily for 45 weeks using an 18-Hz global positioning system to obtain measures of high metabolic load distance (HMLD), impacts, and high intensity accelerations and decelerations. Workload indices of acute load, training monotony, and training strain were calculated weekly for each of the measures. The HMLD had greater training strain values in the pre-season than in the first (p ≤ 0.001; d = 0.793) and second halves of the season (p ≤ 0.001; d = 0.858). Comparisons between playing positions showed that midfielders had the highest weekly acute load of HMLD (6901 arbitrary units [AU]), while central defenders had the lowest (4986 AU). The pre-season period was associated with the highest acute and strain load of HMLD and number of impacts, with a progressive decrease seen during the season. In conclusion, coaches should consider paying greater attention to variations in HMLD and impacts between periods of the season and between players to individualize training accordingly.

Variations of Workload Indices Prior to Injuries: A Study in Trail Runners

The purpose of this study was to compare the variations of weekly workload indices of internal and external load measures across the three weeks prior to injury occurrences in trail runners. Twenty-five trail runners (age: 36.23 ± 8.30 years old; body mass: 67.24 ± 5.97 kg; height: 172.12 ± 5.12 cm) were monitored daily for 52 weeks using global positioning systems (GPSs) to determine the total distance covered. Additionally, a rate of perceived exertion (RPE) scale was applied to determine session-RPE (sRPE: RPE multiplied by training time). The accumulated load (AL), acute: chronic workload ratio (ACWR), training monotony (TM), and training strain (TS) indices were calculated weekly for each runner. During the period of analysis, the injury occurrences were recorded. The differences were observed in AL and ACWR for sRPE and training time were significantly greater during the injury week when compared to the previous weeks. Similar evidence was found in TM and TS indices for sRPE, training time, and total distance. Furthermore, no meaningful differences were observed in AL and ACWR for total distance in the weeks prior to injury occurrence. Nevertheless, significant between-subjects variability was found, and this should be carefully considered. For that reason, an individualized analysis of the workload dynamics is recommended, avoiding greater spikes in load by aiming to keep a progressive increment of load without consequences for injury risk.