The training-injury prevention paradox: should athletes be training smarter and harder?

Target trial framework for determining the effect of changes in training load on injury risk using observational data: a methodological commentary

In recent years, a large focus has been placed on managing training load for injury prevention. To minimise injuries, training recommendations should be based on research that examines causal relationships between load and injury risk. While observational studies can be used to estimate causal effects, conventional methods to study the relationship between load and injury are prone to bias. The target trial framework is a valuable tool that requires researchers to emulate a hypothetical randomised trial using observational data. This framework helps to explicitly define research questions and design studies in a way that estimates causal effects. This article provides an overview of the components of the target trial framework as applied to studies on load and injury and describes various considerations that should be made in study design and analyses to minimise bias.

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.

Has Sustained Time Away From Sports Due to the COVID-19 Pandemic Led to Increased Sport-Related Soft Tissue Injuries?

BACKGROUND

A decrease in sport-related injuries was observed in 2020, which has been attributed to COVID-19 and recommendations to suspend organized sports. In adult populations, increased injury rates have been noted in athletes returning to play after an extended period of reduced play, attributable to deconditioning. There is growing literature surrounding concern over increased injury risk after return to sport after the COVID-19 shutdowns.

HYPOTHESIS

Like adults, pediatric patients experience an increase in sport-related injuries after periods of "deconditioning," such as during the COVID-19 shutdown.

STUDY DESIGN

Descriptive epidemiology study.

LEVEL OF EVIDENCE

Level 4.

METHODS

The Consumer Product Safety Commission's National Electronic Injury Surveillance System database was queried to identify 13- to 18-year-old patients who sustained a sprain/strain type injury in 2019 or 2021 to an extremity, and involved sporting equipment for basketball, baseball/softball, soccer, and football. The control group was established as patients who sustained injury in 2019, and the post-COVID-19 group was established as those in 2021. Quantity of injuries sustained in these 2 groups were compared and analyzed by subgroup.

RESULTS

There was a significant difference in the total number of sport-related sprains/strains in 2019 versus 2021 (P = 0.01), with more injuries in 2019 (n = 151,067) than in 2021 (n = 104,041). There were more injuries in boys than in girls. Proportion of injuries by sports were similar in both time periods. There was a significant decrease in basketball-related injuries by 21% (P ≤ 0.01, relative risk ratio [rrr] = 0.7979) and a significant increase in football-related injuries by 14% (P = 0.01, rrr = 1.1404) and in soccer injuries by 14.2% (P = 0.03, rrr = 1.1422).

CONCLUSION

There is significant heterogeneity in injury rates by sports, with no conclusive increase in injuries, contrary to expectations.

CLINICAL RELEVANCE

This study suggests that the relationship between deconditioning and injury may be less clear in the child-athlete, and gives recommendations for return to sport after extended breaks.

STRENGTH-OF-RECOMMENDATION TAXONOMY (SORT)

Level 2c.

The Influence of Emergency Call Volume on Occupational Workload and Sleep Quality in Urban Firefighters

OBJECTIVE

The aim of the study is to determine the impact of emergency call volume on exertion, autonomic activity, and sleep among urban structural firefighters.

METHODS

Thirty-four firefighters wore a wrist-based monitor to track sleep and autonomic parameters and rated their level of perceived exertion (Borg Rating of Perceived Exertion) and subjective sleepiness after a 24-hour shift. Predictive variables included total run time and total run time after 11:59 PM.

RESULTS

Total run time and sleep duration accounted for Borg Rating of Perceived Exertion and subjective sleepiness, while total run time and total run time after 11:59 PM accounted for sleep durations on-duty.

CONCLUSIONS

The current results suggest that emergency call volume is associated with indicators of exertion and sleep. As such, call volume tracking is an important consideration for departments to ensure personnel readiness and wellness and provide a method of tracking the occupational demands experienced by firefighters on-duty.

A New Training Load Quantification Method at Supramaximal Intensity and Its Application in Injuries Among Members of an International Volleyball Team

ABSTRACT

Bouzigues, T, Maurelli, O, Imbach, F, Prioux, J, and Candau, R. A new training load quantification method at supramaximal intensity and its application in injuries among members of an international volleyball team. J Strength Cond Res XX(X): 000-000, 2024-The quantification of training loads (TLs) is essential for optimizing jump performance and reducing the occurrence of injuries. This study aimed to (a) propose a new method for quantifying TLs in explosive exercises, (b) determine the nature of the relationship between TLs dynamics and injury occurrence, and (c) assess a TL critical for training schedule purposes, above which the risk of injury occurrence becomes unacceptable. This study was conducted with 11 male volleyball players on a national team during a 5-month international competitive period. The proposed new method for quantifying TLs is based on a weighting factor applied to relative jumping intensities, determined by the number of sustainable jumps and their intensities measured by G-Vert accelerometer. The relationship between TLs dynamics and injury occurrence was assessed using a variable dose-response model. A high coefficient of determination was found between the maximum number of jumps possible and their intensities ( r2 = 0.94 ± 0.14, p < 0.001), indicating a strong physiological relationship between jumping intensities and the constraints imposed. The occurrence of injury was dependent on TLs dynamics for 2 players ( r2 = 0.26 ± 0.01; p < 0.001). The TL critical corresponded to 11 jumps over 80% of maximum jump height during games and approximately 130 jumps at <80% of maximal jump height. The present study proposes a new approach for quantifying supramaximal exercises and provides tools for training schedules and the prevention of volleyball injuries.

Practitioners' perspective of non-contact injury risk factors and injury prevention programming in professional North American male soccer

OBJECTIVE

To evaluate non-contact injury prevention strategies of professional men's soccer clubs in elite North American league soccer. To understand the application, perceived effectiveness and barriers to implementation.

DESIGN

Online cross-Sectional Study.

SETTING

North American elite soccer teams.

PARTICIPANTS

96 medical and performance support staff of elite North American teams.

MAIN OUTCOME MEASURE

The survey consisted of 20 questions and captured 1) practitioners' demographics; 2) perceptions of risk factors; 3) the use of assessment and monitoring strategies; and 4) perceptions of the implementation of injury prevention programmes'.

RESULTS

Injury prevention programmes were perceived as 'effective' (Median 4, Interquartile range 4-4) and reduced injury rates (n = 94, 98%, 95 CI% 93 to 99). A range of potential risk factors were rated as "very important" (4.58 ± 0.52 Likert scale points; mean ± standard deviation). A multi-disciplinary approach to the design, application and monitoring of programmes was generally adopted. Competing training priorities (n = 75, 78%, 95 CI% 69 to 85) and game schedules (n = 71, 74%, 95 CI% 64 to 82) were the most prevalent barriers to injury prevention implementation.

CONCLUSIONS

Injury prevention programmes were perceived as effective in reducing non-contact injuries. Managing the conflicting priorities between scheduling training, tactical and conditioning goals were considered the key barriers to desired implementation.

Relationship Between Training Load, Neuromuscular Fatigue, and Daily Well-Being in Elite Young Wrestlers

Purpose: This study investigated acute workload (wAW), chronic workload (wCW), acute: chronic workload ratio (wACWR), training monotony (wTM), perceived load training strain indicators (wTS), and countermove- ment jump (CMJ) as indicators of wellness in one season and defined weekly variations. In addition, we analyzed the relationships between training load measurements and weekly reports. Methods: 16 elite young wrestlers were monitored daily with individual observations for 46 consecutive weeks throughout the season. Training load was obtained using the session rating of perceived effort. wSleep, wStress, wFatigue & wMuscle Soreness well-being were monitored daily using the Hooper index. Results: As a result of the analysis, it was found that there is a moderate relationship (r = 0.51, p = .003) between ACWR and w mean load (A.U.) and a high relationship (r = 0.81, p < .001) between monotony and strain. Conclusion: All variables other than ACWR, w mean load, strain, and monotony presented small and statistically insignificant relationships. These results provide coaches and practitioners with new insights into perceived loads and health changes during a season at the elite youth level.

Loading or Unloading? This Is the Question! A Multi-Season Study in Professional Football Players

This study examined the impact of training load periodization on neuromuscular readiness in elite football players using the Locomotor Efficiency Index (LEI) as a measure of performance optimization. Throughout the 2021/22 and 2022/23 seasons, 106 elite male players (age: 19.5 ± 3.9 years) from an Italian professional football club were monitored using Global Positioning Systems (GPS) external load data. The LEI was derived from a machine learning model, specifically random forest regression, which compared predicted and actual PlayerLoad™ values to evaluate neuromuscular efficiency. Players were categorized by weekly LEI into three readiness states: bad, normal, and good. Analysis focused on the variation in weekly LEI relative to weekly load percentage variation (large decrease, moderate decrease, no variation, moderate increase, large increase), which included total distance, high-speed distance (above 25.2 km/h), and mechanical load, defined as the sum of accelerations and decelerations. Statistical analysis showed significant differences only with variations in total distance and mechanical load. Specifically, reducing weekly loads improved LEI in players in lower readiness states, while maintaining or slightly increasing loads promoted optimal readiness. This approach enables coaches to tailor training prescriptions more effectively, optimizing workload and recovery to sustain player performance throughout a demanding season.

Influence of the External Workload on Calf Muscle Strain Injuries in Professional Football Players: A Pilot Study

BACKGROUND

The influence of external workload variables on the development of calf muscle strainsin football players has not been previously explored.

HYPOTHESIS

Overloaded players would have an increased risk of calf muscle strain injury.

STUDY DESIGN

Prospective observational study.

LEVEL OF EVIDENCE

Level 4.

METHODS

A total of 41 professional football players from 1 team were monitored for 2 consecutive seasons. Total distance covered (TD), and distances covered at high-intensity running, high sprint running, low (LACC) and high (HACC) acceleration, low (LDEC) and high (HDEC) deceleration, and at high metabolic load distance (HMLD) were monitored with GPS units. Accumulated players' external workload in the week before injury was compared with the weekly mean value of the 6 weeks before injury occurred for each player.

RESULTS

Ten players (24.3%) suffered 16 calf muscle strain injuries (3.1 injuries per 1000 hours of match play; 0.5 injuries per 1000 hours of training exposure). Players with a calf muscle injury were older (p = 0.03), with higher body weight (p = 0.01) and height (p = 0.03). Injured players displayed substantially higher total training volume (p < 0.01), TD (p < 0.01), LACC (p < 0.01), LDEC (p < 0.01), HACC (p < 0.01), HDEC (p < 0.01), and HMLD (p = 0.03) in the week before injury, in comparison with the mean values of these variables in the 6 weeks before injury.

CONCLUSION

A week with a higher-than-habitual external workload might increase the risk of calf muscle strain injury in professional football players. Calf muscle injuries were preceded by a week with unusually high workloads associated with accelerating and decelerating distances and higher training volumes.

CLINICAL RELEVANCE

Monitoring external workload indicators may be helpful in determine players with a higher risk of calf muscle strain injury due to excessive workload during training/competition.

Asymmetric running is associated with pain during outdoor running in individuals with Achilles tendinopathy in the return-to-sport phase

OBJECTIVES

To determine the relationships between (1) Achilles tendon pain and loading symmetry, and (2) number of running bouts and symptom severity, during two weeks of outdoor running in individuals with Achilles tendinopathy.

DESIGN

Prospective, observational study.

SETTING

Biomechanics laboratory and outdoors.

PARTICIPANTS

Seventeen runners with Achilles tendinopathy in the return-to-sport phase of rehabilitation.

MAIN OUTCOME MEASURES

Symptom severity was recorded with the Victorian Institute of Sports Assessment-Achilles (VISA-A) questionnaire. Running bouts and Achilles tendon pain during runs were recorded with daily training logs. Ground contact time was collected during runs with wearable sensors. Linear mixed modeling determined if the relationship between Achilles tendon pain and ground contact time symmetry during running was moderated by consecutive run days. Multiple regression determined the relationship between number of running bouts and change in VISA-A scores over two weeks, adjusted for run distance.

RESULTS

Greater ground contact time on the contralateral leg corresponded to increased ipsilateral tendon pain for each consecutive run day (b = -0.028, p < 0.001). Number of running bouts was not associated with 2-week changes in VISA-A scores (p = 0.672).

CONCLUSIONS

Pain during running is associated with injured leg off-loading patterns, and this relationship strengthened with greater number of consecutive run days. Number of running bouts was not related to short-term symptom severity.

Epidemiology of injuries in elite female rink hockey players: A two season observational study

OBJECTIVES

To record the time-loss injuries of female rink hockey players and describe the affected region, tissue, and onset of injury.

DESIGN

Cross-sectional survey study.

SETTING

First (Ok Liga) and Second (Plata) division clubs.

PARTICIPANTS

280 player-seasons.

MAIN OUTCOME MEASURES

Incidence of overall, training, and match injuries (number of injuries per 1000 h) from two seasons.

RESULTS

A total of 229 injuries occurred in 56,438 h of exposure. The overall incidence was 4 injuries per 1000 h (4/1000 h), with a significantly higher rate of injuries during matches (15.2/1000 h) compared to training sessions (2.6/1000 h) (p < 0.001). Injuries affecting the lower limb were the most common (2.3/1000 h), followed by upper limb (1.2/1000 h), and head/trunk (0.6/1000 h). The tissue with the highest incidence of injury was the muscle/tendon (1.3/1000 h), followed by the ligament (0.8/1000 h). Around one in every three injuries (31%) affected either the thigh or hip/groin (73 injuries).

CONCLUSIONS

The injury incidence in elite female rink hockey is moderate and occurs mainly during match sessions. Preventative measurements should be implemented in rink hockey with a special concern for injuries affecting the thigh, and hip/groin.

Which training load indicators are greater correlated with maturation and wellness variables in elite U14 soccer players?

BACKGROUND

Monitoring of training load is done to improve physical performance and minimize the incidence of injuries. The study examined the correlation between accumulated training load parameters based on periods with maturity (i.e., maturity offset and peak height velocity -PHV- and wellness variables -e.g., stress and sleep quality-). The second aim was to analyze the multi-linear regression between the above indicators.

METHODS

Twenty elite young U14 soccer players (M = 13.26 ± 0.52 years, 95% CI [13.02, 13.51]) were evaluated over 26 weeks (early, mid, and end-season) to obtain stress, sleep quality, and measures of workload in the season (accumulated acute workload [AW], accumulated chronic workload [CW], accumulated acute: chronic workload ratio [ACWLR], accumulated training monotony [TM], accumulated training strain [TS]).

RESULTS

The analysis revealed a moderate, statistically significant negative correlation between sleep quality and training monotony (r = -0.461, p < 0.05). No significant correlations were observed between other variables (p > 0.05). In the multi-linear regression analysis, maturity, PHV, sleep, and stress collectively accounted for variances of 17% in AW, 17.1% in CW, 11% in ACWLR, 21.3% in TM, and 22.6% in TS. However, individual regression coefficients for these predictors were not statistically significant (p > 0.05), indicating limited predictive power.

CONCLUSION

The study highlights the impact of sleep quality on training monotony, underscoring the importance of managing training load to mitigate the risks of overtraining. The non-significant regression coefficients suggest the complexity of predicting training outcomes based on the assessed variables. These insights emphasize the need for a holistic approach in training load management and athlete wellness monitoring.

A Longitudinal Mixed Methods Case Study Investigation of the Academic, Athletic, Psychosocial and Psychological Impacts of Being a Sport School Student Athlete

BACKGROUND

Sport schools are popular environments for simultaneously delivering education and sport to young people. Previous research suggests sport school involvement to have impact (i.e. the positive/negative, intended/unintended and long/short-term outcomes, results and effects) on student athlete's holistic (i.e. academic, athletic, psychosocial and psychological) development. However, previous research is limited by (1) cross-sectional methods, (2) limited multidimensional assessments, (3) lack of consideration for athlete characteristics (e.g. sex) and (4) failure to evaluate how sport school features affect student-athlete impacts.

OBJECTIVES

The study, using a mixed methods case study approach, aims to (1) longitudinally evaluate the impact of sport school involvement on the holistic development of student athletes, (2) evaluate the impact on holistic development by student-athlete characteristics and (3) explore the features and processes of the sport-school programme that drive/facilitate holistic impacts.

METHODS

A longitudinal mixed methods design was employed across one full academic school year (33 weeks). Six data-collection methods (i.e. online questionnaire, physical fitness testing battery, academic assessment grades, log diaries, field notes/observation and timeline diagram/illustration) were used to assess the academic, athletic, psychosocial and psychological impacts for 72 student athletes from one sport school in the United Kingdom (UK).

RESULTS

Student athletes developed positive long-term holistic overall impacts (i.e. academically, athletically and personally), including maintaining stable and relatively high levels of sport confidence, academic motivation, general recovery, life skills, resilience and friends, family and free time scores. Despite positive impacts, juggling academic and sport workload posed challenges for student athletes, having the potential to lead to negative holistic impacts (e.g. fatigue, stress and injury). Positive and negative impacts were linked to many potential features and processes of the sport school (e.g. academic and athletic support services versus insufficient training load build-up, communication, coordination, flexibility and planning). Furthermore, when considering student-athlete characteristics, females had lower sport confidence, higher general stress and body image concerns and less general recovery than males and student athletes who played sport outside the school had lower general recovery.

CONCLUSIONS

This mixed method, longitudinal study demonstrated sport school involvement resulted in many positive academic (e.g. good grades), athletic (e.g. fitness development), psychosocial (e.g. enhanced confidence) and psychological (e.g. improved resilience) impacts attributed to the academic and athletic support services provided. However, juggling heavy academic and athletic workloads posed challenges leading to negative impacts including fatigue, pressure, stress and injury. Furthermore, holistic impacts may be sex dependent and further support may be required for female student athletes in sport school environments. Overall, these findings demonstrate the complex nature of combining education and sport commitments and how sport schools should manage, monitor and evaluate the features of their programme to maximise the holistic impacts of sport-school student athletes.

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.

Study protocol for a prospective cohort study describing the injury characteristics in elite gymnasts in TeamGym: the Swedish TeamGym Injury Cohort - STIC

INTRODUCTION

Gymnastics consists of several different disciplines, whereof TeamGym is one. TeamGym is a young discipline with sparse research. The aim of the study is to investigate the injury characteristics in Swedish elite gymnasts competing in TeamGym including training load and other physical and psychological factors associated with injury.

METHODS AND ANALYSIS

The Swedish TeamGym Injury Cohort is a longitudinal prospective cohort study for 52 weeks that includes the junior (15-17 years) and senior (≥18 years) Swedish female and male national teams in TeamGym. A baseline questionnaire will be sent out in an online application (SmartaBase) regarding demographics, previous injuries, gymnastics-related factors, for example, time at elite level and psychosocial factors such as stress, athletic identity, coping skills, personality traits and coach-athlete relation. A weekly questionnaire will be sent out in SmartaBase every Sunday and will monitor injuries using the Oslo Sports Trauma Research Centre Overuse Questionnaire, gymnastics-related factors, for example, landing surfaces, stress, recovery and training load. A test battery for the lower extremity will be performed. Data for ankle dorsiflexion, hop tests and ankle plantarflexion strength/endurance will be collected.

ETHICS AND DISSEMINATION

This project was approved by the Swedish Ethical Review Authority (2023-06653-01) and is performed according to the Declaration of Helsinki. The results will be published in peer-reviewed journals, scientific conferences and shared with the Swedish Gymnastics Federation.

Injury prevention for women and girls playing Australian Football: programme cocreation, dissemination and early adopter coach feedback

Background

Adherence to injury prevention programmes may improve with greater end-user involvement and application of implementation frameworks during development. We describe the cocreation, initial dissemination and feedback from programme early adopters (coaches), to develop the first evidence-informed injury prevention programme for women playing community Australian Football (Prep-to-Play).

Methods

We used a pragmatic seven-step process for developing sports injury prevention programmes to (1) gain organisational support, (2) compile research evidence, (3) consult experts, (4) engage end-users, (5) test programme acceptability, (6) evaluate against theory and (7) gain early adopter feedback. All Australian Football-registered coaches of women's/girls' teams were sent a postseason survey to determine initial awareness, adoption and implementation (steps 5 and 6). Purposively selected coaches were invited to interviews/focus groups (step 7) to identify competency, organisational and leadership implementation drivers with a deductive thematic analysis applied.

Results

Prep-to-Play was cocreated using previous efficacious programmes and expert input (steps 1-4), and disseminated via the national sporting organisation in preseason 2019 to all registered coaches (step 5). 343 coaches (90 women) completed the postseason survey and 22 coaches (5 women) participated in an interview (n=9) or focus group (n=13) (steps 6 and 7). 268 coaches (78%) were aware of Prep-to-Play. Of those aware, 218 (81%) had used (at least one element) Prep-to-Play, and 143 (53%) used it at least twice per week. Competency drivers included local expert-delivered face-to-face workshops complimented by online content and ongoing support. Organisational drivers included coach education integrated into existing league/club. Leadership drivers included compulsory injury prevention education integrated into coach reaccreditation processes or incentivisation via recognition (eg, professional development points).

Conclusions

Cocreation and organisational support resulted in high programme awareness and adoption. However, high fidelity implementation and maintenance may need to be facilitated by competency, organisational and leadership drivers. Responsibility should be shared among all stakeholders.

On-field rehabilitation in football: current practice and perceptions. A survey of the English Premier League and Football League

INTRODUCTION

Return to play related research is increasing rapidly, with two recent competency-based frameworks offering conceptualised support for on-field rehabilitation (OFR) decision-making. It is still unknown, however, who is responsible for OFR and how they typically select, monitor, and progress OFR processes.

AIMS

The purpose of this study was to investigate current OFR practice within English professional football to support practitioners with decision-making and highlight opportunities for future research related to the design, monitoring, and progression of OFR.

METHODS

Sixty-nine practitioners responsible for the design and implementation of OFR at 69 clubs (75% of the English Premier League and Football League) responded to a survey containing 30 questions (14 open and 16 closed).

RESULTS

The main findings were that therapists (physiotherapists/sports therapists) have the largest influence on OFR, followed by physical performance coaches (sports scientists/strength and conditioning coaches), technical coaches and medical doctors. There was more agreement for the ordering of specific OFR drills earlier in the process when activities are easier to control. The most frequently reported objective monitoring tool was global positioning systems (GPS), with functional/clinical experience/expertise remaining subjectively vital. GPS outputs (e.g., sprint metrics and accelerations/decelerations) were most used for between session decision-making, with verbal communication being key for within session decision-making.

CONCLUSION

Future research should use evidence of current practice, such as drill design and monitoring techniques, to explore drill-level analysis and give practitioners greater insights into which stage of current OFR frameworks specific drills fall, and how they might be more objectively progressed/regressed.

Descriptive analysis of injury types and incidence during futsal preseason across different competitive levels

Introduction

This study aimed to verify the typology and incidence of injury by comparing the different competitive levels of futsal during the preseason.

Methods

The sample consisted of 68 senior male futsal players (24.26 ± 4.63 years). Data were collected using an injury recording grid that examined the affected body part, anatomical region, type of injury, mechanism, and severity.

Results

It was found that the elite group has the lowest incidence rate of injury (4.8 injuries per 1,000 h of exposure) compared to the sub-elite (11.8 injuries per 1,000 h of exposure) and amateur groups (13.9 injuries per 1,000 h of exposure). However, at this level, there is the highest percentage of injury occurrence (38.5%), the lower limb was the most affected part of the body (30.8%), and ligament (23.1%) and muscle (15.4%) injuries are the most prevalent. The most frequent mechanism of injury was non-traumatic (30.8%), and the majority were moderate injuries in the elite (23.1%) and sub-elite (17.9%) groups and severe injuries in the amateur group (12.5%).

Discussion

The amateur futsal players had the highest incidence of injury during the preseason period compared to the other competitive levels. Still, it was at the elite level where the highest percentage of injuries occurred, most of them non-traumatic and of ligament origin, primarily affecting the ankle region. The results highlight the importance of adopting specific injury prevention programs for ligament and muscle injuries during the preseason phase, regardless of the competitive level.

Physical and psychological impact of surgery on the operating surgeon

The impact of surgery on the surgeon's well-being encompasses both physical and psychological aspects. Physically, surgeons are at risk of work-related musculoskeletal symptoms due to the nature of their work, and this risk can be impacted by theater environment, equipment design, and workload. Many symptoms will be self-limiting, but work related musculoskeletal symptoms can lead to the development of an injury, which can have far reaching effects, including the need for medical or surgical treatment, time away from work, or a change in clinical duties. Additionally, surgery can place a significant cognitive workload on the lead operator and this can be exacerbated, or alleviated, by the surgical environment, experience of the assistance, surgical modality, and case complexity. Measuring and quantifying the impact of surgery on the surgeon is a challenging undertaking. Tools such as motion capture, physiological markers, including heart rate variability and salivary cortisol, and questionnaires can provide insights into understanding the overall impact of surgery on the surgeon. A holistic approach that incorporates injury prevention strategies, communication, and support, is vital in assessing and mitigating risk factors. Injury prevention assessment tools and interventions that can be used within the busy surgical environment are needed, alongside increased ergonomic awareness. Addressing the impact of surgery on the surgeon is a multifaceted challenge, and long term positive changes can only be sustained with the support of the whole surgical team and healthcare organizations by developing and maintaining a supportive working environment.

Olecranon stress fracture in a gymnastics player: Insight into an early detection and integrated care approach: Case report

We describe a case report of a 13 year-old a gymnastic athlete who was diagnosed with an olecranon stress fracture associated with mild medial epicondyle apophysitis, Following a brief review of the literature on this case, the researchers call attention to the significance of and imaging assessment especially MR in determining the correct diagnosis and identifying concomitant injuries. MRI findings concluded firstly a marked bone marrow edema seen at the posterior medial aspect of the olecranon with linear low signal traversing the olecranon related to a stress fracture. Secondly, subchondral linear low signal and bone marrow edema at the radial head related to another stress fracture/reaction injury. Thirdly, bone marrow edema at the medial apophysis with overlying soft tissue edema suggestive for medial epicondylitis.

Mindfulness Practice Is Associated With Improved Well-Being and Reduced Injury Risk in Female NCAA Division I Athletes

BACKGROUND

Injury in sport is an inherent risk to participation, and it can have devastating consequences for the athlete, both mentally and physically. Previous research has found that impairments in well-being can increase the risk of injury, and that various forms of mindfulness training and practice can improve well-being and mental health in various populations.

HYPOTHESIS

Mindfulness would be associated with greater well-being and lower risk of injury.

STUDY DESIGN

Cohort study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A total of 21 female Division I athletes underwent a formal 6-week mindfulness training program and were encouraged to continue mindfulness exercises. The athletes completed daily surveys on their smartphones in relation to mood, muscle readiness (soreness), readiness to train, energy level, daily training load, and whether they had participated in mindfulness training that day. Linear mixed effects models were used to evaluate well-being variables and mindfulness state, and separate mixed effects logistics regression models were used to evaluate injury incidence and wellness variables.

RESULTS

On days with mindfulness practice, athletes reported higher mood (19.6 [18.8-20.3] vs 19.4 [18.6-20.1, P = 0.03), muscle readiness (18.9 [17.8-20.0] vs 18.6 [17.5-19.6], P = 0.03), readiness to train (78.7 [75.9-81.5] vs 77.4 [74.7-80.2], P < 0.01), and energy level (19.3 [18.6-20.1] vs 18.8 [18.1-19.5, P < 0.01) than on the days when they did not participate in mindfulness training. Mindfulness practice was associated with significantly reduced likelihood of suffering an acute injury the following day (odds ratio, 0.42; 95% CI, 0.42-0.43; P < 0.01).

CONCLUSION

On an individual level, participation in mindfulness by female collegiate athletes was associated with a dramatic reduction in injury risk the following day. In addition, mindfulness was associated with significantly improved mood, muscle readiness, readiness to train, and energy level.

CLINICAL RELEVANCE

These findings suggest that mindfulness training in athletes may improve well-being and reduce the risk of injury among high-level athletes.

Repeated-Sprint Training With Blood-Flow Restriction Improves Repeated-Sprint Ability Similarly to Unrestricted Training at Reduced External Loads

PURPOSE

This study examined performance and physiological adaptations following 3 weeks of repeated-sprint training (RST) with blood-flow restriction (BFR) or without (non-BFR).

METHODS

Twenty-six semiprofessional and amateur adult male team-sport players were assessed for repeated-sprint ability, anaerobic capacity, leg lean mass, neuromuscular function, and maximal aerobic capacity before and after RST. Participants completed 9 cycling RST sessions (3 sets of 5-7 × 5-s sprints, 25-s passive recovery, 3-min rest) over a 3-week period with BFR or non-BFR.

RESULTS

During RST sessions, the BFR group demonstrated lower mean power output compared with non-BFR (-14.5%; g = 1.48; P = .001). Significant improvements (P < .05) in mean and peak power output during repeated-sprint ability (+4.1%; g = 0.42, and + 2.2%; g = 0.25, respectively) and anaerobic capacity (+4.8%; g = 0.47, and + 4.7%; g = 0.32, respectively) tests, leg lean mass (+2.0%; g = 0.16), and peak aerobic power (+3.3%; g = 0.25) were observed from pretesting to posttesting without any between-groups differences. No significant changes (P > .05) were observed for maximal isometric voluntary contraction and maximal aerobic capacity. Peak rate of force development decreased (P = .003) in both groups following RST (-14.6%; g = 0.65), without any between-groups differences.

CONCLUSIONS

Repeated-sprint ability, anaerobic capacity, leg lean mass, and peak aerobic power improved following 3 weeks of RST; however, the addition of BFR did not further enhance adaptations. Interestingly, comparable improvements were achieved between groups despite lower external loads experienced during RST sessions with BFR.

COVID-19 National Football League (NFL) Injury Analysis: Follow-Up Study

Background

In 2020, COVID-19 spread across the world and brought normal daily life to a halt, causing the shutdown of nearly everything in order to prevent its spread. The National Football League (NFL) similarly experienced shutdowns and the resulting effects, leaving athletes unable to train in some of the most advanced facilities with many of the best trainers in the world. A previous study, titled COVID-19 Return to Sport: NFL Injury Prevalence Analysis, determined that there was increased injury prevalence during the 2020 season, likely due to decreased physiological adaptations within athletes' bodies as a result of facility shutdowns. Understanding injury epidemiology is vital to the prevention of injuries and the development of return-to-play protocols.

Objective

The objective of this study is to perform a follow-up study to COVID-19 Return to Sport: NFL Injury Prevalence Analysis in order to examine the longitudinal effects of the COVID-19 pandemic on injury epidemiology. This study examines if there was a recovery to baseline levels of injuries or if there are still lingering effects from the COVID-19 pandemic-induced spike in injuries.

Methods

To determine if there was change in the number of injuries for each season, injury tallies collected from the 17-week-long 2018, 2019, and 2020 NFL regular seasons were compared with those from the 18-week-long 2021 and 2022 NFL regular seasons. A Kruskall-Wallis test with post hoc Dunn analysis was conducted to compare the rate of injuries per team per week between each of the 2018, 2019, 2020, 2021, and 2022 regular seasons.

Results

The Kruskall-Wallis test revealed an H statistic of 32.61 (P<.001) for the comparison of the injury rates across the 5 seasons. The post hoc Dunn analysis showed that 2020 had a statistically significant difference when compared with each of the 2018 (P<.001), 2019 (P=.04), 2021 (P=.02), and 2022 (P=.048) seasons. The 2019 season showed no statistical significance when compared with the 2021 (P=.23) and 2022 (P=.13) seasons.

Conclusions

The results of this follow-up study, combined with the previous study, show that extended training interruptions stemming from COVID-19 in 2020 induced detraining and led to increased injuries. Additionally, the results of this study show that retraining can occur, resulting in the development of injury protective factors, as injury rates returned to baseline levels after 2020. This is the first large-scale and long-term opportunity to demonstrate the effects of these principles and how they are important to understanding injury epidemiology.

Physical Exercise After Solid Organ Transplantation: A Cautionary Tale

An increasing body of randomized controlled trials suggests the safety of engaging in moderate to vigorous intensity exercise training following solid organ transplantation. Fueled by emerging sport events designed for transplant recipients and the ever-growing body of research highlighting the diverse health benefits of physical activity, transplant recipients are now increasingly participating in strenuous and occasionally competitive physical endeavors that largely surpass those evaluated in controlled research settings. This viewpoint article adopts a cautionary stance to counterbalance the prevalent one-sided optimistic perspective regarding posttransplant physical activity. While discussing methodological limitations, we explore plausible adverse impacts on the cardiovascular, immunological, and musculoskeletal systems. We also examine the physiological consequences of exercising in the heat, at high altitude, and in areas with high air pollution. Risks associated with employing performance-enhancing strategies and the conceivable psychological implications regarding physical activity as a tribute to the 'gift of life' are discussed. With a deliberate focus on the potential adverse outcomes of strenuous posttransplant physical activity, this viewpoint aims to restore a balanced dialogue on our comprehension of both beneficial and potentially detrimental outcomes of physical activity that ultimately underscores the imperative of well-informed decision-making and tailored exercise regimens in the realm of posttransplant care.

Hamstring stiffness and injury risk factors during the handball season in female players

Monitoring the muscle mechanical properties and functions of female athletes throughout their training season is relevant to understand the relationships between these factors and to predict noncontact injuries, which are prevalent among female athletes. The first aim of this study was to determine whether female handball players' passive stiffness of the hamstring muscles is associated with hamstring extensibility, strength of knee flexors and extensors, and lower limb stiffness. Additionally, the study monitored fluctuations in these factors over 25 weeks. The study utilized an isokinetic dynamometer to record hamstring passive stiffness, extensibility, and hamstring and quadriceps strength of 18 young handball players. Lower limb stiffness was determined from a countermovement vertical jump conducted on a force plate. The countermovement jump involved the calculation of the peak force during the eccentric phase and the mean force during the concentric phase. The results showed a positive correlation between hamstring passive stiffness and lower limb stiffness (r = 0.660, p < 0.01), knee flexion and extension strength (r = 0.592, p < 0.01 and r = 0.497, p < 0.05, respectively), and eccentric peak force (r = 0.587, p < 0.01) during jumping. The strength of knee extensors increased significantly after 6 weeks, and hamstring stiffness after 12 weeks of training. In conclusion, the increased hamstring stiffness following training did not match other factors associated with injury risk. Therefore, preventing multifactorial injury risk requires a comprehensive approach, and monitoring one factor alone is insufficient to predict noncontact injuries in female handball players.

Workload Comparison of Contemporary Interval Throwing Programs and a Novel Optimized Program for Baseball Pitchers

Background

In the rehabilitation of injured baseball pitchers, there is lack of consensus on how to guide a player back to pitching. It is unknown how different contemporary interval throwing programs (ITPs) progress in the amount of throwing workload.

Purposes

To 1) evaluate three prominent ITPs commonly employed in baseball pitcher rehabilitation and assess whether these ITPs produce training loads that increase in a controlled, graduated manner and 2) devise an ITP that produced training loads which increased steadily over time.

Study Design

Cross-sectional study.

Methods

Three publicly available ITPs from prominent sports medicine institutions were analyzed. Elbow varus torque per throw was calculated from a 2nd order polynomial regression based upon a relationship between recorded torque measurements and throwing distance measured from a database of 111,196 throws. The relative rate of workload increase was measured as an acute:chronic workload ratio (ACWR). For each ITP, throw counts, daily/acute/chronic workloads, and ACWR were calculated and plotted over time. Finally, an original ITP was devised based upon a computational model that gradually increases ACWR over time and finished with an optimal chronic workload.

Results

Each ITP exhibited a unique progression of throwing distances, quantities, and days to create different workload profiles. The three ITPs had throwing schedules ranging from 136 days to 187 days, ACWR spiked above or fell below a literature-defined "safe" range (i.e. 0.7 - 1.3) 19, 21, and 23 times. A novel ITP, predicated on a 146-day schedule and with a final chronic workload of 14.2, was designed to have no spikes outside of the safe range.

Conclusion

Existing ITPs widely utilized for rehabilitation of baseball pitchers exhibit significantly inconsistent variation in the rate of throwing load progression. Computational modeling may facilitate more incremental workload progression in ITPs, thereby reducing injury during rehabilitation and more efficiently condition a pitcher for return to competition.

Level of Evidence

3b.

'Benched' the effect of the COVID-19 lockdown on injury incidence in sub-elite football in Australia: a retrospective population study using injury insurance records

OBJECTIVES

The primary aim of this study was to compare injury rates pre- and post-COVID-19 lockdown in sub-elite football (soccer) players by analysing the full season and the first month of each season between 2018 and 2020. Secondary aims were to describe the incidence, location and type of injuries and to compare injuries by age group and sex.

DESIGN

Descriptive epidemiological study.

METHODS

A de-identified insurance database was retrospectively coded using the Orchard Sports Injury Classification System. Injury incidence per 1000 hours as well as incidence rate ratios (IRR) with confidence intervals were calculated.

RESULTS

No significant difference was found in the overall incidence rate in 2020 compared with the 2018 and 2019 seasons (IRR, 1.04 [95% CI, 0.96-1.13]; p = 0.294). However, overall injuries increased by 26% (IRR: 1.26 [95% CI 1.07-1.47]; p < 0.005) and joint sprains increased by 45% (IRR: 1.45 [95% CI 1.14-1.84]; p < 0.005) in the first month of 2020 compared with 2018-2019. Between 2018 and 2020, there were 4149 injury insurance claims, with anterior cruciate ligament (ACL) ruptures accounting for 19% of all injuries. When comparing sex, female players had significantly more ankle sprains whilst male players suffered more dental injuries.

CONCLUSIONS

This study adds to a growing body of evidence investigating injury rates post-COVID-19 lockdowns in sport. Sub-elite players appear to be at higher risk of joint injuries within the first month of training following a period of lockdown. Overall, stakeholders involved in sub-elite football should prioritise knee and ankle joint injury prevention.

Cross-sectional insights into exercise physiology knowledge among medical students in Jordan

Objectives

Exercise physiology is a branch of physiology that studies how physical activity and exercise alter the structure and function of living organisms. Knowledge of exercise physiology is crucial to improve athletic performance, improve people's ability to cope with extreme circumstances and approach chronic diseases. This research aimed to evaluate the knowledge of future healthcare professionals, namely, the medical students in Jordan regarding exercise physiology.

Methods

Responses were collected from 524 undergraduate medical students enrolled in clinical clerkship. An online survey that evaluated participants' basic understanding of various physiological concepts related to physical exercises, such as respiratory exchange ratio, physical fitness, V̇O2 max and exercise at high altitudes was employed in the study.

Results

63.2% of participants had a poor level of exercise physiology knowledge. Misconceptions regarding V̇O2 max definition (93.3%), application (46.4%), significance (35.6%) and related physiological factors (48.7%) were observed. Students had misconceptions about physical fitness evaluation questions (52.5%, 39%, and 41.8%, respectively). Student proportions of 37%, 41%, 80.3% and 73.1% showed misconceptions about muscle groups and energy systems during training, training prescription variables, respiratory exchange ratio, and high-altitude performance, respectively. Significant differences in knowledge levels were found based on respondent characteristics (p < 0.05).

Conclusions

Knowledge of exercise physiology is more than desirable for medical professionals. Therefore, efforts must be made to increase awareness and improve knowledge about basic physiological fundamentals related to exercise physiology among medical students in Jordan, as they represent the backbone of healthcare professionals of the future who will deal with medical conditions related to physical activity and exercise.

Finding the Goldilocks Zone of Mechanical Loading: A Comprehensive Review of Mechanical Loading in the Prevention and Treatment of Knee Osteoarthritis

In this review, we discuss the interaction of mechanical factors influencing knee osteoarthritis (KOA) and post-traumatic osteoarthritis (PTOA) pathogenesis. Emphasizing the importance of mechanotransduction within inflammatory responses, we discuss its capacity for being utilized and harnessed within the context of prevention and rehabilitation of osteoarthritis (OA). Additionally, we introduce a discussion on the Goldilocks zone, which describes the necessity of maintaining a balance of adequate, but not excessive mechanical loading to maintain proper knee joint health. Expanding beyond these, we synthesize findings from current literature that explore the biomechanical loading of various rehabilitation exercises, in hopes of aiding future recommendations for physicians managing KOA and PTOA and athletic training staff strategically planning athlete loads to mitigate the risk of joint injury. The integration of these concepts provides a multifactorial analysis of the contributing factors of KOA and PTOA, in order to spur further research and illuminate the potential of utilizing the body's own physiological responses to mechanical stimuli in the management of OA.

The Connection Between Resistance Training, Climbing Performance, and Injury Prevention

BACKGROUND

Climbing is an intricate sport composed of various disciplines, holds, styles, distances between holds, and levels of difficulty. In highly skilled climbers the potential for further strength-specific adaptations to increase performance may be marginal in elite climbers. With an eye on the upcoming 2024 Paris Olympics, more climbers are trying to maximize performance and improve training strategies. The relationships between muscular strength and climbing performance, as well as the role of strength in injury prevention, remain to be fully elucidated. This narrative review seeks to discuss the current literature regarding the effect of resistance training in improving maximal strength, muscle hypertrophy, muscular power, and local muscular endurance on climbing performance, and as a strategy to prevent injuries.

MAIN BODY

Since sport climbing requires exerting forces against gravity to maintain grip and move the body along the route, it is generally accepted that a climber`s absolute and relative muscular strength are important for climbing performance. Performance characteristics of forearm flexor muscles (hang-time on ledge, force output, rate of force development, and oxidative capacity) discriminate between climbing performance level, climbing styles, and between climbers and non-climbers. Strength of the hand and wrist flexors, shoulders and upper limbs has gained much attention in the scientific literature, and it has been suggested that both general and specific strength training should be part of a climber`s training program. Furthermore, the ability to generate sub-maximal force in different work-rest ratios has proved useful, in examining finger flexor endurance capacity while trying to mimic real-world climbing demands. Importantly, fingers and shoulders are the most frequent injury locations in climbing. Due to the high mechanical stress and load on the finger flexors, fingerboard and campus board training should be limited in lower-graded climbers. Coaches should address, acknowledge, and screen for amenorrhea and disordered eating in climbers.

CONCLUSION

Structured low-volume high-resistance training, twice per week hanging from small ledges or a fingerboard, is a feasible approach for climbers. The current injury prevention training aims to increase the level of performance through building tolerance to performance-relevant load exposure and promoting this approach in the climbing field.

Ligament Injuries in Professional Male Handball Players: A 6-Year Longitudinal Study

Handball is a sport that involves high-intensity actions throughout the game, such as sprints, jumps, landings, and high-speed, repeated throws. This, along with competitive and tactical factors, congested schedules, and the need to maintain a high level of performance throughout the season, contributes to a high injury rate. This study aimed to analyse ligament injuries in a professional handball team over six consecutive seasons. A total of 68 elite male Spanish handball players participated, with 54 time-loss injuries (i.e., injuries involving at least one day of absence) observed during this study period. Ligament injury information was recorded following the International Olympic Committee consensus statement. The overall incidence was 0.89 ligament injuries per 1000 h of exposure. Additionally, a higher incidence and burden of ligament injuries was observed during match-play compared to training. Most ligament injuries were classified as minor or moderate (i.e., 79.63% of the total), and 46.29% were reinjuries. A significantly higher incidence of ligament injuries was suffered in the lower limbs compared to the upper limbs (0.81 vs. 0.08 ligament injuries per 1000 h; p < 0.001). Specifically, the highest incidence was observed in the anterior talofibular ligament of the ankle (0.57 injuries per 1000 h of exposure), while the greatest burden was related to the anterior cruciate ligament (24.08 absence days per 1000 h of exposure). This study provides an overview of ligament injuries among professional handball players, highlighting the need to implement strategies with positive effects during competition (e.g., specific activation strategies or training programmes based on strength and balance) and to reduce injury recurrences.

Unraveling the "golden ratio": a pilot study investigating acute-to-chronic workload ratio in breast cancer patients undergoing active treatment

Training load monitoring is a common practice in sports medicine for supporting athletes' health and performance. Despite progress in exercise oncology research for breast cancer patients, training load monitoring is underutilized. This study retrospectively investigated the relationship between maintained training load within a defined range and physical and health outcomes of ten breast cancer patients during active anticancer treatment who underwent a 12-week exercise program. Intervention consisted of endurance and resistance training, three times a week, with each session lasting 30-45 min. Assessments were conducted at baseline, 6 and 12 weeks after enrollment, evaluating physical function (6-min walk test-6MWT, and sit-to-stand), muscle strength, body composition, sleep quality (Pittsburgh Sleep Quality Index-Pittsburgh Sleep Quality Index), quality of life (EORTC-QLQ-C30), heart rate variability and physical activity levels (International Physical Activity Questionnaire-International Physical Activity Questionnaire). The Physiological Cost Index/Energy Expenditure Index (PCI/EEI) was estimated using the 6MWT and Heart rate. Training load monitoring was performed by session rating of perceived exertion (sRPE, relative intensity multiplying with session duration). Acute-to-Chronic Workload Ratio (ACWR) (7:28, rolling average) was calculated accordingly. Analyses were performed within-subjects across time points and between-subjects, comparing those who maintained from weeks 6-12 an ACWR of 0.8-1.3 with those who did not. Adherence rates were similar between groups. Physical function improved in the total sample with large effect sizes (Δ6MWT = 56.5 m [95%CI: 6-100 m], effect size [w] = 0.52, p = 0.006; ΔSit-to-Stand = 1.5 [95%CI: 1-5], effect size [w] = 0.681, p < 0.001), demonstrating greater changes in patients with higher ACWR. Sleep quality improvements were higher in the appropriate ACWR group (p = 0.016). A positive correlation was demonstrated between global health status and 6MWT change from baseline to 12 weeks (ρ = 0.689, p = 0.04). Despite a small sample size, patients maintaining sufficient relative training load presented greater physical fitness and sleep quality improvements. Thus, training load monitoring may enhance exercise program benefits in breast cancer patients under active treatment.

A moderated mediation analysis on the influence of social support and cognitive flexibility in predicting mental wellbeing in elite sport

The purpose of this study was to examine the mechanism by which social support influences mental wellbeing. Using the thriving through relationships model to provide a theoretical underpinning, cognitive flexibility was hypothesised as a mediator. Additionally, the research examined the consistency of this pathway between elite athletes, retired athletes, and non-athletes. Survey responses from a sample of 247 participants (n = 49 elite athletes, n = 61 retired athletes, n = 137 convenience sample; of which 127 (51.4%) were males were included in the analysis. Initial mediation analysis revealed a significant indirect pathway from social support to mental wellbeing through cognitive flexibility. Moderated mediation analysis revealed this pathway was significant for retired athletes and the convenience sample, but not for elite athletes. Results provide additional insight into the mechanisms by which social support influences wellbeing. Cognitive flexibility interventions may not be as effective for elite athletes.

Using wearable technology data to explain recreational running injury: A prospective longitudinal feasibility study

OBJECTIVES

Investigate 1) if collecting and analysing wristwatch inertial measurement unit (IMU) and global positioning system (GPS) data using a commercially-available training platform was feasible in recreational runners and 2) which variables were associated with subsequent injury.

DESIGN

Prospective longitudinal cohort.

PARTICIPANTS

Healthy recreational runners.

MAIN OUTCOME MEASURES

We set a priori feasibility thresholds for recruitment (maximum six-months), acceptance (minimum 80%), adherence (minimum 70%), and data collection (minimum 80%). Participants completed three patient-reported outcome measures (PROMS) detailing their psychological health, sleep quality, and intrinsic motivation to run. We extracted baseline anthropometric, biomechanical, metabolic, and training load data from their IMU/GPS wristwatch for analysis. Participants completed a weekly injury status surveillance questionnaire over the next 12-weeks. Feasibility outcomes were analysed descriptively and injured versus non-injured group differences with 95% confidence intervals were calculated for PROM/IMU/GPS data.

RESULTS

149 participants consented; 86 participants completed (55 men, 31 women); 21 developed an injury (0.46 injuries/1000km). Feasibility outcomes were satisfied (recruitment = 47 days; acceptance = 133/149 [89%]; adherence = 93/133 [70%]; data collection = 86/93 [92%]). Acute load by calculated effort was associated with subsequent injury (mean difference -562.14, 95% CI -1019.42, -21.53).

CONCLUSION

Collecting and analysing wristwatch IMU/GPS data using a commercially-available training platform was feasible in recreational runners.

Manipulating Internal and External Loads During Repeated Cycling Sprints: A Comparison of Continuous and Intermittent Blood Flow Restriction

ABSTRACT

Mckee, JR, Girard, O, Peiffer, JJ, and Scott, BR. Manipulating internal and external loads during repeated cycling sprints: A comparison of continuous and intermittent blood flow restriction. J Strength Cond Res 38(1): 47-54, 2024-This study examined the impact of blood flow restriction (BFR) application method (continuous vs. intermittent) during repeated-sprint exercise (RSE) on performance, physiological, and perceptual responses. Twelve adult male semi-professional Australian football players completed 4 RSE sessions (3 × [5 × 5-second maximal sprints:25-second passive recovery], 3-minute rest between the sets) with BFR applied continuously (C-BFR; excluding interset rest periods), intermittently during only sprints (I-BFR WORK ), or intraset rest periods (I-BFR REST ) or not at all (Non-BFR). An alpha level of p < 0.05 was used to determine significance. Mean power output was greater for Non-BFR (  p < 0.001, dz = 1.58 ), I-BFR WORK (  p = 0.002, dz = 0.63 ), and I-BFR REST (  p = 0.003, dz = 0.69 ) than for C-BFR and for Non-BFR (  p = 0.043, dz = 0.55 ) compared with I-BFR REST . Blood lactate concentration (  p = 0.166) did not differ between the conditions. Mean oxygen consumption was higher during Non-BFR (  p < 0.001, dz = 1.29 and 2.31; respectively) and I-BFR WORK ( p < 0.001, dz = 0.74 and 1.63; respectively) than during I-BFR REST and C-BFR and for I-BFR REST (  p = 0.002, dz = 0.57) compared with C-BFR. Ratings of perceived exertion were greater for I-BFR REST (  p = 0.042, dz = 0.51) and C-BFR (  p = 0.011, dz = 0.90) than for Non-BFR and during C-BFR (  p = 0.023, dz = 0.54) compared with I-BFR WORK . Applying C-BFR or I-BFR REST reduced mechanical output and cardiorespiratory demands of RSE and were perceived as more difficult. Practitioners should be aware that BFR application method influences internal and external demands during RSE.

Reduced Match Exposure in the Previous 2 Matches Accounts for Hamstring Muscle Injury Incidence in Professional Football Players

BACKGROUND

Hamstring strain injuries are one of the most prevalent injuries in football (soccer). We examined the influence of accumulated match-play exposure on the occurrence of hamstring strain injury in professional football from 2 teams (Spanish 1st Division, LaLiga) over 3 seasons, and determined specific cut-off points as indicators of injury risk.

HYPOTHESIS

Overloaded players would be more likely to sustain a hamstring injury.

STUDY DESIGN

Prospective, controlled, observational study.

LEVEL OF EVIDENCE

Level 2b.

METHODS

Playing time, total running distance, and high-speed running (>24 km/h) distance during official matches of players that sustained a hamstring injury were compared with uninjured, paired controls. Cumulative playing time and running performance of 4 matches before the injury was computed. Relative risk (RR) of injury occurrence was estimated by generalized estimating equations. Diagnostic accuracy was determined by receiver operating characteristics and the area under the curve.

RESULTS

Thirty-seven hamstring strain injuries occurred, representing 23 ± 18 absence days per injury. Thirty-seven controls (uninjured players) were used as comparators. Low match-play exposures during 1 and 2 matches before injury were likely to explain injury occurrence (RR: 14-53%; P < 0.01). Metrics from the match before the hamstring muscle strain demonstrated the best accuracy to predict injury occurrence: high-speed running distance ≤328 m (sensitivity, 64%; specificity, 84%), playing time ≤64 min (sensitivity, 36%; specificity, 97%), and running distance ≤5.8 km (sensitivity, 39%; specificity, 97%).

CONCLUSION

Relatively reduced competitive exposure in the previous 2 matches was associated with higher hamstring injury risk in professional football players.

CLINICAL RELEVANCE

Screening simple metrics such as the accumulated match exposure during official matches and considering specific cut-off points for some running variables may be good indicators of injury risk and may assist in better individual injury management in professional soccer players.

Quantification of daily workload, energy expenditure, and sleep of US Marine recruits throughout a 10-week boot camp

BACKGROUND

During periods of high-volume vigorous exercise, United States Marine Corps recruits often experience musculoskeletal injuries. While the program of instruction (POI) for basic training is a defined training volume, the total workload of boot camp, including movements around the base, is unknown.

OBJECTIVE

The present study aimed to quantify the daily total workload, energy expenditure, and sleep during basic recruit training at Marine Corps Recruit Depot (MCRD) San Diego.

METHODS

Eighty-four male recruits from MCRD San Diego wore wrist wearable physiological monitors to capture their complete workload (mileage from steps), energy expenditure, and sleep throughout the 10-week boot camp.

RESULTS

Marine recruits traveled an average of 11.5±3.4 miles per day (M±SD), expended 4105±823 kcal per day, and slept an average of 5 : 48±1 : 06 hours and minutes per night. While the POI designates a total of 46.3 miles of running and hiking, the actual daily average miles yielded approximately 657.6±107.2 miles over the 10-week boot camp.

CONCLUSION

Recruit training requires high physical demand and time under tension due to the cumulative volume of movements around base in addition to the POI planned physical training.

Overuse Injuries, Overtraining, and Burnout in Young Athletes

Sports participation can have tremendous physical and mental health benefits for children. Properly implemented progressive training programs can yield a broad range of beneficial physiologic adaptations, but imbalances of training load and recovery can have important negative consequences. Overuse injuries, for example, can result from repetitive stress without sufficient recovery that leads to accumulated musculoskeletal damage. In addition, extended periods of increased training loads that exceed the intervening recovery can have systemic consequences such as overtraining syndrome, which results in decreased performance, increased injury and illness risk, and derangement of endocrine, neurologic, cardiovascular, and psychological systems. Burnout represents one of the primary reasons for attrition in youth sports. Broadly defined as physical or mental exhaustion and a reduced sense of accomplishment that leads to devaluation of sport, burnout represents a direct threat to the goal of lifelong physical activity and the wide-ranging health benefits that it provides. This clinical report is intended to provide pediatricians with information regarding the risk factors, diagnosis, management, and prevention of these conditions to assist in the identification of at-risk children, the treatment of young athletes, and the guidance of families in the promotion of safe and healthy sport participation.

Weekly Training Load Differences between Starting and Non-Starting Soccer Players

The aim of this study was to examine the differences in the weekly training load between starters and non-starters classified based on the match starting line-up, with respect to the playing position and a training day. Notably, 31 young adult soccer players (age: 18.79 ± 1.04 years) competing in the 3rd Czech division were monitored across the season. The weekly training load was measured using a GPS system as follows: total distance covered (TD), high-speed running distance (HSR), sprint running distance (SR), and acceleration and deceleration distance (ACDC). We found higher values in three out of four observed variables (HSR, SR, and ACDC, excluding TD) for starters compared to non-starters (p < 0.05), with small to moderate effect sizes (d = 0.40-0.49). Differences were observed especially in players who were fullbacks, offensive midfielders, and forwards. Moreover, the largest differences were found in training prior to a match day for HSR, SR, and ACDC (p < 0.05). Non-starters experienced lower weekly external loads in offensive player positions, predominantly in high-intensity variables, which are essential for their physical performance. It seems that non-starters may experience potential under-loading in the training process. Coaches and practitioners should be aware of this potential risk and find an appropriate method to compensate for load discrepancies, particularly in terms of high-intensity activities.

A new statistical approach to training load and injury risk: separating the acute from the chronic load

The relationship between recent (acute) training load relative to long-term (chronic) training load may be associated with sports injury risk. We explored the potential for modelling acute and chronic loads separately to address current statistical methodology limitations. We also determined whether there was any evidence of an interaction in the association between acute and chronic training loads and injury risk in football. A men's Qatar Stars League football cohort (1 465 players, 1 977 injuries), where training load was defined as the number of minutes of activity, and a Norwegian elite U-19 football cohort (81 players, 60 injuries), where training load was defined as the session rating of perceived exertion (sRPE). Mixed logistic regression was run with training load on the current day (acute load) and cumulative past training load estimated by distributed lag non-linear models (chronic load) as independent variables. Injury was the outcome. An interaction between acute and chronic training load was modelled. In both football populations, we observed that the risk of injury on the current day for different values of acute training load was highest for players with low chronic load, followed by high and then medium chronic load. The slopes varied substantially between different levels of chronic training load, indicating an interaction. Modelling acute and chronic loads separately in regression models is a suitable statistical approach for analysing the association between relative training load and injury risk in injury prevention research. Sports scientists should also consider the potential for interactions between acute and chronic load.

Female Athletes and the Menstrual Cycle in Team Sports: Current State of Play and Considerations for Future Research

Over the past ten years there has been a dramatic rise in female sport participation and accompanying female professional national leagues across multiple sports, yet research has not followed suit. Although there are known variations between female and male physiology, training protocols in female sport are predominantly underpinned by research undertaken in male athletes. The hormonal variability experienced by women across the menstrual cycle, as well as the menstrual cycle variability between women, may contribute to the complexity of conducting rigorous physiological studies, leading to a paucity of robust sports-specific research that can be confidently applied to female athletes. Moreover, barriers exist in female sport that potentially limit the ability to conduct research, including the lack of full-time programs and limited resources. Recently, there has been increased interest in the potential effects of fluctuations in the female sex hormones, progesterone and oestrogen, on sport performance across different phases of the menstrual cycle. However, current research evaluating the menstrual cycle and physical performance (such as strength, speed, aerobic fitness, and athletes' perception of their performance) have shown inconsistent results. Additionally, methodological design across studies has shown little consistency, making it difficult to draw firm conclusions, which potentially prevents female athletes optimising their physical and sporting performance. It further impacts coaches and sports science researchers in their ability to provide appropriate training recommendations and educational opportunities. It is important to progress in female athlete research with an understanding of how the unique physiology of female athletes may influence their ability to physically perform in their respective sport, which requires representation in sports science research. This paper will provide an overview on current evidence and limitations within menstrual cycle research and provide considerations and directions for future research in this space within team sports.

Is a Maximal Strength-Training Program Effective on Physical Fitness, Injury Incidence, and Injury Burden in Semi-Professional Soccer Players? A Randomized Controlled Trial

The aims of the study were to analyze the effects of a 12-week maximal strength- training program on injury incidence, injury burden, and physical fitness in semi-professional soccer players and to compare the perceived exertion load and well-being state between injured and non-injured soccer players. Twenty semi-professional male soccer players participated in this study. Participants were randomly allocated to an experimental group (EG, n = 10 players), who performed a maximal strength-training program, or to a control group (CG, n = 10 players), who only performed their regular soccer training. Physical fitness was measured at baseline and after the training program. In addition, the injury incidence, burden, training/match load, and the state of well-being of the players were recorded. The EG showed significant improvements in vertical jumps, change in direction ability, linear sprints, repeated sprint ability, isometric strength (p < 0.003; effect size = 1.78-11.86), and quadriceps-hamstring imbalance in both legs (p < 0.001; effect size = 2.37-3.71) in comparison to the CG. In addition, the EG players showed a significantly (p < 0.05) lower injury burden (p < 0.001, relative risk = 5.05, 95% confidence interval = 3.27-7.79). This study demonstrated the beneficial effects of a 12-week maximal strength-training program on physical fitness attributes and injury burden in semi-professional soccer players.

A novel approach for sports injury risk prediction: based on time-series image encoding and deep learning

The rapid development of big data technology and artificial intelligence has provided a new perspective on sports injury prevention. Although data-driven algorithms have achieved some valuable results in the field of sports injury risk assessment, the lack of sufficient generalization of models and the inability to automate feature extraction have made it challenging to deploy research results in the real world. Therefore, this study attempts to build an injury risk prediction model using a combination of time-series image encoding and deep learning algorithms to address this issue better. This study used the time-series image encoding approach for feature construction to represent relationships between values at different moments, including Gramian Angular Summation Field (GASF), Gramian Angular Difference Field (GADF), Markov Transition Field (MTF), and Recurrence Plot (RP). Deep Convolutional Auto-Encoder (DCAE) learned the image-encoded data for representation to obtain features with good discrimination, and the classifier was performed using Deep Neural Network (DNN). The results from five repeated experiments show that the GASF-DCAE-DNN model is overall better in the training (AUC: 0.985 ± 0.001, Gmean: 0.930 ± 0.007, Sensitivity: 0.997 ± 0.003, Specificity: 0.868 ± 0.013) and test sets (AUC: 0.891 ± 0.026, Gmean: 0.830 ± 0.027, Sensitivity: 0.816 ± 0.039, Specificity: 0.845 ± 0.022), with good discriminative power, robustness, and generalization ability. Compared with the best model reported in the literature, the AUC, Gmean, Sensitivity, and Specificity of the GASF-DCAE-DNN model were higher by 23.9%, 27.5%, 39.7%, and 16.2%, respectively, which confirmed the validity and practicability of the model in injury risk prediction. In addition, differences in injury risk patterns between the training and test sets were identified through shapley additivity interpretation. It was also found that the training volume was an essential factor that affected injury risk prediction. The model proposed in this study provides a powerful injury risk prediction tool for future sports injury prevention practice.

Monitoring load, wellness, and psychological variables in female and male youth national team football players during international and domestic playing periods

Aim

To study differences in total load exposure, wellness, and psychological variables in youth female (N = 19) and male (N = 20) national team football players during domestic and international playing periods, respectively.

Procedures

The players filled out questionnaires on well-being, stress, and resilience before and after both playing periods lasting 8 days each. The Hooper index was used to monitor daily wellness levels during both playing periods. The number of training sessions and matches were recorded, and the session rating of perceived exertion was collected. Training load, monotony, and strain were calculated. Daily measurements were used to evaluate in-period changes, and composite scores were used to describe differences between periods.

Results

The international compared to the domestic playing period was for both groups characterized by more matches played, longer field training session durations, and of fewer gym-based sessions (P < 0.05). The male players increased total exposure time (25%; P < 0.05), monotony (P < 0.001), and strain (P < 0.001), which was not changed in the female players. Well-being decreased (P < 0.05) during the international playing period in male players. Stress levels were higher (P < 0.05) for both genders during the international compared to the domestic playing period. During the international playing period, positive correlations were found between the initial levels of stress, and the change in stress (P = 0.03; r2 = 0.12), and between the changes in total load and changes in well-being (P = 0.02; r2 = 0.12), whereas a negative correlation was found between the changes in wellness and stress (P = 0.03; r2 = 0.14).

Conclusion

A playing period characterized by increased match focus, longer field training sessions, and fewer gym-based training activities may lead to changes in the physical and mental profiles of youth national team football players. Alterations to load exposure and wellness may influence mental health. Players with high initial stress levels may be subjected to greater changes compared to other players. Sports scientists and medical staff may benefit from initiating structured monitoring systems to track alterations in physical load and mental health in youth national team players.

Risk factors and injury prevention strategies for overuse injuries in adult climbers: a systematic review

Introduction

Climbing is an increasingly popular activity and imposes specific physiological demands on the human body, which results in unique injury presentations. Of particular concern are overuse injuries (non-traumatic injuries). These injuries tend to present in the upper body and might be preventable with adequate knowledge of risk factors which could inform about injury prevention strategies. Research in this area has recently emerged but has yet to be synthesized comprehensively. Therefore, the aim of this study was to conduct a systematic review of the potential risk factors and injury prevention strategies for overuse injuries in adult climbers.

Methods

This systematic review was conducted in accordance with the PRISMA guidelines. Databases were searched systematically, and articles were deemed eligible based upon specific criteria. Research included was original and peer-reviewed, involving climbers, and published in English, German or Czech. Outcomes included overuse injury, and at least one or more variable indicating potential risk factors or injury prevention strategies. The methodological quality of the included studies was assessed with the Downs and Black Quality Index. Data were extracted from included studies and reported descriptively for population, climbing sport type, study design, injury definition and incidence/prevalence, risk factors, and injury prevention strategies.

Results

Out of 1,183 records, a total of 34 studies were included in the final analysis. Higher climbing intensity, bouldering, reduced grip/finger strength, use of a "crimp" grip, and previous injury were associated with an increased risk of overuse injury. Additionally, a strength training intervention prevented shoulder and elbow injuries. BMI/body weight, warm up/cool downs, stretching, taping and hydration were not associated with risk of overuse injury. The evidence for the risk factors of training volume, age/years of climbing experience, and sex was conflicting.

Discussion

This review presents several risk factors which appear to increase the risk of overuse injury in climbers. Strength and conditioning, load management, and climbing technique could be targeted in injury prevention programs, to enhance the health and wellbeing of climbing athletes. Further research is required to investigate the conflicting findings reported across included studies, and to investigate the effectiveness of injury prevention programs.

Systematic Review Registration

https://www.crd.york.ac.uk/, PROSPERO (CRD42023404031).

A Finger in the Game: Sport-Specific Finger Strength Training and Onset of Injury

INTRODUCTION

Strength training has proved to be an effective way to prevent injuries, but the evidence of the impact of strength training on finger injuries is lacking. A fingerboard is a sport-specific tool used by climbers for strength training of fingers. In this study, we searched for associations between fingerboard training and finger injuries in climbers with different lengths of climbing experience and levels of performance.

METHODS

A web-based survey was used to collect information on self-perceived pain or injury in fingers (SPIIF) and regular fingerboard training (RFT). The survey was administered to the Finnish climbing community. Data were analyzed using contingency tables; chi-square was used to evaluate statistical significance.

RESULTS

No significant correlations between SPIIF and RFT were found when analyzing all the participants (n=434) together. In climbers with 6 y or more in the sport, SPIIF was not common and RFT was negatively associated with SPIIF (χ2 [1, n=200]=4.57; P=0.03). In contrast to this, in male climbers who had been climbing for less than 6 y and had advanced to 7a level or higher (French lead/Font bouldering), SPIIF was common and RFT was positively associated with SPIIF (χ2 [1, n=75]=4.61; P=0.03).

CONCLUSIONS

We suggest that doing RFT may prevent SPIIF in climbers with a long background in the sport as fingerboard training can help build stronger fingers and thereby stronger tendons and ligaments. Climbers with fewer years in the sport and less adaptation to the fingers should be cautious with their training loads and RFT to avoid finger injuries and pain.

Female Soccer Periodization on Anaerobic Power/Capacity

ABSTRACT

Purdom, TM, Levers, KS, Ryan, GA, Brown, L, Giles, J, and McPherson, C. Female soccer periodization on anaerobic power/capacity. J Strength Cond Res 37(12): 2405-2410, 2023-The purpose of this study was to observe changes in anaerobic power and capacity (resistance to fatigue) over an annual training cycle (ATC) in 14 Division I female soccer athletes (19.4 ± 1.0 years, 60.8 ± 5.4 kg, 164.9 ± 6.2 cm, 19.5 ± 3.2% body fat, and 48.9 ± 3.9 kg fat free mass). All subjects were evaluated across the ATC at 5 testing blocks (B1-B5) representing seasonal transitions: postcompetition I (B1), prespring (B2), postspring training (B3), precompetition (B4), and postcompetition II (B5) using 3 tests: countermovement vertical jump to measure peak vertical power (PVP), 40-yard sprint to measure peak horizontal power (PHP), and 35-m running anaerobic sprint test to measure anaerobic capacity via fatigue index (FI). Repeated measures analysis of variance was used with the Bonferroni post hoc test when relevant along with Cohen's d to evaluate effect size. Data are represented as mean ± SD ; significance set to p < 0.05. Significant performance increases were observed from postseason I to spring season training (B1-B3) in PVP (6.61 ± 3.18 and 7.71 ± 3.20; p < 0.01, d = 1.12) while changes occurred from prespring season to postspring season (B2-B3) in PVP (6.84 ± 3.15 and 7.71 ± 3.20; p = 0.03, d = 0.93) and PHP (6.65 ± 0.97 and 7.55 ± 1.26; p < 0.01, d = 1.06) with no change in body composition. No other significant changes were observed across the ATC ( p > 0.05). Increases in PHP and PVP occurred with directed training after B3 and then declined remaining so across the competitive season. Peak horizontal power and PVP may be more sensitive to coaching style and seasonal transition compared with FI and body composition changes.