Development of novel calibration model(s) to predict whole-body density in professional football players

INTRODUCTION

Questions continue to be raised about the validity that is in existence to estimate Db, in professional male footballer players.

METHODS

Phase 1: n = 28 anthropometric variables were used on n = 206 footballers, using regression analyses to determine standard error of estimate and R2. A cut-off correlation coefficient set at r = 0.950 and 90% R2. Phase 2: all variables (z-scores, x -  = 0.0, SD = ±1.0) to help reduce heteroscedasticity, β, r, t, significance of t and P-values were calculated. Phase 3: a forced stepwise-backwards regression analysis approach with nine predictors which met the acceptance criteria (r = 0.950, R2 = 90% and β weights) was used to develop a 'best fit' and a 'practical' calibration model. Phase 4: cross-validation of the two newly developed calibration method using LoA.

RESULTS

The 'best fit' model SEM (0.115 g ml-1), the highest R2 (6.6%) (P  ≤ 0.005), whereas the 'practical' calibration model SEM (0.115 g ml-1), R2 (4.7%) (P  ≤ 0.005) with r values = 0.271 and 0.596 and R2 (%) coefficients = 0.3526 for the 'best fit' and 'practical' calibration models, respectively (P = 0.01).

CONCLUSIONS

The two calibration models supported an ecologically and statistically valid contribution and can provide sound judgements about professional footballers' body composition.

Relationships influencing organisational culture in men's elite football clubs in Norway

This paper examines the relationships within and outside organisations that have the leverage to influence culture in the context of men's elite football clubs in Norway. Participants from three clubs held positions as Performance Director (n=2), sport psychology practitioner (n = 3), and physiotherapist (n = 2) and participated in semi-structured interviews focusing on the relationships, tensions, and dynamic organisational forces in their respective clubs. Using reflexive thematic analysis, we developed two overarching themes showing (1) Organisational cultures in time frames and (2) Relationships among stakeholders influencing organisational culture. Developing these themes indicated that an organisational culture is not only a point of arrival, but also a point of departure for future activities. Hence, those charged with organisational culture work must maintain awareness of the influence of a club's history and how it influences dynamic tensions with stakeholders within and outside clubs. It is also critical that cultural practitioners are mindful of players' and staffs' individual journeys, which influence how they self-organise into fluid and temporary subgroups. The findings can sharpen our understanding of working with culture in elite football by emphasising other sources of culture besides leaders' attempts at controlling or steering it in their preferred way. Using the findings provided in this study can help practitioners recognise organisational tensions or slippage towards cultural problems before they lead to traumatic organisational crises.

Analysis of football research trends using text network analysis

This study was aimed to identify football research trends in various periods. A total of 30,946 football papers were collected from a representative academic database and search engine, the 'Web of Science'. Keyword refinement included filtering nouns, establishing synonyms and thesaurus, and excluding conjunctions, and the Cyram's Netminer 4.0 software was used for network analysis. A centrality analysis was conducted by extracting the words corresponding to the top 2% of the main research topics to obtain the degree and eigenvector centralities. The most frequently mentioned research keywords were injury, performance, and club. Keyword performance showed the highest degree centrality (0.294) and keyword world and cup showed the highest eigenvector centrality (0.710). The keyword with the highest eigenvector degree changed from injury in the 1990s and world in the 2000s to cup since the 2010s. Although various studies on football injuries have been conducted, research on the sport itself has recently been conducted. This study provides fundamental information on football trends from research published over the past 30 years.

Arabic translation and cultural adaptation of a training load and player monitoring in high-level football questionnaire: A cognitive interview study

BACKGROUND

Understanding the current practice and the associated challenges in applying monitoring tools is essential to improving football performance in the Middle East, thus the purpose was to translate and culturally adapt a published questionnaire that assessed the practice and perception of High-Level football teams toward Training Load and Player Monitoring to be used in the Arabic context, aiming to contribute to the enhancement of football performance, player welfare, and training quality in the region.

METHOD

A total of 15 Arabic-speaking coaches (mean age 42.6 ± 9.9 years; mean experience 10.9 ± 5.7 years; 53.3% football coaches and 46.7% strength & conditioning coaches) were conveniently selected to participate in this study. The current research followed a systematic cross-cultural adaptation process, which included forward translation, synthesis, back-translation, expert panel review, and pre-testing through cognitive interviewing. Three rounds of cognitive interviews were conducted with the 15 participants. Descriptive statistics, including means with standard deviations and frequencies with percentages, were reported for the participants' characteristics.

RESULT

With some minor linguistic modifications to the questionnaire by the expert committee (i.e., adjustments such as Sport Scientist to Sport Science Specialist), the instrument was translated and culturally adapted into Arabic. All participants confirmed that the resulting Arabic versions of the training load and player monitoring in high-level football questionnaires were appropriate and fully understandable for Arabic speakers in conveying the intended meanings of the items in each.

CONCLUSION

The training load and player monitoring in the high-level football questionnaire was successfully translated and culturally adapted into Arabic and are now ready for use in the Arabic context, offering an opportunity for comprehensive research and enabling tailored performance optimization strategies, which could ultimately lead to advancements in player development and welfare within Arabic-speaking football communities.

Linking Type and Extent of Head Trauma to Cavum Septum Pellucidum in Older Adults With and Without Alzheimer Disease and Related Dementias

BACKGROUND AND OBJECTIVES

Cavum septum pellucidum (CSP) is a common but nonspecific MRI finding in individuals with prior head trauma. The type and extent of head trauma related to CSP, CSP features specific to head trauma, and the impact of brain atrophy on CSP are unknown. We evaluated CSP cross-sectionally and longitudinally in healthy and clinically impaired older adults who underwent detailed lifetime head trauma characterization.

METHODS

This is an observational cohort study of University of California, San Francisco Memory and Aging Center participants (healthy controls [HCs], those with Alzheimer disease or related dementias [ADRDs], subset with traumatic encephalopathy syndrome [TES]). We characterized traumatic brain injury (TBI) and repetitive head impacts (RHI) through contact/collision sports. Study groups were no RHI/TBI, prior TBI only, prior RHI only, and prior RHI + TBI. We additionally looked within TBI (1, 2, or 3+) and RHI (1-4, 5-10, and 11+ years). All underwent baseline MRI, and 67% completed a second MRI (median follow-up = 5.4 years). CSP measures included grade (0-4) and length (millimeters). Groups were compared on likelihood of CSP (logistic regression, odds ratios [ORs]) and whether CSP length discriminated groups (area under the curve [AUC]).

RESULTS

Our sample included 266 participants (N = 160 HCs, N = 106 with ADRD or TES; age 66.8 ± 8.2 years, 45.3% female). Overall, 123 (49.8%) participants had no RHI/TBI, 52 (21.1%) had TBI only, 41 (16.6%) had RHI only, 31 (12.6%) had RHI + TBI, and 20 were classified as those with TES (7.5%). Compared with no RHI/TBI, RHI + TBI (OR 3.11 [1.23-7.88]) and TES (OR 11.6 [2.46-54.8]) had greater odds of CSP. Approximately 5-10 years (OR 2.96 [1.13-7.77]) and 11+ years of RHI (OR 3.14 [1.06-9.31]) had higher odds of CSP. CSP length modestly discriminated participants with 5-10 years (AUC 0.63 [0.51-0.75]) and 11+ years of prior RHI (AUC 0.69 [0.55-0.84]) from no RHI/TBI (cut point = 6 mm). Strongest effects were noted in analyses of American football participation. Longitudinally, CSP grade was unchanged in 165 (91.7%), and length was unchanged in 171 (95.5%) participants.

DISCUSSION

Among older adults with and without neurodegenerative disease, risk of CSP is driven more by duration (years) of RHI, especially American football, than number of TBI. CSP length (≥6 mm) is relatively specific to individuals who have had substantial prior RHI. Neurodegenerative disease and progressive atrophy do not clearly influence development or worsening of CSP.

The Frequency and Severity of Gastrointestinal Symptoms in Rugby Players

This study aimed to assess the self-reported frequency and severity of gastrointestinal symptoms (GIS) at rest and around rugby training and match play in male and female rugby union players. An online questionnaire was sent to registered rugby union players (sevens or fifteens). Thirteen GIS were assessed alongside perceptions of appetite around rugby and rest using Likert and visual analog scales. Questions investigating a range of medical and dietary factors were included. Three hundred and twenty-five players (male n=271, female n=54) participated in the study. More frequent GIS (at least one GIS experienced weekly/more often) was reported by players at rest (n=203; 62%) compared to around rugby (n=154; 47%). The overall severity of GIS was low (mild discomfort), but a portion of players (33%) did report symptoms of moderate severity around rugby. Female players reported more frequent and severe symptoms compared to male counterparts (p<0.001). Self-reported appetite was significantly lower after matches compared to training. There were no dietary or medical factors associated with GIS severity scores. This study describes GIS characteristics in male and female rugby union players. Half of the players assessed experienced some form of GIS that may affect nutrition, training, or performance, and should thus be a consideration for practitioners supporting this cohort.

Predicting adolescents' continuation in club sports: A prospective cohort study of the importance of personal and contextual motivational factors in five sports in Denmark

PURPOSE

The purpose of this prospective cohort study was to investigate the influence of types of motivation, basic psychological needs satisfaction and of a coach-created motivational climate on continued participation in youth sports across types of sport, competitive levels, ages, and gender.

METHODS

Participants were 7110 adolescent (age 12-20 years) members of leisure time club organized in basketball, handball, football, badminton, and gymnastics in Denmark. Motivational regulation was measured with BRSQ-6, basic psychological needs satisfaction and frustration were measured with PNSS-S, and coach-created climate was measured with the EDMCQ-C. The participants' continuation or dropout was measured at the beginning of the following season with a short electronic questionnaire.

RESULTS

Intrinsic motivation, identified behavior regulation, experiences of competence, relatedness, and autonomy, as well as a coach-created empowering motivational climate, were associated with continuation both in the sport and in the club the following season across different sports, genders, age groups, and competitive levels. Introjected and external behavior regulation, frustrations with the need to experience competence, relatedness, and autonomy, as well as a disempowering coach-created climate, were associated with dropout.

CONCLUSION

In Danish youth sports, autonomous motivation, satisfaction of basic psychological needs, and an empowering coach-created motivational climate have a positive impact on the continuation of the sport and the club the following season. In contrast, controlled types of motivation, needs frustration, and a disempowering coach-created climate are associated with dropout. This is the case at both elite and recreational levels, for boys and girls, adolescents, and youth.

Aerodynamic investigation of the inrun position in Ski jumping

This study aims to investigate the inrun position in ski-jumping, in search for factors increasing the inrun speed without compromising the take-off. The inrun position of eight World Cup (WC) and fifteen Continental Cup (COC) ski jumpers were investigated in a wind tunnel at NTNU. A preferred position, replicating a jumper's position in competition, was measured for each athlete. Improvements, based on common sense aerodynamics, with the aim to improve the aerodynamic drag were executed. The aerodynamically best of these was compared with the preferred position. A numerical model simulating the inrun speed in ski-jumping hills was used to evaluate the impact the results will have in different hill sizes, for comparisons of drag measurements and inrun speed in competitions. In the preferred position, COC had 15.5% higher drag area than the WC athletes. In their best tested position, a group difference of 10.8% was found. These differences correspond with speed differences between 0.4 and 1.3 kmh-1, or 1-3 gates (as found by the numerical model). Group difference in drag was explained by a larger trunk angle for COC. Both groups improved from their preferred to their best position, due to reductions in thigh and leg angle.

Mass gathering in Qatar 2022 World Cup. What should be especially monitored?

OBJECTIVES

At the end of 2022, the football world championship will be held in Qatar. These types of meetings require a risk analysis. It proposes an approach to determine which health risks should be prioritized.

METHOD

We use a mixed methodology (Hierarchical Process Analysis, World Health Organization STAR and European Commission INFORM) to determine the risk level of a total of 12 health entities.

RESULTS

Our analysis identifies 6 health entities with a moderate risk. There are 4 whose valuation is as low risk and 2 as very low.

CONCLUSIONS

In our work we focus the analysis from a point of view of the route of transmission or presentation of health events, which facilitates a visualization of the preventive measures to be implemented, both organizationally and individually by the attendees.

Position-specific workload of professional rugby union players during tactical periodization training

The positional workload characteristics in rugby union on three acquisition days (i.e. strength, endurance, and speed days) of tactical periodization are still relatively unknown. Therefore, the primary aim of this study was to shed light on the positional external workload variables (10 Hz Global Positioning System and accelerometer microtechnology) and internal workload indicators (the session rating of perceived exertion) of players in a professional rugby union team by utilizing and comparing two tactical periodization models. Twenty-six male players (15 forwards and 11 backs) were recruited from a French second-division rugby club. Data were obtained over 10 weeks of in-season home games: a total of 780 observations were analyzed. Student's t-test observed different external workload profiles between positions among acquisition days. Mean external workload values, except PlayerLoadslow, were significantly higher (p≤0.01; effect size: 0.41-1.93) for backs than forwards for all acquisition days. Moreover, forwards perceived a higher internal workload than backs on the strength day of both models. The findings demonstrate that applying these two tactical periodization models could result in effective rugby union training. Validating external and internal workload characteristics on tactical periodization acquisition days enables extensive analysis of training load monitoring data; these data can be utilized to discover the unique characteristics of each position and design position-specific acquisition days to improve performance.

AI-based betting anomaly detection system to ensure fairness in sports and prevent illegal gambling

This study develops a solution to sports match-fixing using various machine-learning models to detect match-fixing anomalies, based on betting odds. We use five models to distinguish between normal and abnormal matches: logistic regression (LR), random forest (RF), support vector machine (SVM), the k-nearest neighbor (KNN) classification, and the ensemble model-a model optimized from the previous four. The models classify normal and abnormal matches by learning their patterns using sports betting odds data. The database was developed based on the world football league match betting data of 12 betting companies, which offered a vast collection of data on players, teams, game schedules, and league rankings for football matches. We develop an abnormal match detection model based on the data analysis results of each model, using the match result dividend data. We then use data from real-time matches and apply the five models to construct a system capable of detecting match-fixing in real time. The RF, KNN, and ensemble models recorded a high accuracy, over 92%, whereas the LR and SVM models were approximately 80% accurate. In comparison, previous studies have used a single model to examine football match betting odds data, with an accuracy of 70-80%.

The Inclusion of Preplanned and Random and Unanticipated/Unexpected Events During Strength Training Improves the Ability to Repeat High-Intensity Efforts Under Uncertainty

PURPOSE

To compare the effects of unilateral flywheel training (FT), using a rotational conical pulley, including multidirectional movements with either preplanned or random unanticipated/unexpected executions on functional performance in football players.

METHODS

A total of 32 young male football players were randomly assigned to an FT program including preplanned unilateral multidirectional movements (PTG, n = 11), an FT executing the same unilateral movements through random (ie, right or left leg) unanticipated (ie, verbal or visual cue) or unexpected (ie, moment where the cue was provided) situations (UTG, n = 11), or a control group (n = 10) that followed their football training routine. FT consisted of 1 set × 5-12 repetitions of 4 exercises performed once a week for 10 weeks. Intermittent endurance performance, repeated unilateral and bilateral jumping ability, change-of-direction (COD) ability, linear sprint velocity, preplanned repeated-sprint ability (RSA), and uncertainty RSA (RSA-RANDOM) were assessed preintervention and postintervention.

RESULTS

Significant improvements were found in RSA-RANDOM performance (P < .05, effect size [ES] range: UTG [1.83-2.16], PTG [0.69-0.73]) and COD (P < .05, ES: UTG = 1.34, PTG = 0.98]) in both training groups. Furthermore, significant improvements were also found in intermittent endurance performance (P = .016, ES = 0.37) and sprinting (P = .006, ES = 0.45) in UTG. No changes in any variable were found in the control group. No significant between-groups differences (P > .05) were reported between UTG and PTG, while differences were observed to the control group in unilateral jumping ability, COD, and RSA-RANDOM for UTG, and in RSA-RANDOM for PTG.

CONCLUSIONS

A 10-week unilateral FT improved RSA-RANDOM and COD ability in youth football players, so both preplanned and unexpected situations should be included on strength training.

Knowledge and Attitudes of Concussion Reporting Behavior Intentions in Parents of Youth Recreational Football Players

Purpose: This study: (1) Described the knowledge, attitudes, and reported behavior intentions of young recreational football players' parents toward concussion. (2) Investigated associations of the previous variables with parent demographics. Materials and Methods: A cross-sectional design utilized an online platform to survey parents of children (8-14 yrs.) in three youth football leagues in the southern United States. Demographics collected included items such as sex or concussion history. Knowledge was assessed via true/false items, with higher scores (0-20) representing greater concussion understanding. 4-point Likert scales were used to describe parents attitudes (1 = not at all, 4 = very much), confidence in intended recognition/reporting (1 = not-confident, 4 = extremely confident), and agreement with intended reporting behaviors (1 = strong- disagreement, 4 = strong-agreement). Descriptive statistics were calculated for demographics. Mann-Whitney U test or Kruskal-Wallis Tests examined survey responses across demographics. Results: Respondents (n = 101) were primarily female (64.4%), white (81.2%), and participated in contact sport (83.2%). Parents averaged 15.9 ± 1.4 on concussion knowledge, with only 34.7% (n = 35) of parents scoring > 17/20. Statements that received the lowest average agreement (3.29/4) regarding reporting intent were related to emotional symptoms. Some parents (n = 42, 41.6%) reported low confidence in recognizing symptoms of a concussion in their child. Parent demographics did not have clinically significant associations with survey responses, with 6/7 demographic variables resulting in no statistical significance (p > .05). Conclusions: Although one-third of parents attained high knowledge scores, several reported low confidence in recognizing concussion symptoms in their children. Parents scored lower in agreement with removing their child from play when concussion symptoms were subjective. Youth sports organizations providing concussion education to parents should consider these results when revising their materials.

Quantifying Offense and Defense Workloads in Professional Rugby Union

PURPOSE

Rugby union is a contact team sport demanding high levels of physical capacity, and understanding the match workloads can be useful to inform training. In this study, the factors influencing locomotion and contact workloads for offensive and defensive ball-in-play periods are quantified.

METHODS

Locomotion and contact metrics were collected from global positioning system units and videos for 31 professional players of a Super Rugby team across 14 games in the 2021 season. Data were analyzed with a generalized mixed-model procedure that included effects for type of play, playing position, match outcome, and ball-in-play time. Magnitudes were assessed with standardization, and evidence for substantial magnitudes was derived from sampling uncertainty.

RESULTS

When offense was compared to defense, most metrics showed decisively substantial increases (small to moderate) for forwards and backs. There was decisive evidence that locomotion metrics were substantially lower (large differences) and contact metrics were higher (very large differences) when comparing forwards to backs on offense and defense. When winning was compared to losing, there was good evidence that forwards experienced small increases in overall workload on defense, and backs experienced a small increase in high-speed running and a moderate decrease in contacts on offense. Match-to-match changes associated with ball-in-play time, attributed to fatigue, were decisive (moderate to very large) across most metrics for forwards and backs in offense and defense.

CONCLUSIONS

The increased locomotion and contact workloads in offensive periods and the differing physical requirements between positions and match outcomes for both types of play are novel findings that should aid practitioners in designing effective training.

Examination of parkinsonism in former elite American football players

BACKGROUND

Former American football players are at risk for chronic traumatic encephalopathy (CTE) which may have parkinsonism as a clinical feature.

OBJECTIVE

Former football players were prospectively assessed for parkinsonism.

METHODS

120 former professional football players, 58 former college football players, and 60 same-age asymptomatic men without repetitive head impacts, 45-74 years, were studied using the MDS-UPDRS to assess for parkinsonism, and the Timed Up and Go (TUG). Traumatic encephalopathy syndrome (TES), the clinical syndrome of CTE, was adjudicated and includes parkinsonism diagnosis. Fisher's Exact Test compared groups on parkinsonism due to small cell sizes; analysis of covariance or linear regressions controlling for age and body mass index were used otherwise.

RESULTS

Twenty-two (12.4%) football players (13.3% professional, 10.3% college) met parkinsonism criteria compared with two (3.3%) in the unexposed group. Parkinsonism was higher in professional (p = 0.037) but not college players (p = 0.16). There were no differences on the MDS-UPDRS Part III total scores. Scores on the individual MDS-UPDRS items were low. TUG times were longer in former professional but not college players compared with unexposed men (13.09 versus 11.35 s, p < 0.01). There were no associations between years of football, age of first exposure, position or level of play on motor outcomes. TES status was not associated with motor outcomes.

CONCLUSIONS

Parkinsonism rates in this sample of football players was low and highest in the professional football players. The association between football and parkinsonism is inconclusive and depends on factors related to sample selection, comparison groups, and exposure characteristics.

Differences in physical activity volume and intensity between Unified and non-Unified Special Olympics football training: An observational pilot study

BACKGROUND

The participation of people with intellectual disabilities in Special Olympics sports and training opportunities offers numerous benefits for health and inclusion. However, little is known about the impact of such training on physical activity behaviour. Here, we evaluate the differences in physical activity volume and intensity of Special Olympics athletes between Unified and non-Unified football training.

METHOD

Accelerometer data of 12 male athletes from eight standardised training sessions (four Unified, four non-Unified) were analysed.

RESULTS

While there was no statistically significant difference for the main part of the training, athletes showed higher levels of physical activity intensity (MVPA: Mdiff  = 11.74%; 95% CI = 5.50-17.97) and volume (average acceleration ENMO: Mdiff  = 112.82 mg; 95% CI = 24.73-200.90) in a Unified compared to non-Unified endurance-related exercise task.

CONCLUSION

Understanding physical activity participation in different training types can help to design and implement future training programmes.

Effects of a Strength and Conditioning Offseason Program on Countermovement Jump Ground Reaction Forces in Division I American Football Players

ABSTRACT

Gillen, ZM, Burch, RF, Saucier, DN, Strawderman, L, Luczak, T, Piroli, A, Petway, AJ, and Rath, T. Effects of a strength and conditioning offseason program on countermovement jump ground reaction forces in Division I American football players. J Strength Cond Res 38(3): e86-e95, 2024-The purpose of this study was to examine the effects of a 10-week strength and conditioning offseason program on the ground reaction forces (GRFs) of American football players during single-leg and double-leg countermovement jumps (SLJ and CMJ, respectively). Each subject visited the laboratory twice, once for preoffseason and once for postoffseason testing. During each visit, subjects performed CMJs and SLJs for each leg. Ground reaction forces were collected by force plates to quantify unweighting, braking, propulsive, and performance metrics for each jump. In addition, an efficiency index was calculated for each jump to examine changes in vertical jump efficiency. Dependent samples t tests compared all CMJ metrics. Two-way repeated measures analyses of variance (leg × time) compared all SLJ metrics. An alpha level of p ≤ 0.05 was considered statistically significant. For the CMJ, propulsive phase duration decreased due to the program ( p = 0.007), whereas peak braking power, peak propulsive power, mean propulsive force, and jump height increased ( p ≤ 0.012). For the SLJ, peak braking power, force at the low position, braking rate of force development, eccentric force, peak propulsive power, mean propulsive force, and jump height increased in both legs ( p ≤ 0.044). The efficiency index increased for the CMJ and the SLJ for both legs ( p ≤ 0.016). This study demonstrated that SLJ and CMJ vertical jump performance significantly increases in as few as 10 weeks of offseason strength and conditioning. Strength and conditioning programming may effectively increase vertical jump performance, as assessed by GRFs, which can be used as a simple indicator regarding changes in athletic performance.

A Profile of Isometric Cervical Strength in Elite Professional Male Rugby Players

OBJECTIVES: To (1) provide position-specific normative data for isometric cervical muscle strength and endurance in professional, male rugby players and (2) assess the relationship between age, height, weight, and playing position with cervical muscle strength and endurance. DESIGN: Cross-sectional study. METHODS: Professional rugby players completed peak isometric cervical strength testing followed by a test of cervical muscle endurance. Descriptive statistics for continuous variables with strength normalized to body weight were performed. Multiple linear regression was used to estimate associations between strength measurements. RESULTS: In total, 136 players participated including front-row forwards (27%), other forwards (28%), and backs (45%). Front-row forwards had significantly greater peak isometric cervical muscle strength than other position groups, with backs having the lowest strength. Extension produced the highest force for all 3 position groups (429 N ± 104 N), whereas flexion produced the least (275 N ± 65 N). Age was associated with increased isometric cervical muscle strength. There was a statistically significant relationship between peak flexion strength and flexion endurance (P = .003). The average time for the endurance tests were 55.7 (±17.1) seconds and 52.9 (±20.1) seconds for extension and flexion, respectively. Other forwards had lower cervical extension muscle endurance than backs and front-row forwards. CONCLUSIONS: Normative values for peak and endurance isometric strength in professional rugby players illustrate significant differences between playing position. Consider age, body weight, and intraindividual variability when interpreting cervical strength and endurance results. J Orthop Sports Phys Ther 2024;54(3):1-8. Epub 29 January 2024. doi:10.2519/jospt.2024.11830.

Referee Abuse, Intention to Quit, and Well-Being

There are growing levels of abuse toward match officials in sport as well as general problems of their recruitment and retention. Purpose: This study analyzes the role that physical and nonphysical abuse has on association football referees' intentions to quit and their personal well-being. Methods: Drawing on pooled survey data of association football referees from the UK and Canada, this paper employs probit, ordinary least squares, and treatment effects regression analyses to explore the casual relationship between the physical and nonphysical abuse faced by referees, their intention to quit and their well-being. Results: Although physical abuse is less common than nonphysical abuse both affect the intention to quit and well-being of officials. Moreover, those that do not contemplate quitting also face reductions in their well-being. Conclusion: The research recommends a zero-tolerance approach to all forms of abuse of officials in sport and identifies that organizations have a duty of care for the well-being of their officials.

Outcomes and Proportions of Subsequent Contralateral Sports Hernia Repair Following Primary Unilateral Repair

BACKGROUND

In the event that nonoperative treatment for sports hernia fails, surgical repair may be warranted. Bilateral repair can occur in up to 45% of surgically treated patients.

PURPOSE

To investigate the clinical outcomes of athletes who underwent unilateral sports hernia repair and determine the proportion of patients who required contralateral sports hernia repair.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

We identified patients at our institution who underwent primary unilateral sports hernia repair (rectus abdominis-adductor longus aponeurotic plate repair and adductor lengthening) with a single surgeon between 2015 and 2020. We assessed patient-reported outcomes using the Hip Outcome Score-Sport (HOS-Sport), the Numeric Pain Rating Scale, and an internally developed return-to-play questionnaire. We further collected data regarding subsequent sports hernia procedures on the ipsilateral or contralateral side. We calculated summary statistics for outcomes and examined the association between preinjury patient characteristics and the HOS-Sport score at follow-up or successful return to preinjury sport using linear and logistic regression, respectively.

RESULTS

A total of 104 of 128 (81.3%) eligible patients (mean age at surgery, 23.0 ± 6.2 years; 94.2% male; 51.9% American football athletes) completed follow-up at a mean time of 4.4 ± 1.5 years. Overall, 79.8% of athletes (n = 83) were able to return to their preinjury sport/activity, but 90.2% (83/92) who attempted to return were able to do so. When examining reasons for not returning to preinjury sport, only 9 patients reported not returning to preinjury sport because of limitations or persistent symptoms from their original injury. Only 4 patients underwent subsequent sports hernia procedures (3 contralateral, 1 ipsilateral revision) after their index unilateral sports hernia repair. At follow-up, the mean HOS-Sport score was high (94.0 ± 10.8), and the mean Numeric Pain Rating Scale score was low (0.31 ± 1.26). There were no preinjury patient characteristics associated with either the HOS-Sport score at follow-up or the successful return to preinjury sport.

CONCLUSION

Patients with unilateral sports hernia symptoms can undergo repair and return to sport at the preinjury level with little concern for injuries to the contralateral groin. In our cohort, patient-reported hip function and pain outcomes at follow-up were excellent.

An eight-season analysis of the teams' performance in the Spanish LaLiga according to the final league ranking

This study aimed to analyse the performance of 5,518 collective observations of the Spanish LaLiga teams for eight consecutive seasons (from 2011-12 to 2018-19), considering the final league ranking. The teams were divided into four groups: Europe (from 1st to 6th), Upper-Middle (from 7th to 11th), Lower-Middle (from 12th to 17th) and Relegation (from 18th to 20th). The variables recorded were: Passes, Successful Passes, Crosses, Shots, Goals, Corners, Fouls, Width, Length, Height, distance from the goalkeeper to the nearest defender (GkDef), total distance covered (TD) and number of points accumulated. The main results were that: 1) Europe, being superior to the rest of the groups, showed lower values of Length from 2015-16, and lower values of GkDef from 2014-15; 2) Upper-Middle showed lower values of Length from 2015-16; 3) Lower-Middle showed fewer Shots from 2013-14, and lower values of Length, GkDef and TD from 2014-15; and, 4) Relegation barely showed significant differences between seasons in any variable. The study concludes that the teams of the Europe, Upper-Middle and Relegation groups showed quite stable performance, while the teams of the Lower-Middle group presented a worsening in different dimensions as the seasons progressed. The information provided in this study makes it possible to have reference values that have characterized the performance of the teams for each group.

Sporting tournaments and changed birth rates 9 months later: a systematic review

Introduction

Major sporting tournaments may be associated with increased birth rates 9 months afterwards, possibly due to celebratory sex. The influence of major sporting tournaments on birth patterns remains to be fully explored.

Methods

Studies that examined the relationship between such events and altered birth metrics (number of births and/or birth sex ratio (male/total live births)) 9(±1) months later were sought in PubMed and Scopus and reported via standard guidelines. Database searches were conducted up to 7 November 2022.

Results

Five events led to increased birth metrics 9(±1) months later and these included the Super Bowl, the 2009 UEFA Champions League, the 2010 FIFA World Cup, the 2016 UEFA Euros and the 2019 Rugby World Cup. Several la Liga soccer matches also had effects. With a few exceptions, major American football, Association football (soccer) and Rugby apex tournaments in Africa, North America, Asia and Europe were associated with increases in the number of babies born and/or in the birth sex ratio 9(±1) months following notable team wins and/or hosting the tournament. Furthermore, unexpected losses by teams from a premier soccer league were associated with a decline in births 9 months on.

Conclusions

This systematic review establishes that major sporting tournaments have a notable impact on birth patterns, influencing both birth rates and sex ratios. Emotional intensification during these events likely triggers hormonal shifts, driving changes in sexual activity and subsequently shaping birth rates, often positively, about 9 months later. The context is crucial, especially when a region/country hosts a major single-sport tournament or participates for the first time, as population excitement is likely to be at its peak. These findings hold significance for healthcare planning and highlight the role of societal events in shaping demographic trends.

PROSPERO registration

CRD42022382971.

Exploration of collective tactical variables in elite netball: An analysis of team and sub-group positioning behaviours

Collective tactical behaviours are aspects of player interactions that are particularly important in netball, due to its unique restrictions on player movement (players unable to move when in possession of the ball and positional spatial restrictions). The aim of this study was to explore variables representing collective tactical behaviours in netball. A local positioning system provided player positions of one team throughout seven elite-level netball matches. The positions were analysed to provide mean, variability (standard deviation) and irregularity (normalised approximate entropy) for each attack and defence possession (470 and 423, respectively) for the team and positional subgroups (forwards, midcourts and defenders) for 10 position-related variables. Correlational analyses showed collective tactical variables could be grouped as lateral and longitudinal dispersion variables. The variables were each analysed after log transformation with a linear mixed model to compare attack and defence and to estimate standardised effects on attack and defence of possession outcome, possession duration, score difference, match time, opposition strength and season time. During attack, the team and all sub-groups adopted greater lateral dispersion between players, while on defence there was generally greater longitudinal dispersion. The team also showed increased longitudinal dispersion when home and opposition possessions ended in a score. Additionally, greater irregularity was observed in active sub-groups (forwards on attack, defenders on defence). Score difference and opposition strength had trivial-small but generally unclear effects. In conclusion, these effects show that analysis of player positions on attack and defence is a promising avenue for coaches and analysts to modify collective tactical behaviours in netball.

Prevalence of hip femoroacetabular impingement deformities in high-level (La Liga) male professional football players

BACKGROUND

Femoroacetabular impingement (FAI) is considered one of the main causes of hip osteoarthritis in young adults, especially in athletes. In recent years, morphological changes in FAI in the hip have been linked to early and intense sports participation, but studying top-level athlete samples is not easy. This paper presents the prevalence of FAI radiological markers in 120 active white male professional football players in the Spanish First Division League (La Liga) and compares the morphological changes with those of a control group of healthy individuals without significant sport activity.

METHODS

The precontract medical evaluation hip X-rays of 120 white male professional football players from four different First Division Spanish football teams were prospectively filed and retrospectively reviewed by a dedicated skeletal radiologist. The footballers' hip X-rays were compared with those of a control group of 80 healthy individuals (age-sex matched) without significant sport activity (obtained from routine work medical checks).

RESULTS

The femoral head-neck deformity associated with the Cam type of femoroacetabular impingement was observed in 61.6% of professional football players and only in 11.6% of the control group (p <0.01). The presence of "herniation pit" (11.6%) and os acetabuli (13.3%) also reached statistical significance in the professional football players group. In the other analyzed parameters, no statistically significant differences between the groups were observed.

CONCLUSIONS

White professional top-level football players have an increased incidence of abnormal lateral epiphyseal extension ("pistol grip deformity"), os acetabuli and herniation pits.

The Longitudinal Relationship Between Concussion History, Years of American Football Participation, and Alcohol Use Among Former National Football League Players: an NFL-LONG Study

OBJECTIVE

Investigate the relationships between concussion history and years of football participation (repetitive head impact proxy) with alcohol use across multiple decades in former professional football players.

METHODS

Participants (n = 348; mean age = 49.0 ± 9.4) completed health questionnaires in 2001 and 2019, which included self-reported concussion history and years of participation. Alcohol use frequency and amount per occasion were reported for three timepoints: during professional career, 2001, and 2019. Ordinal logistic regression models were fit to test associations of concussion history and years of participation with alcohol use at each timepoint.

RESULTS

There were no significant associations between either concussion history or years of football participation with alcohol use (frequency and amount per occasion) at any timepoint. Effect estimates for concussion history and years of football participation with alcohol use were generally comparable across timepoints.

CONCLUSIONS

Later life alcohol use by former American football players is not associated with concussion history or years of exposure to football.

Inflammatory biomarkers for neurobehavioral dysregulation in former American football players: findings from the DIAGNOSE CTE Research Project

BACKGROUND

Traumatic encephalopathy syndrome (TES) is defined as the clinical manifestation of the neuropathological entity chronic traumatic encephalopathy (CTE). A core feature of TES is neurobehavioral dysregulation (NBD), a neuropsychiatric syndrome in repetitive head impact (RHI)-exposed individuals, characterized by a poor regulation of emotions/behavior. To discover biological correlates for NBD, we investigated the association between biomarkers of inflammation (interleukin (IL)-1β, IL-6, IL-8, IL-10, C-reactive protein (CRP), tumor necrosis factor (TNF)-α) in cerebrospinal fluid (CSF) and NBD symptoms in former American football players and unexposed individuals.

METHODS

Our cohort consisted of former American football players, with (n = 104) or without (n = 76) NBD diagnosis, as well as asymptomatic unexposed individuals (n = 55) from the DIAGNOSE CTE Research Project. Specific measures for NBD were derived (i.e., explosivity, emotional dyscontrol, impulsivity, affective lability, and a total NBD score) from a factor analysis of multiple self-report neuropsychiatric measures. Analyses of covariance tested differences in biomarker concentrations between the three groups. Within former football players, multivariable linear regression models assessed relationships among log-transformed inflammatory biomarkers, proxies for RHI exposure (total years of football, cumulative head impact index), and NBD factor scores, adjusted for relevant confounding variables. Sensitivity analyses tested (1) differences in age subgroups (< 60, ≥ 60 years); (2) whether associations could be identified with plasma inflammatory biomarkers; (3) associations between neurodegeneration and NBD, using plasma neurofilament light (NfL) chain protein; and (4) associations between biomarkers and cognitive performance to explore broader clinical symptoms related to TES.

RESULTS

CSF IL-6 was higher in former American football players with NBD diagnosis compared to players without NBD. Furthermore, elevated levels of CSF IL-6 were significantly associated with higher emotional dyscontrol, affective lability, impulsivity, and total NBD scores. In older football players, plasma NfL was associated with higher emotional dyscontrol and impulsivity, but also with worse executive function and processing speed. Proxies for RHI exposure were not significantly associated with biomarker concentrations.

CONCLUSION

Specific NBD symptoms in former American football players may result from multiple factors, including neuroinflammation and neurodegeneration. Future studies need to unravel the exact link between NBD and RHI exposure, including the role of other pathophysiological pathways.

Cerebral Cortical Surface Structure and Neural Activation Pattern Among Adolescent Football Players

Importance

Recurring exposure to head impacts in American football has garnered public and scientific attention, yet neurobiological associations in adolescent football players remain unclear.

Objective

To examine cortical structure and neurophysiological characteristics in adolescent football players.

Design, Setting, and Participants

This cohort study included adolescent football players and control athletes (swimming, cross country, and tennis) from 5 high school athletic programs, who were matched with age, sex (male), and school. Neuroimaging assessments were conducted May to July of the 2021 and 2022 seasons. Data were analyzed from February to November 2023.

Exposure

Playing tackle football or noncontact sports.

Main Outcomes and Measures

Structural magnetic resonance imaging (MRI) data were analyzed for cortical thickness, sulcal depth, and gyrification, and cortical surface-based resting state (RS)-functional MRI analyses examined the amplitude of low-frequency fluctuation (ALFF), regional homogeneity (ReHo), and RS-functional connectivity (RS-FC).

Results

Two-hundred seventy-five male participants (205 football players; mean [SD] age, 15.8 [1.2] years; 5 Asian [2.4%], 8 Black or African American [3.9%], and 189 White [92.2%]; 70 control participants; mean [SD] age 15.8 [1.2] years, 4 Asian [5.7], 1 Black or African American [1.4%], and 64 White [91.5%]) were included in this study. Relative to the control group, the football group showed significant cortical thinning, especially in fronto-occipital regions (eg, right precentral gyrus: t = -2.24; P = .01; left superior frontal gyrus: -2.42; P = .002). Elevated cortical thickness in football players was observed in the anterior and posterior cingulate cortex (eg, left posterior cingulate cortex: t = 2.28; P = .01; right caudal anterior cingulate cortex 3.01; P = .001). The football group had greater and deeper sulcal depth than the control groups in the cingulate cortex, precuneus, and precentral gyrus (eg, right inferior parietal lobule: t = 2.20; P = .004; right caudal anterior cingulate cortex: 4.30; P < .001). Significantly lower ALFF was detected in the frontal lobe and cingulate cortex of the football group (t = -3.66 to -4.92; P < .01), whereas elevated ALFF was observed in the occipital regions (calcarine and lingual gyrus, t = 3.20; P < .01). Similar to ALFF, football players exhibited lower ReHo in the precentral gyrus and medial aspects of the brain, such as precuneus, insula, and cingulum, whereas elevated ReHo was clustered in the occipitotemporal regions (t = 3.17; P < .001; to 4.32; P < .01). There was no group difference in RS-FC measures.

Conclusions and Relevance

In this study of adolescent athletes, there was evidence of discernible structural and physiological differences in the brains of adolescent football players compared with their noncontact controls. Many of the affected brain regions were associated with mental health well-being.

The role of the six factors model of athletic mental energy in mediating athletes' well-being in competitive sports

In the realm of high-performance sports, athletes often prioritize success at the expense of their well-being. Consequently, sports psychology researchers are now focusing on creating psychological profiles for athletes that can forecast their performance while safeguarding their overall well-being. A recent development in this field is the concept of athletic mental energy (AME), which has been associated with both sporting success and positive emotions. Therefore, the aim of this study was to explore if AME in athletes can mediate this directly observed relationship between performance and psychological well-being. For stronger predictive validity these relationships were examined across two studies with each involving distinct sets of participants engaged in various sports disciplines, including football, cricket, basketball, archery, and more. The self-report measures of sports performance, athletic mental energy (AME), and psychological well-being (PWB) were administered post-competition on the local, regional, state, national, international, and professional level athletes of age 18 and above. Our study found that both, the affective and cognitive components of AME mediated the athletes' performance and psychological well-being relationship. Interestingly, the study found no significant gender differences in AME and PWB scores. While family structures didn't yield significant variations in AME scores, there were some descriptive distinctions in PWB scores across different family structures. Our research offers preliminary evidence suggesting that AME can play a pivotal role in preserving athletes' psychological well-being following competitive events.

Different Aspects of Physical Load in Small-Sided Field Hockey Games

ABSTRACT

Wilmes, E, de Ruiter, CJ, van Leeuwen, RR, Banning, LF, van der Laan, D, and Savelsbergh, GJP. Different aspects of physical load in small-sided field hockey games. J Strength Cond Res 38(2): e56-e61, 2024-Running volumes and acceleration/deceleration load are known to vary with different formats of small-sided games (SSGs) in field hockey. However, little is known about other aspects of the physical load. Therefore, the aim of this study was to gain a more thorough understanding of the total physical load in field hockey SSGs. To that end, 2 different SSGs (small: 5 vs. 5, ∼100 m 2 per player; large: 9 vs. 9, ∼200 m 2 per player) were performed by 16 female elite field hockey athletes. A range of external physical load metrics was obtained using a global navigational satellite system and 3 wearable inertial measurement units on the thighs and pelvis. These metrics included distances covered in different velocity ranges (walk, jog, run, and sprint), mean absolute acceleration/deceleration, Hip Load, and time spent in several physically demanding body postures. The effects of SSG format on these external physical load metrics were assessed using linear mixed models ( p < 0.05). Running volumes in various speed ranges were higher for the large SSG. By contrast, mean absolute acceleration/deceleration and time spent in several demanding body postures were higher for the small SSG. This study shows that changing the SSG format affects different aspects of physical load differently.

Acute psychological symptom profiles in high school football players following sport-related concussion

OBJECTIVE

In a cohort of high school football athletes, the authors sought to 1) describe the proportion of those with acute psychological symptoms postconcussion, 2) determine predictors of more acute psychological symptoms postconcussion, and 3) determine if acute psychological symptoms impact recovery.

METHODS

A retrospective cohort study of high school football athletes (14-18 years of age) who sustained a sport-related concussion between November 2017 and April 2022 and presented to a multidisciplinary concussion center was performed. Based on their Post-Concussion Symptom Scale (PCSS) scores at the initial clinic visit, their total psychological symptom cluster score was calculated by summing their scores for the four affective symptoms (irritability, sadness, nervousness, and feeling more emotional). The psychological symptom ratio was defined as the ratio of the psychological symptom cluster score to the total initial PCSS score. Primary outcomes included time to return to learn (RTL), symptom resolution, and return to play (RTP). Uni- and multivariable regression analyses were performed controlling for demographic factors, learning disabilities, attention-deficit/hyperactivity disorder, and personal and/or family history of psychological diagnoses and migraine.

RESULTS

A total of 195 male football players (mean age 16.2 ± 1.2 years) were included in the study. About one-third of the sample (n = 70, 35.9%) reported at least one psychological symptom. Of these 70 athletes, their psychological symptom scores were 1 (10.3%), 2 (7.7%), and ≥ 3 (17.9%). Irritability was the most endorsed psychological symptom (25.1%), followed by nervousness (15.9%), feeling more emotional (12.8%), and sadness (11.8%). The multivariable regression model showed that a positive psychological history (B = 2.66, 95% CI 0.74-4.58, p = 0.007) and family psychological history (B = 2.43, 95% CI 0.98-3.88, p = 0.001) were significant predictors of a higher psychological symptom cluster score. Multivariable linear regression analysis showed that a higher psychological symptom cluster score was associated with a longer time to RTP (B = 1.22, 95% CI 0.17-2.264, p = 0.023) but not with time to symptom resolution or RTL. The psychological symptom ratio was not a significant predictor.

CONCLUSIONS

In a cohort of male football players, 36% reported at least one psychological symptom, with irritability being most commonly reported. Athletes with a personal and/or family history of psychological disorders experienced more acute psychological symptoms following a sport-related concussion. A higher psychological symptom cluster score was associated with delayed time to RTP but not time to RTL or symptom resolution.

Optimising classification in sport: a replication study using physical and technical-tactical performance indicators to classify competitive levels in rugby league match-play

  Determining key performance indicators and classifying players accurately between competitive levels is one of the classification challenges in sports analytics. A recent study applied Random Forest algorithm to identify important variables to classify rugby league players into academy and senior levels and achieved 82.0% and 67.5% accuracy for backs and forwards. However, the classification accuracy could be improved due to limitations in the existing method. Therefore, this study aimed to introduce and implement feature selection technique to identify key performance indicators in rugby league positional groups and assess the performances of six classification algorithms. Fifteen and fourteen of 157 performance indicators for backs and forwards were identified respectively as key performance indicators by the correlation-based feature selection method, with seven common indicators between the positional groups. Classification results show that models developed using the key performance indicators had improved performance for both positional groups than models developed using all performance indicators. 5-Nearest Neighbour produced the best classification accuracy for backs and forwards (accuracy = 85% and 77%) which is higher than the previous method's accuracies. When analysing classification questions in sport science, researchers are encouraged to evaluate multiple classification algorithms and a feature selection method should be considered for identifying key variables.

Profile of Athletes With a Vision Impairment: Exploring Demographics and Ocular Pathologies of Athletes in Three Paralympic Sports

OBJECTIVE

This study aimed to explore the profile of athletes with a vision impairment who compete in three Paralympic sports (goalball, vision impairment judo, and blind football).

DESIGN

Descriptive and association analyses of the vision impairment athletes' profile were conducted.

RESULTS

The typical athlete profile was a male (65.1%), aged 26-34 yrs (39.7%), from Europe (38.8%), representing a country with a high income (46.1%), and was diagnosed with a retinal-related ocular pathology (38.9%). In all three sports, the ages of the athletes were similar. In goalball, most athletes were from Europe, represented countries with a high income, and were diagnosed with retinal-, globe-, or neurological-related pathologies. In vision impairment judo, the majority of athletes were from Asia, represented countries with an upper middle income, and were diagnosed with retinal-, global-, or neurological-related pathologies. In blind football, most athletes were from Europe, represented countries with an upper middle income, and were diagnosed with retinal-, neurological-related ocular pathologies, or glaucoma.

CONCLUSIONS

The homogeneity of the athletes' profile suggests that an effort is needed to target other parts of the vision impairment population to take part in vision impairment sports. Differences in the athletes' profiles across the sports provide information that may be useful for sport-specific talent identification.

Prevalence of sports supplements consumption and its association with food choices among female elite football players

OBJECTIVES

The present study aimed to 1) investigate the consumption of Sports Supplements (SSs) among female elite football players, 2) evaluate the influence of age on SS consumption, and 3) determine the relationship between the consumption of SSs and dietary choices among elite football players.

METHODS

A total of 126 female football players of Primera Iberdrola and Reto Iberdrola who participated in this descriptive, observational, and cross-sectional study completed a self-administered questionnaire on SSs and the Athletes' Food Choices Questionnaire.

RESULTS

Overall, 84.1% of participants consumed supplements, mainly for improved sports performance (68.3%) and health (34.1%). The main sources of purchase were the Internet (34.9%) and specialized shops (23.8%), and players were commonly advised by a dietitian-nutritionist to use SSs (56.3%). The SSs most often consumed included whey protein (30.2%), sports drinks (28.6%), creatine monohydrate (28.6%), sports bars (27.8%), and caffeine (27.8%). Older players consumed more supplements at the time of data compilation. Players predominantly acquired these supplements by using the Internet and reported benefits from their use (all P ≤ 0.036). Additionally, players who consumed SSs conveyed more concern about their food choices.

CONCLUSIONS

A high prevalence of female football players consumed SSs, particularly SSs supported by robust scientific evidence. Older players had higher supplement consumption rates. The use of SSs was related to food choices through nutritional characteristics of foods, knowledge about health and nutrition, weight control with the help of food, and the performance benefits players could acquire.

An Analysis of Positional Generic and Individualized Speed Thresholds Within the Most Demanding Phases of Match Play in the English Premier League

OBJECTIVES

To analyze the positional distances covered above generic and individualized speed thresholds within the most demanding phases of match play. Categorized by position, 17 English Premier League players' match data were analyzed over 2 consecutive seasons (2019-20 and 2020-21). The most demanding phases of play were determined using a rolling average across 4 periods of 1, 3, 5, and 10 minutes. Distance covered in the time above the standard speed of 5.5 m/s was analyzed, with individualized metrics based on the maximal aerobic speed (MAS) test data.

RESULTS

Central defenders displayed lower values for high-intensity periods when compared with fullbacks, midfielders, and wide midfielders for both generic and individualized metrics. MAS during 1-minute periods was significantly higher for forwards when compared with central defenders (82.9 [18.9] vs 67.5 [14.8] for maximum high-speed running [HSR] and 96.0 [15.9] vs 75.7 [13.8] HSR for maximum MAS activity). The maximum effect size differences between the central midfielders, wide midfielders, and fullbacks for HSR and MAS measures under the maximum HSR criterion was 0.28 and 0.18 for the 1-minute period, 0.36 and 0.19 for the 3-minute period, 0.46 and 0.31 for the 5-minute period, and 0.49 and 0.315 for the 10-minute period.

CONCLUSIONS

Individualized speed metrics may provide a more precise and comparable measure than generic values. Data appear to be consistent across playing positions except for central defenders. This information may allow practitioners to directly compare individualized physical outputs of non-central defenders during the most demanding phases of play regardless of the players' positional group. This may provide coaches with important information regarding session design, training load, and fatigue monitoring.

Are volatile methylsiloxanes in downcycled tire microplastics? Levels and human exposure estimation in synthetic turf football fields

Downcycled rubber, derived from end-of-life tires (ELTs), is frequently applied as crumb rubber (CR) as infill of synthetic turf in sports facilities. This practice has been questioned in recent years as numerous studies have reported the presence of potentially hazardous chemicals in this material. CR particles fall into the category of microplastics (MPs), making them possible vectors for emerging micropollutants. A preliminary study where volatile methylsiloxanes (VMSs) were found in CR originated the hypothesis that VMSs are present in this material worldwide. Consequently, the present work evaluates for the first time the levels and trends of seven VMSs in CR from synthetic turf football fields, while attempting to identify the main sources and impacts of these chemicals. A total of 135 CR samples and 12 other of alternative materials were analyzed, employing an ultrasound-assisted dispersive solid-phase extraction followed by gas chromatography-mass spectrometry (GC-MS), and the presence of VMSs was confirmed in all samples, in total concentrations ranging from 1.60 to 5089 ng.g-1. The levels were higher in commercial CR (before field application), a reflection of the use of VMS-containing additives in tire production and/or the degradation of silicone polymers employed in vehicles. The VMSs generally decreased over time on the turf, as expected given their volatile nature and the wearing of the material. Finally, the human exposure doses to VMSs in CR (by dermal absorption and ingestion) for people in contact with synthetic turf in football fields were negligible (maximum total exposure of 20.5 ng.kgBW-1.year-1) in comparison with the European Chemicals Agency (ECHA) reference doses: 1.35 × 109 ng.kgBW-1.year-1 for D4 and 1.83 × 109 ng.kgBW-1.year-1 for D5. Nevertheless, more knowledge on exposure through inhalation and the combined effects of all substances is necessary to provide further corroboration. This work proved the presence of VMSs in CR from ELTs, another family of chemical of concern to take into account when studying MPs as vectors of other contaminants.

The current state of concussion knowledge and attitudes in British American Football

OBJECTIVES

To examine concussion knowledge and concussion attitudes of players, coaches, and support staff in British American Football (BAF).

METHODS

Data from players, coaches and support staff (n = 236) were collected from across all leagues in BAF. An online survey tool was used which included the Rosenbaum Concussion Knowledge and Attitudes Survey (RoCKAS), and questions examining concussion education and perceived risk of participating in football.

RESULTS

The mean score on the RoCKAS concussion knowledge was 21.0 ± 2.1 of a possible score of 25 reflecting good knowledge. Of a possible score of 65, the mean concussion attitude score was 55.6 ± 6.1 showing safe attitude. Whilst an overall safe attitude was seen, almost half of participants (45.3%) noted they would continue to play with a concussion. No relationship was found between CAI and prior concussion history. Fifty seven percent of participants agreed the benefits of playing football outweighed the risks. Forty eight percent reported that they had received no concussion-related education in the past 12 months.

CONCLUSION

BAF participants have good concussion knowledge and safe attitudes. However, risky behavior is demonstrated through unsafe likelihood to report and attitude to long-term health risks. Access to the British American Football Association (BAFA) concussion policy and education was poor raising questions over what sources of information stakeholders are drawing their knowledge from. These findings can help form the foundation of educational interventions (e.g. coaching workshops) to challenge current misconceptions and improve likelihood to report concussion in BAF.

Mechanical and metabolic power in accelerated running-Part II: team sports

PURPOSE

This manuscript is devoted to discuss the interplay between velocity and acceleration in setting metabolic and mechanical power in team sports.

METHODS

To this aim, an essential step is to assess the individual Acceleration-Speed Profile (ASP) by appropriately analysing training sessions or matches. This allows one to estimate maximal mechanical and metabolic power, including that for running at constant speed, and hence to determine individual thresholds thereof.

RESULTS

Several approaches are described and the results, as obtained from 38 official matches of one team (Italian Serie B, season 2020-2021), are reported and discussed. The number of events in which the external mechanical power exceeded 80% of that estimated from the subject's ASP ([Formula: see text]) was 1.61 times larger than the number of accelerations above 2.5 m s-2 ([Formula: see text]). The difference was largest for midfielders and smallest for attackers (2.30 and 1.36 times, respectively) due to (i) a higher starting velocity for midfielders and (ii) a higher external peak power for attackers in performing [Formula: see text]. From the energetic perspective, the duration and the corresponding metabolic power of high-demanding phases ([Formula: see text]) were essentially constant (6 s and 22 W  kg-1, respectively) from the beginning to the end of the match, even if their number decreased from 28 in the first to 21 in the last 15-min period, as a consequence of the increased recovery time between [Formula: see text] from 26 s in the first to 37 s in the last 15-min period.

CONCLUSION

These data underline the flaws of acceleration counting above fixed thresholds.

Mechanical characterization of athletic helmet shells

Our purpose was to compare the mechanical properties of the protective outer shells of various athletic helmets in their final, fully manufactured form. Sections were taken from 3 different helmet shells (Bauer RE-AKT hockey helmet, Cascade R lacrosse helmet, and Riddell Speedflex football helmet) at 4 different locations (front, side, top, and rear) for a total of 12 test specimens. The 4 specimens from each helmet shell were potted together in epoxy resin moulds and mechanically polished. The hardness, elastic modulus and phase angle were measured using dynamic nanoindentation performed at 100 Hz with an oscillation amplitude of 1 nm (rms). Repeated ANOVA analysis was used to compare each of the dependent variables for each of the 3 helmets across the 4 different locations. The interaction between helmet type and location was significant for hardness (F6,63 = 2.84, P = 0.032, Pη2 = 0.21), elastic modulus (F6,63 = 6.412, P < 0.001, Pη2 = 0.38), and phase angle (F6,63 = 7.65, P < 0.001, Pη2 = 0.42). Polycarbonate has a higher ability to dissipate mechanical energy making it the recommended superior choice for helmet shells. In addition, the results lead us to speculate that manufacturing causes changes in the molecular weight or the distribution of fillers across locations for polyethylene but not for polycarbonate since mechanical properties are fairly uniform over the surface of football helmets, at least within a given helmet.

Deceleration Profiles Between the Penultimate and Final Steps of Planned and Reactive Side-Step Cutting

CONTEXT

Noncontact anterior cruciate ligament injury often occurs during rapid deceleration and change-of-direction maneuvers. These activities require an athlete to generate braking forces to slow down the center of mass and change direction in a dynamic environment. During preplanned cutting, athletes can use the penultimate step for braking before changing direction, resulting in less braking demand during the final step. During reactive cutting, athletes use different preparatory movement strategies during the penultimate step when planning time is limited. However, possible differences in the deceleration profile between the penultimate and final steps of preplanned and reactive side-step cuts remain unknown.

OBJECTIVE

To comprehensively evaluate deceleration during the penultimate and final steps of preplanned and reactive cutting.

DESIGN

Cross-sectional study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Thirty-six women (age = 20.9 ± 1.7 years, height = 1.66 ± 0.07 m, mass = 62.4 ± 8.7 kg).

INTERVENTION

Participants completed 90° side-step cutting maneuvers under preplanned and reactive conditions.

MAIN OUTCOME MEASURE(S)

Approach velocity, velocity at initial contact, and cutting angle were compared between conditions. Stance time, deceleration time, and biomechanical indicators of deceleration were assessed during the penultimate and final steps of preplanned and reactive 90° cuts. Separate repeated-measures analysis-of-variance models were used to assess the influence of step, condition, and their interaction on the biomechanical indicators of deceleration.

RESULTS

Approach velocity (P = .69) and velocity at initial contact of the penultimate step (P = .33) did not differ between conditions. During reactive cutting, participants achieved a smaller cutting angle (P < .001). We identified a significant step-by-condition interaction for all biomechanical indicators of deceleration (P values < .05).

CONCLUSIONS

A lack of planning time resulted in less penultimate step braking and greater final step braking during reactive cutting. As a result, participants exhibited a decreased cutting angle and longer stance time during the final step of reactive cutting. Improving an athlete's ability to respond to an external stimulus may facilitate a more effective penultimate step braking strategy that decreases the braking demand during the final step of reactive cutting.

Load monitoring, strength training, and recovery in futsal: Practitioners' perspectives

This study aimed to describe the current practices in futsal regarding a variety of topics related to performance and injury risk mitigation. Thirty-seven coaches from Spain and Portugal completed a questionnaire consisting of 28 closed questions organized in four categories: a) background information; b) training load (TL) monitoring and assessment of players' physical qualities; c) strength training (ST) practices; and d) recovery (REC) methods. The results showed that coaches varied in experience (1-8 years) and age (from 20 years to >50 years). Overall, 97.3% of the participants declared monitoring TL, with rating of perceived exertion, heart rate monitors, and wearable technology being used by 86.5%, 40.5%, and 37.8%, respectively. Neuromuscular and strength testing are the most common practices to evaluate performance and fatigue during the season. ST is a significant component of futsal, being performed 3 times/week during the pre- and in-season. ST is prescribed via %1RM - XRM (59.5%), velocity-based training (21.7%), repetitions in reserve (18.9%), until failure (10.8%), and circuit training (2.7%). 'Better Monitoring', 'More Individualized', 'Better Facilities', 'More Staff', and 'More Time' were the main aspects to improve ST. Multiple post-match REC strategies are used, with durations ranging from 0-15 to 16-30 min independently of game location.

Match-play movement demands of international and domestic women's rugby sevens players in an elite dual-level tournament

OBJECTIVES

To characterize and compare match-play movement demands via Global Positioning Systems (GPS) between international and domestic women's rugby sevens players performing in a novel elite dual-level tournament, with consideration to position and tournament characteristics.

DESIGN

Fifty-four rugby sevens players; twenty-one international(5 speed edges, 8 backs, 8 forwards), and thirty-three domestic(10 speed edges, 11 backs, 12 forwards) wore GPS devices during an elite dual-level tournament covering 2 seasons, with 367 full match-play data files analysed. Internationaland domestic players were distributed evenly between competing teams.

METHODS

Match-play movement demands were characterized by distance, speed, and acceleration-based indices from 5 to 10 Hz GPS devices.

RESULTS

International players recorded significantly higher high-intensity match-play movement demands compared to domestic players in distance in high and very high-speed zones (P = 0.01, P = 0.03, P = 0.01, P = 0.03), maximal acceleration (P = 0.001), maximal velocity (P < .001), speed exertion (P = 0.01),       , and acceleration load density (P = 0.03)   . Positional analysis demonstrated forwards displayed the largest significant differences between international and domestic players. . Total and relative match-play movement demands of the dual-leveltournament also showed comparable demands to previous international tournament research .

CONCLUSIONS

Results identify key points of difference in match-play movement demands between player levels in women's rugby sevens, and provides important information on the characteristics of playing positions, and of a dual-level tournament of this nature. This will improve the design and implementation of structures from domestic to international level.

Head Acceleration Events in Male Community Rugby Players: An Observational Cohort Study across Four Playing Grades, from Under-13 to Senior Men

OBJECTIVES

The aim of this study was to examine the cumulative head acceleration event (HAE) exposure in male rugby players from the Under-13 (U13) to senior club level over 4 weeks of matches and training during the 2021 community rugby season.

METHODS

This prospective, observational cohort study involved 328 male rugby players. Players were representative of four playing grades: U13 (N = 60, age 12.5 ± 0.6 years), U15 (N = 100, age 14.8 ± 0.9 years), U19 (N = 78, age 16.9 ± 0.7 years) and Premier senior men (N = 97, age 22.5 ± 3.1 years). HAE exposure was tracked across 48 matches and 113 training sessions. HAEs were recorded using boil-and-bite instrumented mouthguards (iMGs). The study assessed the incidence and prevalence of HAEs by ages, playing positions, and session types (match or training).

RESULTS

For all age grades, weekly match HAE incidence was highest at lower magnitudes (10-29 g). Proportionally, younger players experienced higher weekly incidence rates during training. The U19 players had 1.36 times the risk of high-magnitude (> 30 g) events during matches, while the U13 players had the lowest risk compared with all other grades. Tackles and rucks accounted for the largest HAE burden during matches, with forwards having 1.67 times the risk of > 30 g HAEs in rucks compared with backs.

CONCLUSIONS

This study provides novel data on head accelerations during rugby matches and training. The findings have important implications for identifying populations at greatest risk of high cumulative and acute head acceleration. Findings may guide training load management and teaching of skill execution in high-risk activities, particularly for younger players who may be exposed to proportionally more contact during training and for older players during matches.

Changing gears: data-driven velocity zones to support monitoring and research in men's rugby league

OBJECTIVES

The study aimed to (1) apply a data-mining approach to league-wide microtechnology data to identify absolute velocity zone thresholds and (2) apply the respective velocity zones to microtechnology data to examine the locomotor demands of elite match-play.

METHODS

League-wide microtechnology data were collected from elite male rugby league players representing all National Rugby League (NRL) teams (n = 16 teams, one excluded due to a different microtechnology device; n = 4836 files) over one season. To identify four velocity zones, spectral clustering with a beta smoothing cut-off of 0.1 was applied to each players' instantaneous match-play velocity data. Velocity zones for each player were calculated as the median while the overarching velocity zones were determined through an incremental search to minimise root mean square error.

RESULTS

The velocity zones identified through spectral clustering were 0-13.99 km · h-1 (i.e., low velocity), 14.00-20.99 km · h-1 (i.e., moderate velocity), 21.00-24.49 km · h-1 (i.e., high velocity) and >24.50 km · h-1 (i.e., very-high velocity).

CONCLUSIONS

The application of spectral clustering (i.e., a data-mining method) to league-wide rugby league microtechnology data yielded insights into the distribution of velocity data, thereby informing the cut-off values which best place similar data points into the same velocity zones. As the identified zones are representative of the intensities of locomotion achieved by elite male rugby league players, it is suggested that when absolute zones are used, the consistent application of the identified zones would facilitate standardisation, longitudinal athlete monitoring as well as comparisons between teams, leagues and published literature.

The influence of tactical formation on physical and technical performance across playing positions in the Chinese super league

This study aimed to investigate the impact of tactical formations on the physical and technical performance of professional football players in the Chinese Super League (CSL). A sample of 800 games from the 2015-2021 CSL was analyzed, and players' physical (total distance covered, distance covered while ball in play, number of sprints, sprint distance, and high/middle/low-speed running) and technical (gain/loss of possession, ball retention percentage, challenges, challenge success percentage, passes, and pass success percentage) performance was assessed across six team formations: 3-5-2 (n = 137), 4-3-3 (n = 77), 4-2-3-1 (n = 391), 4-4-2 (n = 257), 3-4-3 (n = 41), and 4-1-4-1 (n = 107). Linear mixed models were used to assess variations in performance indicators across positions and formations. The results demonstrated that central defenders traveled significantly more total and low-speed running distances in the 3-5-2 formation than in the 4-2-3-1 formation (ES range: 0.33-0.34, p < 0.01). Fullbacks in the 3-5-2 formation demonstrated more high-speed running than did those in the 4-4-2 formation (ES = 0.27, p = 0.04). The central midfielders exhibited significantly more sprints and longer sprint distances in the 4-2-3-1 formation than in the 4-4-2 formation (ES range: 0.2-0.24, p < 0.01). Regarding technical performance, central defenders displayed significantly greater ball retention percentages, passes, and pass success rates in the 3-4-3 than in the 3-5-2 formations (ES range: 0.58-0.65, p < 0.01). Moreover, fullbacks and central midfielders executed markedly more passes with superior pass success rates in 4-back formations than in 3-5-2 formations (ES range: 0.2-0.53, p < 0.01). These findings can help coaches and academic staff understand the physical and technical requirements of various positions in various tactical formations, thus optimizing the training process.

Motivation and goal-pursuit for injury prevention training in amateur football coaches: a cross-sectional study using the Health Action Process Approach

BACKGROUND

Adoption of injury prevention exercise programmes (IPEPs) in team sports is contingent on behaviour change among coaches. The aim was to study motivation and goal-pursuit in IPEP use among coaches of amateur football players.

METHODS

A cross-sectional study using web-based questionnaires was administered to coaches in one Swedish regional football district. The study was carried out one season after dissemination of the IPEP Knee Control+. The questionnaire was based on the Health Action Process Approach and covered perceptions and beliefs about using Knee Control+. Questions were rated on 1-7 Likert scales.

RESULTS

440 coaches participated (response rate 32%). Coaches were neutral about injury risks (median 4-5) and knowledge about preventing injuries (median 5) but had positive outcome expectancies of preventive training (median 6). Coaches who had used an IPEP perceived they had more knowledge about preventing injuries than non-users (median 5 vs 4, small effect size d=0.43). Coaches who used Knee Control+ were positive about their practical ability to use it (median 6) and had high intention to prioritise continuous use (median 7). Highly adherent coaches to higher extent believed that specific training may prevent injuries and had plans for how to instruct the players and how to work around barriers compared with low adherent coaches.

CONCLUSION

Coaches need more knowledge and support on IPEP usage and how to structure training. Coaches who had adopted Knee Control+ had high belief in their abilities but may need constructive plans on how to use the programme and to overcome barriers.

Association of Vascular Risk Factors and CSF and Imaging Biomarkers With White Matter Hyperintensities in Former American Football Players

BACKGROUND AND OBJECTIVES

Recent data link exposure to repetitive head impacts (RHIs) from American football with increased white matter hyperintensity (WMH) burden. WMH might have unique characteristics in the context of RHI beyond vascular risk and normal aging processes. We evaluated biological correlates of WMH in former American football players, including markers of amyloid, tau, inflammation, axonal injury, neurodegeneration, and vascular health.

METHODS

Participants underwent clinical interviews, MRI, and lumbar puncture as part of the Diagnostics, Imaging, and Genetics Network for the Objective Study and Evaluation of Chronic Traumatic Encephalopathy Research Project. Structural equation modeling tested direct and indirect effects between log-transformed total fluid-attenuated inversion recovery (FLAIR) lesion volumes (TLV) and the revised Framingham stroke risk profile (rFSRP), MRI-derived global metrics of cortical thickness and fractional anisotropy (FA), and CSF levels of amyloid β1-42, p-tau181, soluble triggering receptor expressed on myeloid cells 2 (sTREM2), and neurofilament light. Covariates included age, race, education, body mass index, APOE ε4 carrier status, and evaluation site. Models were performed separately for former football players and a control group of asymptomatic men unexposed to RHI.

RESULTS

In 180 former football players (mean age = 57.2, 36% Black), higher log(TLV) had direct associations with the following: higher rFSRP score (B = 0.26, 95% CI 0.07-0.40), higher p-tau181 (B = 0.17, 95% CI 0.01-0.43), lower FA (B = -0.28, 95% CI -0.42 to -0.13), and reduced cortical thickness (B = -0.25, 95% CI -0.45 to -0.08). In 60 asymptomatic unexposed men (mean age = 59.3, 40% Black), there were no direct effects on log(TLV) (rFSRP: B = -0.03, 95% CI -0.48 to 0.57; p-tau181: B = -0.30, 95% CI -1.14 to 0.37; FA: B = -0.07, 95% CI -0.48 to 0.42; or cortical thickness: B = -0.28, 95% CI -0.64 to 0.10). The former football players showed stronger associations between log(TLV) and rFSRP (1,069% difference in estimates), p-tau181 (158%), and FA (287%) than the unexposed men.

DISCUSSION

Risk factors and biological correlates of WMH differed between former American football players and asymptomatic unexposed men. In addition to vascular health, p-tau181 and diffusion tensor imaging indices of white matter integrity showed stronger associations with WMH in the former football players. FLAIR WMH may have specific risk factors and pathologic underpinnings in RHI-exposed individuals.

Longitudinal changes in resting state fMRI brain self-similarity of asymptomatic high school American football athletes

American football has become the focus of numerous studies highlighting a growing concern that cumulative exposure to repetitive, sports-related head acceleration events (HAEs) may have negative consequences for brain health, even in the absence of a diagnosed concussion. In this longitudinal study, brain functional connectivity was analyzed in a cohort of high school American football athletes over a single play season and compared against participants in non-collision high school sports. Football athletes underwent four resting-state functional magnetic resonance imaging sessions: once before (pre-season), twice during (in-season), and once 34-80 days after the contact activities play season ended (post-season). For each imaging session, functional connectomes (FCs) were computed for each athlete and compared across sessions using a metric reflecting the (self) similarity between two FCs. HAEs were monitored during all practices and games throughout the season using head-mounted sensors. Relative to the pre-season scan session, football athletes exhibited decreased FC self-similarity at the later in-season session, with apparent recovery of self-similarity by the time of the post-season session. In addition, both within and post-season self-similarity was correlated with cumulative exposure to head acceleration events. These results suggest that repetitive exposure to HAEs produces alterations in functional brain connectivity and highlight the necessity of collision-free recovery periods for football athletes.