Higher shoe-surface interaction is associated with doubling of lower extremity injury risk in football codes: a systematic review and meta-analysis

Using a Bayesian network to classify time to return to sport based on football injury epidemiological data

The return-to-sport (RTS) process is multifaceted and complex, as multiple variables may interact and influence the time to RTS. These variables include intrinsic factors related the player, such as anthropometrics and playing position, or extrinsic factors, such as competitive pressure. Providing an individualised estimation of time to return to play is often challenging, and clinical decision support tools are not common in sports medicine. This study uses epidemiological data to demonstrate a Bayesian Network (BN). We applied a BN that integrated clinical, non-clinical factors, and expert knowledge to classify time day to RTS and injury severity (minimal, mild, moderate and severe) for individual players. Retrospective injury data of 3374 player seasons and 6143 time-loss injuries from seven seasons of the professional German football league (Bundesliga, 2014/2015 through 2020/2021) were collected from public databases and media resources. A total of twelve variables from three categories (player's characteristics and anthropometrics, match information and injury information) were included. The response variables were 1) days to RTS (1-3, 4-7, 8-14, 15-28, 29-60, > 60, and 2) injury severity (minimal, mild, moderate, and severe). The sensitivity of the model for days to RTS was 0.24-0.97, while for severity categories it was 0.73-1.00. The user's accuracy of the model for days to RTS was 0.52-0.83, while for severity categories, it was 0.67-1.00. The BN can help to integrate different data types to model the probability of an outcome, such as days to return to sport. In our study, the BN may support coaches and players in 1) predicting days to RTS given an injury, 2) team planning via assessment of scenarios based on players' characteristics and injury risk, and 3) understanding the relationships between injury risk factors and RTS. This study demonstrates the how a Bayesian network may aid clinical decision making for RTS.

Injury risk profile for soccer players: identification of the risk factors for soccer-related injuries - an umbrella review

This review aimed to identify risk factors for soccer injuries and provide researchers the needed elements to build a soccer-player's injury risk profile. An umbrella review was conducted following the PRIOR criteria (OSF registration link: https://osf.io/jr7xe/). A literature search was run to identify studies investigating soccer-related injury risk factors. We included systematic reviews published between 2013 and 2023 related to soccer and analysed the identified risk factors to classify these in intrinsic and extrinsic, group in categories and identify relationships between risk factors and injury location. Among 240 risk factors, 181 (75.4%) were classified as intrinsic and 59 (24.6%) as extrinsic. We grouped risk factors in 14 categories. Finally, we found relationships between risk factors and injury locations for 159 factors, with the knee representing the body area most affected by risk factors (N = 101), followed by the ankle (N = 65) and the thigh (N = 65).

Futsal playing surface characteristics significantly affect perceived traction and change of direction performance among experienced futsal players

We aimed to clarify the effect of different futsal playing surface structural properties on the resultant change of direction (COD) performance, perceived traction and frictional properties. Twenty experienced male university soccer players performed a COD slalom-course test and perceived traction evaluation on three different types of playing surfaces (area-elastic: AE, point-elastic no.1: PE1 and point-elastic no.2: PE2). Frictional properties of these surfaces were mechanically evaluated against a futsal shoe, using a hydraulic moving force platform, and expressed as available friction coefficient (AFC). In the COD performance test, the participants performed significantly better on the point-elastic surfaces (PE1 and PE2) when compared to the area-elastic surface (AE) (p < 0.05). Also, the PE2 surface was found to have the highest perceived traction (p < 0.001). The findings suggest that the relatively higher (4%) AFC explains the improvement in performance and traction perception on the PE2 surface. In this study, we successfully demonstrated that the structural difference (AE or PE) of futsal playing surface has a significant impact on the COD performance of experienced futsal players and their perceived level of traction (PE2) and the frictional properties.

Primary Anterior Cruciate Ligament Injury: Extrinsic and Intrinsic Risk Factors

Anterior cruciate ligament (ACL) injuries continue to increase in incidence despite extensive research into prevention strategies. Many extrinsic and intrinsic risk factors for sustaining ACL injuries have been identified and continue to be investigated. Extrinsic risk factors for ACL injury relate to the athlete's environment, such as the shoe-surface interaction, weather conditions, and sport played. Intrinsic risk factors relate to the athlete's sex, hormones, knee anatomy, landing and pivoting biomechanics, and neuromuscular control. Recent research has highlighted the role of the bony morphology of the proximal tibia and distal femur on primary ACL injury risk, as well as the risk for ACL graft failure. Sex differences in bony and ligamentous morphology of the knee, neuromuscular control, and hormonal factors, such as serum relaxin levels and variations within the menstrual cycle, have been correlated with a higher risk of noncontact primary ACL injuries in female athletes compared with male athletes.

ACL Injury Etiology in Its Context: A Systems Thinking, Group Model Building Approach

Background/Objectives: Given the complex nature of Anterior Cruciate Ligament (ACL) injury, it is important to analyze its etiology with suitable approaches in order to formulate intervention strategies for effective prevention. The present study employs system thinking techniques to develop a Causal Loop Diagram (CLD) Model for investigating the risk factors for ACL Injury (CLD-ACLI), through a Group Model Building approach. Methods: A two-stage procedure was applied involving a comprehensive literature review followed by several systems thinking group-modeling co-creation workshops with stakeholders. Results: Based on input from experts and stakeholders, combined with the latest scientific findings, the derived CLD-ACLI model revealed a series of interesting complex nonlinear interrelationships causal loops between the likelihood of ACL injury and the number of risk factors. Particularly, the interaction among institutional, psychological, neurocognitive, neuromuscular, malalignment factors, and trauma history seem to affect neuromuscular control, which subsequently may alter the biomechanics of landing, predisposing the ACL to injury. Further, according to the proposed CLD-ACLI model, the risk for injury may increase further if specific environmental and anatomical factors affect the shear forces imposed on the ACL. Conclusions: The proposed CLD-ACLI model constitutes a rigorous useful conceptual presentation agreed upon among experts on the dynamic interactions among potential intrinsic and extrinsic risk factors for ACL injury. The presented causal loop model constitutes a vital step for developing a validated quantitative system dynamics simulation model for evaluating ACL injury-prevention strategies prior to implementation.

The Effects of Pointe Shoes on Ballet Dancers' Biomechanics, Muscle Activity, Movement and Symptoms: A Scoping Review

Introduction: Dancing en pointe requires ballet dancers to stand on the tips of their toes while wearing a structured pointe shoe. Understanding the effect of pointe shoes on ballet dancers' biomechanics, function, symptoms and skin health is essential to guide shoe development and ultimately improve dancer performance. Therefore, the purpose of this scoping review was to map the evidence and identify knowledge gaps related to the effect of wearing pointe shoes on professional and recreational ballet dancers. Method: A scoping review was conducted by searching 6 electronic databases and the International Association for Dance Medicine and Science Bibliography. Results: Thirty-five studies were grouped into 5 categories: pointe shoe factors (eg, toe box and shank, pointe shoe status; 9 studies), shoe types (eg, flat shoes vs demi pointe vs pointe; 10 studies), ballet movements (11 studies), symptoms (5 studies), and intrinsic dancer factors (eg, foot type/toe length; 7 studies). Studies were published between 1979 and 2023, with 72% (n = 23) published between 2006 and 2020. Most (86%) of the studies were cross-sectional. Most studies explored biomechanical outcomes and the most common data collection device was force plates (19 studies). Overall, there was an insufficient volume of evidence for specific research aims. Significant gaps in knowledge exist regarding functional and performance-based outcomes, injury outcomes including exploration of factors such as shoe age/usage, and pointe shoe treatment factors. Conclusions: Currently the field of research suffers from threats to ecological validity, with many study methods not reflecting ballet-specific demands or environments. The impact of pointe shoes on ballet dancers is a developing research area, and this scoping review can help guide future research decisions. Studies need to target the knowledge gaps and employ rigorous ecologically valid study designs and ensure that findings inform shoe design and dancer education to minimize injury and maximize comfort and performance.

Insurance cost and injury characteristics of anterior cruciate ligament injuries in sub-elite football: A population analysis involving 3 years of Australian insurance data

OBJECTIVES

To investigate the injury characteristics and insurance cost of anterior cruciate ligament injuries in sub-elite football players in New South Wales, Australia.

DESIGN

Descriptive epidemiological study.

METHODS

Three years of insurance records (2018-2020) was used to describe anterior cruciate ligament injury costs and characteristics. Concomitant injuries and the mechanism of injury were determined by analysing the injury descriptions. Claim characteristics and costs are presented by age group (junior = 7-17 years, senior = 18-34 years, and veteran = 35 + years) and sex. Categorical data (including age-groups and sex) are presented as counts and percentages and analysed using a Chi squared or Fisher's exact test. Cost data are reported as means ± standard deviation with 95 % confidence intervals.

RESULTS

Over the course of three football seasons (2018-2020), 786 anterior cruciate ligament injuries were reported to the injury insurance company. The total insurance cost was AU$3,614,742 with direct injury insurance costs accounting for 36.3 % of the total costs. The mean indirect insurance costs were six-fold higher than direct insurance costs (AU$11,458 vs AU$1914). Isolated injuries had an average cost of $4466 whilst concomitant injuries had an average cost of $4951. Surgical costs are excluded from direct cost calculations. The peak injury count occurred in the first month of all three football seasons, immediately after the pre-season.

CONCLUSIONS

Anterior cruciate ligament injuries represent a substantial economic burden to the insurer and individual. The cost data provided can be used for future economic and modelling studies.

Key Thresholds and Relative Contributions of Knee Geometry, Anteroposterior Laxity, and Body Weight as Risk Factors for Noncontact ACL Injury

Background

Limited data exist regarding the association of tibiofemoral bony and soft tissue geometry and knee laxity with risk of first-time noncontact anterior cruciate ligament (ACL) rupture.

Purpose

To determine associations of tibiofemoral geometry and anteroposterior (AP) knee laxity with risk of first-time noncontact ACL injury in high school and collegiate athletes.

Study Design

Cohort study; Level of evidence, 2.

Methods

Over a 4-year period, noncontact ACL injury events were identified as they occurred in 86 high school and collegiate athletes (59 female, 27 male). Sex- and age-matched control participants were selected from the same team. AP laxity of the uninjured knee was measured using a KT-2000 arthrometer. Magnetic resonance imaging was taken on ipsilateral and contralateral knees, and articular geometries were measured. Sex-specific general additive models were implemented to investigate associations between injury risk and 6 features: ACL volume, meniscus-bone wedge angle in the lateral compartment of the tibia, articular cartilage slope at the middle region of the lateral compartment of the tibia, femoral notch width at the anterior outlet, body weight, and AP displacement of the tibia relative to the femur. Importance scores (in percentages) were calculated to rank the relative contribution of each variable.

Results

In the female cohort, the 2 features with the highest importance scores were tibial cartilage slope (8.6%) and notch width (8.1%). In the male cohort, the 2 top-ranked features were AP laxity (5.6%) and tibial cartilage slope (4.8%). In female patients, injury risk increased by 25.5% with lateral middle cartilage slope becoming more posteroinferior from -6.2° to -2.0° and by 17.5% with lateral meniscus-bone wedge angle increasing from 27.3° to 28.2°. In males, an increase in AP displacement from 12.5 to 14.4 mm in response to a 133-N anterior-directed load was associated with a 16.7% increase in risk.

Conclusion

Of the 6 variables studied, there was no single dominant geometric or laxity risk factor for ACL injury in either the female or male cohort. In males, AP laxity >13 to 14 mm was associated with sharply increased risk of noncontact ACL injury. In females, lateral meniscus-bone wedge angle >28° was associated with a sharply decreased risk of noncontact ACL injury.

Ten questions in sports engineering: technology in elite women’s football

The use of technology in football is increasing, although, products predominantly focus on men’s football in performance, safety, comfort, and fit considerations. A recent scoping review identified just 32 published scientific articles on technology in women’s football, despite demands of those playing/working in the women’s game increasing. We wish to highlight the progressions made so far and barriers remaining in the elite women’s football technology to shed a light on this topic and prod researchers and manufacturers to help support the evolution of women’s-football-focussed technological considerations. The ten questions presented in this paper address the generic question on whether women’s specific tailoring is needed (Question 1) as well as addressing specific questions on football technology and engineering, such as the progressions made and ongoing issues in the following areas: football kits, religious considerations (hijab designs), sports bras, football boots, balls, football pitches, performance tracking devices, menstrual cycle tracking devices (Question 2–10). It is evidence that certain areas have received more attention than others and with these ten questions we hope to steer readers towards research and engineering gaps for future work.

Influence of playing surface on match injury risk in men's professional rugby union in England (2013-2019)

The use of artificial playing surfaces in professional rugby union is growing, but their effect on the injury risk profile remains unclear. The aim of this study was to examine the effect of playing surface on match injury risk in men's professional rugby in England. Six seasons of injury data (2013/14-2018/19) were collected from 15 professional English, men's rugby teams participating in domestic and European competition. The incidence, severity, and burden of match injuries were compared across playing surfaces. The dataset included 3351 injuries from a combined European and domestic data set (separated in to 2 categories; artificial and natural/hybrid surfaces) and 2675 injuries from a domestic only dataset (separated into 3 categories; artificial, hybrid, and natural surfaces). There were no differences in incidence rates between surface types on combined European and domestic match data, but injury burden was significantly greater on artificial (3082 days/1000 h, 95% CI 2847-3337) in comparison with natural/hybrid surfaces (2364 days/1000 h, 95% CI 2277-2454, p < 0.001). These differences were primarily driven by a significantly greater mean severity of hip/groin, and foot/toe injuries on artificial surfaces. This is the largest study to date to examine the relationship between surface type and injury risk in rugby union. The average severity and burden of injuries sustained on artificial surfaces was significantly greater compared with those sustained on hybrid/natural grass surfaces. This study can inform those involved in selection of surface for elite sport, weighing up the positive and negative elements of the varying surface types.

Characteristics of Complex Systems in Sports Injury Rehabilitation: Examples and Implications for Practice

Complex systems are open systems consisting of many components that can interact among themselves and the environment. New forms of behaviours and patterns often emerge as a result. There is a growing recognition that most sporting environments are complex adaptive systems. This acknowledgement extends to sports injury and is reflected in the individual responses of athletes to both injury and rehabilitation protocols. Consequently, practitioners involved in return to sport decision making (RTS) are encouraged to view return to sport decisions through the complex systems lens to improve decision-making in rehabilitation. It is important to clarify the characteristics of this theoretical framework and provide concrete examples to which practitioners can easily relate. This review builds on previous literature by providing an overview of the hallmark features of complex systems and their relevance to RTS research and daily practice. An example of how characteristics of complex systems are exhibited is provided through a case of anterior cruciate ligament injury rehabilitation. Alternative forms of scientific inquiry, such as the use of computational and simulation-based techniques, are also discussed-to move the complex systems approach from the theoretical to the practical level.

Playing surface traction influences movement strategies during a sidestep cutting task in futsal: implications for ankle performance and sprain injury risk

This descriptive laboratory crossover trial study examined the intervention of high friction synthetic vs lower friction natural sport surfaces on the ankle joint biomechanics in a sidestep cutting task. Twenty-nine male futsal players performed 5 trials of sidestep cutting task in a laboratory, recorded by an 18-camera motion capture system to obtain the ankle joint orientation, velocity and moment. Utilised friction was obtained by the peak ratio of the horizontal to vertical ground reaction force during the stance. Repeated measures (MANOVA) suggested a significant effect of the playing surface and post hoc paired t-tests revealed significantly higher utilised coefficient of friction, higher peak plantarflexion angle, lower peak eversion angle, higher peak inversion velocity, lower peak inversion moment and higher peak internal rotation moment. In performing a sidestep cutting task, futsal players demonstrated higher utilised ground friction when available friction from the playing surface was higher, resulting in higher peak inversion velocity and higher peak internal rotation moment, which may make the ankle joint more prone to sprain injury. Floorings for futsal should have an adequate coefficient of friction for agility and avoidance of the risk of slipping. Increasing the coefficient of friction may not only enhance performance but also endanger the ankle joint.

Synthetic playing surfaces increase the incidence of match injuries in an elite Rugby Union team

OBJECTIVES

To examine differences in match injury incidence between three playing surfaces in elite Rugby Union.

DESIGN

Prospective cohort.

METHODS

Match injury incidence was assessed in 89 elite Rugby Union players over two-seasons of professional competition (44 matches, 1014 h player exposure). Match injury incidence was assessed on three different playing surfaces; natural grass, hybrid (natural grass combined with approximately 3% synthetic fibres) and fully synthetic (sand and rubber infill). Overall injury incidence, contact and non-contact injury incidence, and the incidence of minor (≤7 d lost) and major (≥8 d lost) injuries were considered using mixed effect models.

RESULTS

Overall match injury incidence doubled on hybrid and synthetic surfaces compared to natural grass (hybrid: OR = 2.58 [95% CI 1.65-4.03], p < 0.001; synthetic: OR = 2.16 [95% CI 1.07-4.37], p = 0.033). Furthermore, the odds of sustaining a contact injury on a pitch containing any synthetic content also increased compared to natural grass (hybrid: OR = 2.31 [95% CI 1.41-3.78], p = 0.001; synthetic: OR = 2.19 [95% CI 1.00-4.77], p = 0.049). The hybrid surface elicited a four times greater likelihood of non-contact injury incidence compared to natural grass (OR = 4.18 [95% CI 1.16-15.04], p = 0.028). However, the playing surface did not affect the severity of match injuries (all p > 0.05).

CONCLUSIONS

The present study suggests that even a small percentage (3%) of synthetic content in the playing surface significantly increases match injury incidence, with an effect seen on both contact and non-contact injury incidence. These findings are important to enable practitioners to be aware of the injury implications of playing matches on hybrid and synthetic pitches.

Movement Technique During Jump-Landing Differs Between Sex Among Athletic Playing Surfaces

Pryor, JL, Burbulys, ER, Root, HJ, and Pryor, RR. Movement technique during jump-landing differs between sex among athletic playing surfaces. J Strength Cond Res XX(X): 000-000, 2020-Whether athletic surface type affects movement technique, a causal factor for lower extremity injury, is unclear. This study evaluated the influence of 4 common athletic surfaces on movement technique using the Landing Error Scoring System (LESS). Secondarily, we aimed to evaluate differences in movement technique between men and women among surfaces. Recreationally active men and women (n = 38) completed jump-landing tests on 4 common athletic surfaces in a quasi-randomized crossover fashion. Vertical jump height, perceptual fatigue, and muscle soreness were evaluated before jump-landing movement analyses and were similar across testing sessions (p > 0.05). Men achieved higher LESS scores on hardwood and artificial pellet turf compared with women (p ≤ 0.037). Women exhibited lower LESS scores on grass and artificial turf vs. concrete (p ≤ 0.048). Data indicate differential lower extremity movement technique and therefore injury risk across athletic surface types and sex, challenging the generalizability of the LESS construct. Athletic playing surface should be considered during movement technique assessment and implementation of injury prevention programs.

Six different football shoes, one playing surface and the weather; Assessing variation in shoe-surface traction over one season of elite football

INTRODUCTION

An optimal range of shoe-surface traction (grip) exists to improve performance and minimise injury risk. Little information exists regarding the magnitude of traction forces at shoe-surface interface across a full season of elite football (soccer) using common football shoes.

OBJECTIVE

To assess variation in shoe-surface traction of six different football shoe models throughout a full playing season in Qatar encompassing climatic and grass species variations.

METHODS

Football shoes were loaded onto a portable shoe-surface traction testing machine at five individual testing time points to collect traction data (rotational and translational) on a soccer playing surface across one season. Surface mechanical properties (surface hardness, soil moisture) and climate data (temperature and humidity) were collected at each testing time point.

RESULTS

Peak rotational traction was significantly different across shoe models (F = 218, df = 5, p <0.0001), shoe outsole groups (F = 316.2, df = 2, p < .0001), and grass species (F = 202.8, df = 4, p < 0.0001). No main effect for shoe model was found for translational traction (F = 2.392, p = 0.07).

CONCLUSIONS

The rotational (but not translational) traction varied substantially across different shoe types, outsole groups, and grass species. Highest rotational traction values were seen with soft ground outsole (screw-in metal studs) shoes tested on warm season grass. This objective data allows more informed footwear choices for football played in warm/hot climates on sand-based elite football playing surfaces. Further research is required to confirm if these findings extend across other football shoe brands.

Anterior cruciate ligament injury risk factors in football

INTRODUCTION

Anterior cruciate ligament (ACL) lesion represents one of the most dramatic injuries in a football (soccer) player's career. There are many injury risk factors related to intrinsic (non-modifiable) and/or extrinsic (modifiable) factors of ACL injury.

EVIDENCE ACQUISITION

Research of the studies was conducted until September 2018 without publication data limitation or language restriction on the following databases: PubMed/MEDLINE, Scopus, ISI, EXCERPTA.

EVIDENCE SYNTHESIS

To date, evidence from the literature suggests that the risk of ACL injury is multifactorial and involves biomechanical, anatomical, hormonal, and neuromuscular factors. Despite this relative complexity, the mechanisms of injury are well known and rationally classified into two categories: mechanisms of injury based on contact or on non-contact with another player, with the non-contact injury mechanisms clearly prevailing over the mechanisms of contact injury. One of the most frequent biomechanical risk factors, associated with ACL non-contact injury, is represented by the valgus knee in the pivoting and cutting movements and in the landing phase after jumping. Gender-related risk factors show female populations to have a higher predisposition to ACL injury than males However, there are still some theoretical and practical aspects that need further investigation such as; genetic risks together with the role of estrogen and progesterone receptors in female populations, and the in-vivo interaction shoe-playing surface. In particular, the genetic risk factors of ACL lesion seem to be an interesting and promising field of investigation, where considerable progress has still to be made.

CONCLUSIONS

This narrative review provides an insight into the risk factors of ACL injury that could be used by practitioners for preventing injury in football (soccer).

Motivation for sports participation, injury prevention expectations, injury risk perceptions and health problems in youth floorball players

PURPOSE

Describe the motivation for floorball participation, injury prevention expectations, injury risk perceptions and prevalence of health problems in youth floorball players at the start of the season.

METHODS

This cross-sectional survey is part of a larger Sport Without Injury ProgrammE (SWIPE) project and provides baseline data before a cluster randomised controlled trial of an injury prevention program (Knee Control). A baseline survey (online and paper based) was collected from 47 teams with 471 youth floorball players from two provinces of Sweden before the start of the 2017 season.

RESULTS

The mean age for 140 females and 331 males was 13.7 (± 1.5) and 13.3 (± 1.0) years, respectively. The two most significant motivators for floorball participation were being part of the team (82% females, 75% males) and friends (65% females, 70% males). Fractures (84% females, 90% males), eye injuries (90% females, 83% males) and concussion (82% females, 83% males) were perceived as the most severe injuries. 93% of players believed that sports injuries can be prevented, while 74% believed it is unlikely that they will sustain an injury. Existing health problems at the beginning of the season were prevalent in 33% of players, with 65% being injuries and 35% illnesses. 17% of existing injuries at the start of the season caused time-loss from play and 17% required medical attention.

CONCLUSION

Social aspects were the greatest motivators for floorball participation in youths, suggesting that these factors are important to retain sports participants. The high number of health problems in youth is a concern; as such more effort, resources and priority should be given to sports safety programs. Many players believed that sports injuries can be prevented, possibly providing a fertile ground for implementation of such programs.

LEVEL OF EVIDENCE

IV.

The effect of landing surface on landing error scoring system grades

Different landing surfaces may affect lower extremity biomechanical performance during athletic tasks. The magnitude of this effect on clinical screening measures such as jump-landings is unknown. This study determined the effect of court (CS), grass (GS), and tile (TS) surfaces on Landing Error Scoring System (LESS) grades. A repeated-measures design was used. A total of 40 (21F, 19M; mean age = 23.8 ± 2.4 yr) recreational athletes performed a jump-landing task on three different landing surfaces. 2D videography recorded jump-landings in the frontal and sagittal planes. A 2 × 3 (sex by surface) mixed-model repeated-measures analysis of variance was used to examine main and interaction effects associated with surface and sex. No significant sex by landing surface interactions existed for LESS grades. No significant differences were observed on LESS grades for the main effect of surface (CS = 4.83 ± 1.31 points; GS = 5.01 ± 1.40 points; TS = 5.09 ± 1.86 points; all p > 0.05). Correlations were found between LESS grades among different conditions (r range = 0.587-0.611; all p < 0.001). Commonly used jump-landing surfaces for clinical biomechanical evaluations do not affect LESS grades, suggesting generalisability as a screening tool for anterior cruciate ligament injury risk in different sport environments.

Sport-specific biomechanical responses to an ACL injury prevention programme: A randomised controlled trial

Anterior cruciate ligament (ACL) injury prevention programmes have not been as successful at reducing injury rates in women's basketball as in soccer. This randomised controlled trial (ClinicalTrials.gov #NCT02530333) compared biomechanical adaptations in basketball and soccer players during jump-landing activities after an ACL injury prevention programme. Eighty-seven athletes were cluster randomised into intervention (6-week programme) and control groups. Three-dimensional biomechanical analyses of drop vertical jump (DVJ), double- (SAG-DL) and single-leg (SAG-SL) sagittal, and double- (FRONT-DL) and single-leg (FRONT-SL) frontal plane jump landing tasks were tested before and after the intervention. Peak angles, excursions, and joint moments were analysed using two-way MANCOVAs of post-test scores while controlling for pre-test scores. During SAG-SL the basketball intervention group exhibited increased peak knee abduction angles (p = .004) and excursions (p = .003) compared to the basketball control group (p = .01) and soccer intervention group (p = .01). During FRONT-SL, the basketball intervention group exhibited greater knee flexion excursion after training than the control group (p = .01), but not the soccer intervention group (p = .11). Although women's soccer players exhibit greater improvements in knee abduction kinematics than basketball players, these athletes largely exhibit similar biomechanical adaptations to ACL injury prevention programmes.

Effects of turf and cleat footwear on plantar load distributions in adolescent American football players during resisted pushing

Metatarsal and midfoot injuries are common in American football. Footwear design may influence injury rates by altering plantar foot loading patterns in these regions. The purpose of this study was to determine the effect of cleat design on in-shoe plantar foot loading during a football-specific, resisted pushing task. Twenty competitive football players (age 14.7 ± 1.8 years, height 1.72 ± 0.10 m, and mass 71.8 ± 26.9 kg) completed three trials of pushing a weighted sled at maximal effort in a standard shoe (CLEAT) and artificial turf-specific shoe (TURF), with flexible in-shoe force measuring insoles. Repeated measures ANOVAs identified mean differences in maximum force and relative load under all regions of the foot. Results showed higher forces in the CLEAT under the medial (p < 0.001) and lateral (p = 0.004) midfoot, central (p = 0.007) and lateral (p < 0.001) forefoot, and lesser toes (p = 0.01), but lower forces in the hallux (p = 0.02) compared to the TURF shoe. Additionally, relative loading was higher in the CLEAT under the medial (p < 0.001) and lateral (p = 0.002) midfoot and lateral (p < 0.001) forefoot, but lower in the medial forefoot (p = 0.006) and hallux (p < 0.001) compared to the TURF shoe. The two shoes elicited distinct plantar loading profiles and may influence shoe selection decisions during injury prevention or rehabilitation practices.

Risk factors of anterior cruciate ligament injury in football players: a systematic review of the literature

BACKGROUND

The ACL lesion represents one of the most dramatic injuries in a sportsman's career. There are many injury risk factors related to intrinsic, or non-modifiable, and extrinsic, or modifiable, factors. In literature at today current evidence suggests that ACL injury risk is multifactorial and involves biomechanical, anatomical, hormonal and neuromuscular factors.

PURPOSE

To perform a systematic review of the literature concerning the ACL injury risk factors in soccer.

CONCLUSION

The injury risk factors show a low level of evidence, further studies in the field are needed.

STUDY DESIGN

Systematic review.