Biology of Sport
eISSN: 2083-1862
ISSN: 0860-021X
Biology of Sport
Current Issue Manuscripts accepted About the journal Editorial board Abstracting and indexing Archive Ethical standards and procedures Contact Instructions for authors Journal's Reviewers Special Information
Editorial System
Submit your Manuscript
SCImago Journal & Country Rank
3/2024
vol. 41
 
Share:
Share:
Review paper

Injury incidence and characteristics in adolescent female football players: A systematic review with meta-analysis of prospective studies

Marcos Quintana-Cepedal
1, 2
,
Ismael López-Aguado
1
,
Ana Fernández-Somoano
3, 4
,
Miguel Ángel Rodríguez
1
,
Miguel del Valle
2, 5
,
Hugo Olmedillas
1, 2

  1. Department of Functional Biology, University of Oviedo, Oviedo, Spain
  2. Asturian Research Group in Performance, Readaptation, Training and Health (ASTURES), University of Oviedo, Oviedo, Spain
  3. Unidad de Epidemiología Molecular del Cáncer, Instituto Universitario de Oncología del Principado de AsturiasDepartamento de Medicina, Universidad de Oviedo, Oviedo, Spain
  4. Spanish Consortium for Research on Epidemiology and Public Health (CIBERSP), Madrid, Spain
  5. Department of Cellular Morphology and Biology, University of Oviedo, Oviedo, Spain
Biol Sport. 2024;41(3):137–151
Online publish date: 2024/01/30
Article file
- 14_03450_Article.pdf  [2.72 MB]
Get citation
 
PlumX metrics:
 

INTRODUCTION

Female participation in football is growing in popularity, especially supported by the influence of countries such as France, Sweden, or the United States [13]. Nevertheless, as sports participation grows, the incidence of injury increases [4, 5]. This can compromise future physical function and even lead to damage of the professional career [4, 6, 7] or abandonment of sports practice [8, 9].

Since the publication of the Consensus Statement on injury definition and data collection, interest in injury epidemiology in football has risen [10]. Researchers have focused attention on injuries in adult and young footballers, both professional and amateur [1114]. However, this growth has been significantly biased towards male athletes. Only 21% of the papers included in a recent review reported data on injuries in female adolescent football players [14], high-lighting the underrepresentation of women in research [15]. Another issue in exploring injuries around youth female football is the variability in methodological approaches used between studies.

Differences in injury definition, follow-up time, and study design, among others, are some of the handicaps that prevent researchers drawing strong conclusions regarding this topic [16]. The previous points provide valuable information on what should be the focus when performing a meta-analysis, since the current state-of-the-art only serves to augment uncertainty around decision making.

The existence of anatomical and physiological differences between men and women make imperative the analysis of injuries separately, since this variability influences injury incidence and its characteristics [17, 18]. For example, males sustain more hamstring injuries than female players (0.8 vs. 0.6 injuries per 1000 h of exposure) [19, 20]. On the other hand, females have 2 to 3 times higher risk of sustaining an anterior cruciate ligament (ACL) injury, compared to their male counterparts [21]. Therefore, it seems inappropriate to extrapolate results from one population to another [22]. Regarding age differences, injury incidence in adolescent male football players (5.7/1000 h [14]) is lower than that of male adult players (8.1/1000 h [11]). Main injured locations vary; adolescent injuries affect apophyses and growth plates the most [23], while adult players suffer muscle injuries principally [24].

Previous reviews on young female player injuries have included paediatric participants (inclusion criteria < 19 years of age without a lower threshold), which might confound the results [14]. Also, some criticism has arisen for methodological reasons (i.e. conclusions based on single-point estimates or modification of tools to assess study quality), which implies that results from these investigations must be interpreted with caution [25]. Medical teams prioritize enhancing sports safety by designing and implementing preventive measures, particularly crucial for youth populations. A structured approach, as proposed by van Mechelen, involves three key steps: (1) identifying and describing sport injuries, (2) analysis of risk factors and mechanisms underlying injuries, (3) introduction and effectiveness testing of prevention strategies [26]. We decided to conduct this systematic review with a clear age definition (13 to 19 years of age) and a rigid inclusion criterion due to the variability in injury incidence depending on participants’ age, to address the first step in the “sequence of prevention” [26]. We aimed to summarize the overall information about the incidence, location, type, and severity of injuries in adolescent female football players.

MATERIALS AND METHODS

The study was registered in PROSPERO (code: CRD42020192263), was conducted in accordance with the methods outlined in the Cochrane Handbook, and is reported according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines [27]. The PRISMA checklist is presented in Appendix A.

Study selection

The inclusion criteria for studies to be included in this systematic review were established according with the PICOS question (Population, Indicator, Control, Outcome, and Study design) [27]: (P) include adolescent female football players (i.e., players belonging to federated football teams regardless of category and aged 13–19 years), (I) injury definition in terms of time loss (injury that results in a player being unable to take full part in future football training or match play) [10], (C) interventional studies were included when there was a control group which had not undergone an intervention (control group data were utilized), (O) report either overall, training or match injury incidence rate among the surveyed players, (S) have a prospective design. Additionally, a minimum of 11 players (one team) had to be analysed, and articles were required to be written in English and published in a peer-reviewed journal to be included in the review. “Grey literature” (i.e., conference, abstracts, thesis, and unpublished reports) was not taken into account. Any article failing to meet one of the inclusion criteria was excluded.

Search strategy

All studies were identified through a systematic search on the electronic databases PubMed/MEDLINE, Web of Science, Scopus, SPORT-Discus, Cochrane and PEDro, from inception until October 3rd, 2022. A secondary database search was performed on August 28th 2023, yielding 90 additional records; no additional study was included since inclusion criteria were not met. Reference lists of the included articles were also searched for additional references. Details of the search strategy for PubMed/MEDLINE are shown in Appendix B. Two reviewers (I L-A and HO) independently screened the titles and abstracts of all studies. Duplicate articles were removed using Mendeley Reference Manager. Both reviewers assessed the full text of all potentially eligible articles identified in order to evaluate their possible inclusion in the review. Disagreements over article inclusion were settled through discussion with a third reviewer (MV) until a consensus was reached. The study selection process is presented in Figure 1.

FIG. 1

Flowchart of the study selection for overall, training or match injury incidence.

/f/fulltexts/BS/51824/JBS-41-51824-g001_min.jpg

Data extraction

Data were extracted independently by two reviewers (I L-A and HO) using an electronic data extraction form. The data extracted included the following: (1) General study descriptors (authors, year of publication, place, and study design), (2) characteristics of the subjects (sample size, age and team or place), (3) epidemiological data of injuries (incidence rate and exposure data and distribution by anatomical location). If necessary, the authors of included studies were contacted to provide clarifications or access to raw data. The purpose of the current meta-analysis was to determine the overall effects of: (1) adolescent female football/football-related injury incidence rate (number of injuries×1000 hours of athletic exposure) [28], (2) location of injuries (lower extremity vs. trunk vs. upper extremity vs. head and neck) and (3) affected tissue (muscle vs. ligament).

Risk of bias and study quality assessment

Risk of bias of included studies was assessed by two reviewers (MQ and HO) independently using a modified version of the Newcastle-Ottawa Scale (NOS). The NOS is a quality assessment tool for cohort and case-control studies which contains eight items categorized into three domains (selection of study groups, comparability of groups and ascertainment exposure) and uses a star rating system to indicate the quality of a study. A description of the items used can be found in Appendix C. The higher the number of stars given to an article, the lower is the risk of bias; studies obtaining > 5 stars were classified as having low risk of bias [12].

The methodological quality of the included studies was evaluated using the “Checklist of items that must be included in epidemiological football reports” following the methodology proposed in a recent systematic review [10]. This checklist consists of 19 items of relevant information that any research in this field should contain; we removed two items (age range and gender of players), since these were part of the inclusion criteria and all the articles met both criteria; the description of each item is available in Appendix D. Any disagreement in the assessment of risk of bias or methodological quality was resolved by mutual consent in consultation with a third reviewer (MV).

Quality of the evidence

The quality of evidence (QoE) for the meta-analyses performed was graded using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach [29]. Initially, it was assumed that the quality was high. Quality was downgraded to moderate, low, or very low when one of the following factors was rated as serious, or very serious: risk of bias, inconsistency, indirectness, or imprecision.

Statistical analyses

Data analysis was performed by a statistician (AF). Incidence rates (per 1000 hours of exposure) with the corresponding confidence intervals, and number of participants were extracted from the included studies to a Microsoft Excel (Microsoft Excel, Seattle, USA) sheet by one author (MQ). If data were not specifically reported, we calculated them from the available raw data (number of injuries, no. of games or sessions, exposure hours), using the following formulas:

  1. Incidence = (Ʃ Injuries / Ʃ Exposure) × 1000

  2. Incidence = no. of injuries / (no. of matches × 11 players × match duration*) × 1000

*Match duration, using the factor 1.5, based on standard 90 min match play [12].

Pooled inverse variance-weighted mean injury incidence rate (IR) estimates along with the 95% confidence interval (CI) for the out-comes were calculated using random effects models based on heterogeneity. The usage of random effects models was decided after applying the Cochran Q test (p < 0.10), which measures betweenstudies heterogeneity. Additionally, the variability between studies was estimated with the τ2 statistic. Finally, the statistic I2 was used to measure the percentage of total variation in the effect sizes due to heterogeneity, with > 50% and > 75% representing moderate and high heterogeneity, respectively [30]. Sensitivity sub-analyses were performed to manage heterogeneity. Specifically, a leave-one-out influence analysis was chosen, and the estimation did not change meaningfully, supporting the usage of the random effects model. Forest plots were created to illustrate the effects of the different studies and the global estimation of the meta-analysis. The forest plot for each meta-analysis shows the incidence rates of each study and the pooled incidence rate (overall) for the random effect model, all with their 95% CI and on the logarithmic scale. Statistical analyses were performed using Stata 14.2 (Stata Corporation, College Station, TX, USA) and the mar package (V1.4.6.).

RESULTS

Study selection

The electronic searches retrieved 2768 references from the literature. After duplicates were removed, 1888 records were excluded during title and/or abstract analysis; 70 full-text copies of the remaining studies were obtained and subjected to further evaluation. At the end of the process, 13 publications met the eligibility criteria and were selected for qualitative and quantitative analysis [1, 2, 3141].

Methodological quality assessment

With regards to the risk of bias of the included studies, the mean score obtained on the modified NOS scale was 6 (min: 4, max: 8). Eight studies scored > 5 stars and were considered of low risk of bias [1, 2, 31, 33, 36, 3840] while the rest received lower scores. The main sources of bias were not reporting the proper methodology of exposure collection or estimating these data (item 4), and the lack of specification of whether the participants were healthy at the beginning of the study (item 5). The mean score for the methodological quality assessment was 16.4 out of 19 possible points [10]. Individual study scores for risk of bias and methodological quality can be found in Table 1.

TABLE 1

Characteristics of studies included in the meta-analyses.

ReferenceNº PlayersAgeStudy typeExposure (hours)Nº InjuriesIncidenceRisk of Nº Bias (NOS)Study Quality

OverallTrainingMatchOverallTrainingMatchOverallTrainingMatch
Beech et al. 2022 [31]375U-16Elite club season52,83446,4616,37411152592.11.19.3719

Clausen et al. 2014 [32]43815 to 18Club season27,74621,4616,285269--9.7--518

Hägglund et al. 2009 [33]43317.9 (0.8)Elite international tournament1,7071,2104972391413.57.428.2618

Le Gall et al. 2008 [1]11915 to 19Elite club season97,32587,5309,7956194002196.44.622.4717

Lislevand et al. 2014 [34]93813 to 17Club tournament--1,318--8--6.06515

Schmidt-Olsen et al. 1985 [35]96413 to 19Club tournament--3,913--69--17.6513

Söderman et al. 2001 [2]17515.9 (1.2)Club season11,689--79--6--713

Soligard et al. 2008 [36]83715 (0.7)Club season45,42831,08614,342212741384.732.389.62818

Soligard et al. 2012 [37]235713 to 19Club season--18,376--101--4.62514

Sprouse et al. 2020 [38]585215 to 19Elite international tournament51,15146,1624,9893231901336.314.1126.65716

Steffen et al. 2007 [39]202015.4 (0.8)Club season142,721101,41041,3114561133433.681.118.3618

Steffen et al. 2008 [40]94315.4 (0.8)Club season65,72545,86919,856241--3.66--619

Zebis et al. 2018 [41]18515 to 18Club season--1,559--29--18.6415

[i] NOS = Newcastle-Ottawa Scale, U = Under. Age is presented as mean (SD) when possible or as range or category (i.e., U-16), NOS and Study Quality are measured on a 0–8 and 0–19 scale, NOS bold values indicate low risk of bias studies.

Characteristics of the included studies

Included studies had a prospective cohort design and recorded information on football injuries exclusively. They were published from 1985 [35] to 2022 [31], and the duration of follow-up ranged from 2 days [34] to 8 seasons [1, 38]. The participants’ nationalities were varied; one study was conducted on a Kenyan population [34], one study included participants from international competitions [33], and the rest of the studies were performed in European players [1, 2, 31, 32, 3540]. Regarding level of play, seven studies were performed on elite/sub-elite players [1, 31, 33, 35, 37, 38, 41], while the rest of the studies collected data on amateur populations. Nine studies reported the overall injury incidence [1, 2, 3133, 36, 3840]; six and ten studies reported training [1, 31, 33, 36, 38, 39] and match [1, 31, 3339] injury incidence, respectively. Regarding secondary outcomes, five studies reported the aggregated lower limb injury incidence [2, 31, 32, 36, 40], two studies reported trunk and head/neck injury incidence [1, 31], six studies reported ankle, knee, thigh, and hip/groin injury incidence [1, 2, 31, 32, 36, 40], three studies reported muscle injury incidence [1, 31, 36], and four reported ligament injury incidence [1, 31, 36, 40].

Injury incidence

There were 2,333 injuries in total, of which 838 occurred during training sessions and 1,495 were sustained during games. Random effect models showed an overall injury incidence of 5.2 injuries per 1000 hours of exposure (95% CI: 4.2–6.3, Q = 1449.23, p < 0.001; τ2 = 0.094; I2 = 56%; low QoE), incidence for training injuries was 2.3/1000 h (95% CI: 1.3–4.2, Q = 878.61, p < 0.001; τ2 = 0.48; I2 = 0%; moderate QoE), and match injury incidence was 12.76/1000 h (95% CI: 8.78-18.53, Q = 1288.09, p < 0.001; τ2 = 0.33; I2 = 0%; moderate QoE). Injury match-to-training ratio was 5.8. Overall, training, and match injury incidence is displayed in forest plots and can be observed in Figure 2.

FIG. 2

Forest plot displaying overall (A), training (B), and match (C) injuries with the corresponding 95% confidence intervals.

/f/fulltexts/BS/51824/JBS-41-51824-g002_min.jpg

Injury location

Due to the low number of injuries reported in the studies affecting the upper body, trunk, and head/neck, meta-analyses were performed for lower limb injuries. Injury incidence affecting the lower limbs comprised 3.6 injuries per 1000 hours of exposure (95% CI: 2.1–6.4, Q = 1370.29, p < 0.001; τ2 = 0.4; I2 = 0%; low QoE), secondary analyses for specific body area showed an injury incidence of 0.5 (95% CI: 0.3–0.9, Q = 31.17, p < 0.001; τ2 = 0.27; I2 = 37.2%; low QoE) (hip/groin); 0.7 (95% CI: 0.5–1.1, Q = 72.6, p < 0.001; τ2 = 0.23; I2 = 30.6%; low QoE) (thigh); 0.9 (95% CI: 0.5–1.4, Q = 125.84, p < 0.001; τ2 = 0.28; I2 = 56.2%; very low QoE) (knee); and 1.2 (95% CI: 0.9–1.5, Q = 67.28, p < 0.001; τ2 = 0.07;I2 = 55.9%; very low QoE) (ankle). Forest plots with 95% confidence intervals for the different locations can be found in Appendix E.

Injuries affecting head/neck had the lowest injury incidence. Beech et al. [31] observed 0.1 injuries per 1000 exposure hours (95% CI: 0.1–0.3), while Le Gall et al. [1] reported an injury incidence of 0.03/1000 h (95% CI: 0–0.1). Injury incidence regarding the trunk rated between 0.04 (0–0.1) and 0.1 (0.1–0.3) injuries per 1000 hours of exposure [1, 31].

Three studies reported upper limb injuries, resulting in a higher injury incidence compared to head/neck or trunk injuries. Steffen et al. [40] observed 0.6/1000 h injuries (95% CI: 0.4–0.7), followed by 0.3/1000 h (95% CI: 0.2–0.4) [1], and 0.2/1000 h (95% CI: 0.1–0.4) [31].

Injured tissue

Injuries were specified regarding ligament and muscle tissue. Injuries affecting ligamentous structures had an incidence of 1.3/ 1000 hours of exposure (95% CI: 1–1.6, Q = 54.67, p < 0.001; τ2 = 0.05; I2 = 67.1%; low QoE), while muscle injuries accounted for 0.9 injuries for every 1000 hours of exposure (95% CI: 0.4–1.8, Q = 101.24, p < 0.001; τ2 = 0.36; I2 = 0%; low QoE). Forest plots with 95% confidence intervals for the different injured tissues can be found in Appendix F.

DISCUSSION

This systematic review with meta-analysis aimed to quantify injury incidence rates in adolescent female football players. When aiming to mitigate the risk of suffering injuries, the first step is to define the extent of the problem [26]. Previous systematic reviews with metaanalysis have been performed in adults but recently some criticism has arisen due to methodological reasons [25]. This review focuses on this issue, and analyse the topic from a new perspective; included studies had a prospective design, which increases the reliability of the observed results.

Methodological quality assessment

It is vital to report information in accordance with consensus statements, aiding in the interpretation and analysis of data. We assessed methodological quality with the checklist from Fuller et al. since there is no tool for this purpose in observational studies [10]. In this regard, no threshold was set to determine high-or low-quality studies; it is the authors’ opinion that scores above 15 points (80% of items met) could be categorized as of high quality. Using this threshold, we can be confident that our results are valid, since the mean score of the included papers was 16.4. Additionally, more than half of the included studies were rated as of low risk of bias. Many studies did not report how exposure time was collected; the recording of this value must be accurate since it can affect incidence rates (e.g. when two cohorts have the same number of injuries, the one with lower exposure will have had a higher injury incidence). To properly measure exposure, it is recommended to use weekly forms with individual training and match time.

Injury incidence

The main findings are that adolescent female football players sustain 5.2 injuries every 1000 hours of exposure, the incidence of match injuries (12.76/1000 h) being considerably higher than the incidence observed for training related injuries (2.37/1000 h). These results are in line with those reported by Horan et al. in female adult players, where overall, training and match injury incidence rates of 5.63/1000 h, 3.27/1000 h, and 19.07/1000 h, respectively, were observed [42]. Two hypotheses are proposed as to why injuries occur more often during matches: (1) Training sessions do not mimic match scenarios; it may be possible that players do not perform match-like actions with sufficient intensity during training. Many injuries happen during explosive actions (sprinting, accelerating, changing directions, or jumping) and players may not be well prepared to tolerate the load that these gestures impose on their muscles and joints [43]. In this regard, exposure to near maximal sprinting speed (> 95% of maximal speed) two days previous to a game can prevent hamstring strains; this effect may also be true for different lower limb injuries [44]. (2) Contact between players may be less common during training sessions; contacting situations can result in injuries that cause long absence from the sport [45]. To account for this point, education and promotion of fair play might be the answer to avoid injuries due to a contact mechanism [46].

Injury location

Most injuries affected the lower limbs; we observed an injury incidence rate of 3.65/1000 h in this area. Of these lower body injuries, the ankle was the most affected region (1.22/1000 h), followed by the knee (0.89/1000 h), thigh (0.76/1000 h), and hip/groin (0.50/1000 h). Differences were observed compared to male players, who suffer more injuries to the thigh (1.21/1000 h), followed by the ankle (0.91/1000 h) [14]. This can be explained after analysing injuries regarding affected tissue, where females had more ligamentous injuries while males sustained more muscle injuries. It seems therefore that the most common injury in female football is the ankle sprain. The fact that groin injuries had the lowest incidence (0.5/1000 h) is surprising since males have double the incidence of this condition (1/1000 h); these results need to be interpreted with caution, as injury prevalence is similar between genders when non-time-loss groin problems are also considered [47]. Still, anatomical differences in hip and pelvis morphology exist, which may produce differences in the force distribution around the pelvic ring and predispose males to more injuries [18]. However, no clear conclusions can be drawn to date that can explain these differences [48, 49].

Injured tissue

Our meta-analysis showed an overall time-loss injury incidence rate of 1.30/1000 h and 0.89/1000 h for ligament and muscle tissue, respectively. These results reflect the fact that adolescent players have fewer injuries than adult female elites, who have an injury incidence of 2.7 (muscle) and 2.62 (ligament) injuries per 1000 hours [42]. The difference might due to a constrained calendar in elite football with more games throughout the season and inadequate recovery, favouring the development of lesions [50]. Adolescents face an elevated risk of sustaining ligamentous tears, primarily attributed to the raised concentration of oestrogen during the postmenarchal period, which can affect the integrity of ligament structures, leading to hyperlaxity and increased vulnerability, particularly in the ankle and knee ligaments [51, 52]. Additionally, adolescents undergo a period of significant biological changes, encompassing alterations in muscletendon junctions, ligaments, cartilage, and bone density. These changes may render them more susceptible to injuries due to their reduced capacity to tolerate mechanical loads [53]. Furthermore, during this developmental stage, motor skill performance can be impaired by rapid growth, placing additional stress on tissues beyond their typical limits [54, 55]. Lastly, it must be highlighted that youth players experience heightened exposure to football, characterized by increased session frequency, intensity, duration, diverse game formats, and variations in pitch size. This increased exposure may further augment their susceptibility to injuries [56].

Future directions

In order to reduce the risk of suffering a certain injury, the first step is to know the extent of the problem (incidence, prevalence, burden); this study aids in that direction but more research should focus on specific injuries such as ankle sprains, anterior cruciate ligament (ACL) tears, or hamstring strains. It is the authors’ opinion that studies on this topic should meet the following criteria to be considered of sufficient quality to be reliable: prospective design, sufficient injury collection time (at least 1 season), diagnosis performed by either a physician or a physiotherapist, regular (weekly or bi-weekly) collection of football exposure, and data report within a clear age frame (i.e., 13–18 years old). Additionally, data on injury-inciting events should be collected using the Football Injury Inciting Circumstances Classification System, since this information adds further value in the prevention sequence and helps in proposing interventions focusing on the exact mechanisms that lead to injuries [57]. Another step could be to differentiate between hip and groin injuries; the last Consensus on football epidemiology suggested collecting these injuries separately [58]. The same principle could be applied to thigh injuries; it is advised to record anterior and posterior thigh injuries separately [19]. Only after we know the exact epidemiological data for these injuries will we be able to implement risk mitigation strategies using randomized controlled trials to test the effectiveness of these measures in reducing the risk of injury. It is of utmost importance to focus on youth populations since most injuries might be easier to sustain after a primer injury has happened already. Implementing programmes is challenging since these athletes tend to get bored or dislike doing extra exercises that demand more time and might lead to delayed onset muscle soreness [59]. Studies on the adoption of prevention programmes have observed that adherence is low [60, 61]; 17–31% of football clubs use hamstring prevention programmes despite its proven effectiveness, and the situation is similar for adductor preventative exercises [6063]. In this regard, it is advised to educate stakeholders on the benefits of using prevention interventions since effectiveness directly depends on the adherence to the programme.

Limitations

Several methodological limitations must be acknowledged. Some studies were excluded since the injury reporting or definition was not in accordance with the gold standard proposed by the International Olympic Committee [28], which led to only thirteen studies meeting the eligibility criteria. The same problem arose when collecting certain types of injuries. We originally aimed to incorporate studies with a minimum duration of one season. However, due to the limited number of studies meeting our inclusion criteria, this approach was modified and papers with shorter durations were deemed eligible. This modification may have introduced some bias, as studies ranging from 2 days to 8 seasons were combined in our analysis. The checklist of items that must be included in epidemiological football reports was used, despite not being validated, which could have introduced bias in the quality assessment of the included studies. The quality of the evidence could only attain a moderate level in two of the meta-analyses (training and match injuries), and most results were of low quality due to methodological flaws (low number of studies, heterogeneity, or risk of bias), which downgraded the overall quality of the evidence. Some potentially relevant research may have been overlooked due to the absence of a search in the grey literature. It was not possible to perform quantitative analysis of bone injuries since some articles recorded fractures while others measured other types of bone injuries. Insufficient information on specific injuries could be observed, which inevitably led to reporting aggregated data. Lastly, it was not possible to calculate the injury burden due to the lack of data regarding lay-off days due to injury.

CONCLUSIONS

Adolescent female football players are exposed to a substantial risk of sustaining injuries. The anatomical region injured most commonly is the lower extremity (knee and ankle) and the most common types of injury are ligament and muscle/tendon. Future studies should focus on introducing and evaluating preventative and training measures that target the most common diagnoses and the results of this review, in order to reduce the number and severity of injuries within female adolescent football players.

Conflict of interest

The authors declare no conflict of interest.

REFERENCES

1 

Le Gall F, Carling C, Reilly T. Injuries in young elite female soccer players: an 8-season prospective study. Am J Sports Med. 2008 Feb; 36(2):276–84.

2 

Söderman K, Adolphson J, Lorentzon R, Alfredson H. Injuries in adolescent female players in European football: a prospective study over one outdoor soccer season. Scand J Med Sci Sports. 2001 Oct; 11(5):299–304.

3 

DiStefano LJ, Dann CL, Chang CJ, Putukian M, Pierpoint LA, Currie DW, Knowles SB, Wasserman EB, Dompier TP, Comstock RD, Marshall SW, Kerr ZY. The first decade of web-based sports injury surveillance: descriptive epidemiology of injuries in US high school girls’ soccer (2005–2006 through 2013–2014) and national collegiate athletic association women’s soccer (2004–2005 through 2013–2014). J Athl Train. 2018 Sep; 53(9):880–92.

4 

Rauh MJ, Macera CA, Ji M, Wiksten DL. Subsequent injury patterns in girls’ high school sports. J Athl Train. 2007 Dec; 42(4):486–94.

5 

Yard EE, Schroeder MJ, Fields SK, Collins CL, Comstock RD. The epidemiology of United States high school soccer injuries, 2005–2007. Am J Sports Med. 2008 Oct; 36(10):1930–7.

6 

de Loës M, Dahlstedt LJ, Thomée R. A 7-year study on risks and costs of knee injuries in male and female youth participants in 12 sports. Scand J Med Sci Sports. 2000 Apr; 10(2):90–7.

7 

Emery CA, Meeuwisse WH, Hartmann SE. Evaluation of risk factors for injury in adolescent soccer: implementation and validation of an injury surveillance system. Am J Sports Med. 2005 Dec; 33(12):1882–91.

8 

Garrick JG, Requa RK. Sports and fitness activities: the negative consequences. J Am Acad Orthop Surg. 2003 Dec; 11(6):439–43.

9 

Price RJ, Hawkins RD, Hulse MA, Hodson A. The Football Association medical research programme: an audit of injuries in academy youth football. Br J Sports Med. 2004 Aug; 38(4):466–71.

10 

Fuller CW, Ekstrand J, Junge A, Andersen TE, Bahr R, Dvorak J, Hägglund M, McCrory P, Meeuwisse WH. Consensus statement on injury definitions and data collection procedures in studies of football (soccer) injuries. Br J Sports Med. 2006 Mar; 40(3):193–201.

11 

López-Valenciano A, Ruiz-Pérez I, Garcia-Gómez A, Vera-Garcia FJ, De Ste Croix M, Myer GD, Ayala F. Epidemiology of injuries in professional football: a systematic review and meta-analysis. Br J Sports Med. 2020 Jun; 54(12):711–8.

12 

López-Valenciano A, Raya-González J, Garcia-Gómez JA, Aparicio-Sarmiento A, Sainz de Baranda P, De Ste Croix M, Ayala F. Injury profile in women’s football: A systematic review and meta-analysis. Sports Med. 2021 Mar; 51(3):423–42.

13 

Mayhew L, Johnson MI, Francis P, Lutter C, Alali A, Jones G. Incidence of injury in adult elite women’s football: a systematic review and meta-analysis. BMJ Open Sport Exerc Med. 2021; 7(3):e001094.

14 

Robles-Palazón FJ, López-Valenciano A, De Ste Croix M, Oliver JL, García-Gómez A, Sainz de Baranda P, Ayala F. Epidemiology of injuries in male and female youth football players: A systematic review and meta-analysis. J Sport Health Sci. 2022 Nov; 11(6):681–95.

15 

Anderson N, Robinson DG, Verhagen E, Fagher K, Edouard P, Rojas-Valverde D, Ahmed OH, Jederström M, Usacka L, Benoit-Piau J, Foelix CG, Akinyi Okoth C, Tsiouti N, Moholdt T, Pinheiro L, Hendricks S, Hamilton B, Magnani R, Badenhorst M, Belavy DL. Under-representation of women is alive and well in sport and exercise medicine: what it looks like and what we can do about it. BMJ Open Sport Exerc Med. 2023 Apr; 9(2):e001606.

16 

Mandorino M, J. Figueiredo A, Gjaka M, Tessitore A. Injury incidence and risk factors in youth soccer players:a systematic literature review. Part I: epidemiological analysis. Biol Sport. 2023; 40(1):3–25.

17 

Powell JW, Barber-Foss KD. Sex-related injury patterns among selected high school sports. Am J Sports Med. 2000 Jun; 28(3):385–91.

18 

Schache AG, Woodley SJ, Schilders E, Orchard JW, Crossley KM. Anatomical and morphological characteristics may explain why groin pain is more common in male than female athletes. Br J Sports Med. 2017 Apr; 51(7):554–5.

19 

Mullins K, Mac Colgáin D, Carton P. Incidence and severity of hamstring injuries in female athletes who play field sports: A systematic review with meta-analysis of prospective studies. J Orthop Sports Phys Ther. 2022 Aug 5; 1–31.

20 

Tabben M, Eirale C, Singh G, Al-Kuwari A, Ekstrand J, Chalabi H, Bahr R, Chamari K. Injury and illness epidemiology in professional Asian football: lower general incidence and burden but higher ACL and hamstring injury burden compared with Europe. Br J Sports Med. 2022 Jan; 56(1):18–23.

21 

Lucarno S, Zago M, Buckthorpe M, Grassi A, Tosarelli F, Smith R, Della Villa F. Systematic video analysis of anterior cruciate ligament injuries in professional female soccer players. Am J Sports Med. 2021 Jun; 49(7):1794–802.

22 

Faude O, Junge A, Kindermann W, Dvorak J. Injuries in female soccer players: a prospective study in the German national league. Am J Sports Med. 2005 Nov; 33(11):1694–700.

23 

Materne O, Chamari K, Farooq A, Weir A, Hölmich P, Bahr R, Greig M, McNaughton LR. Injury incidence and burden in a youth elite football academy: a four-season prospective study of 551 players aged from under 9 to under 19 years. Br J Sports Med. 2021 May; 55(9):493–500.

24 

Ekstrand J, Spreco A, Bengtsson H, Bahr R. Injury rates decreased in men’s professional football: an 18-year prospective cohort study of almost 12 000 injuries sustained during 1.8 million hours of play. Br J Sports Med. 2021 Oct; 55(19):1084–91.

25 

Mayhew L, Johnson MI, Jones G. Comment on: “Injury Profile in Women’s Football: A Systematic Review and Meta-analysis.” Sports Med. 2021 Dec 1; 51(12):2665–6.

26 

van Mechelen W, Hlobil H, Kemper HC. Incidence, severity, aetiology and prevention of sports injuries. A review of concepts. Sports Med. 1992 Aug; 14(2):82–99.

27 

Moher D, Shamseer L, Clarke M, Ghersi D, Liberati A, Petticrew M, Shekelle P, Stewart LA. Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015 statement. Syst Rev. 2015 Jan 1; 4(1):1.

28 

Bahr R, Clarsen B, Derman W, Dvorak J, Emery CA, Finch CF, Hägglund M, Junge A, Kemp S, Khan KM, Marshall SW, Meeuwisse W, Mountjoy M, Orchard JW, Pluim B, Quarrie KL, Reider B, Schwellnus M, Soligard T, Stokes KA, Timpka T, Verhagen E, Bindra A, Budgett R, Engebretsen L, Erdener U, Chamari K. International Olympic Committee consensus statement: methods for recording and reporting of epidemiological data on injury and illness in sport 2020 (including STROBE Extension for Sport Injury and Illness Surveillance (STROBE-SIIS)). Br J Sports Med. 2020; 54(7):372–89.

29 

Andrews J, Guyatt G, Oxman AD, Alderson P, Dahm P, Falck-Ytter Y, Nasser M, Meerpohl J, Post PN, Kunz R, Brozek J, Vist G, Rind D, Akl EA, Schünemann HJ. GRADE guidelines: 14. Going from evidence to recommendations: the significance and presentation of recommendations. J Clin Epidemiol. 2013 Jul; 66(7):719–25.

30 

Higgins JPT, Thompson SG, Deeks JJ, Altman DG. Measuring inconsistency in meta-analyses. BMJ. 2003 Sep 6; 327(7414):557–60.

31 

Beech J, Jones B, King R, Bennett P, Young S, Williams S, Stokes K, Emmonds S. The incidence and burden of injuries in elite English youth female soccer players. Sci Med Footb. 2022 Dec 1; 6(5):605–15.

32 

Clausen MB, Zebis MK, Møller M, Krustrup P, Hölmich P, Wedderkopp N, Andersen LL, Christensen KB, Thorborg K. High injury incidence in adolescent female soccer. Am J Sports Med. 2014 Oct; 42(10):2487–94.

33 

Hägglund M, Waldén M, Ekstrand J. UEFA injury study--an injury audit of European Championships 2006 to 2008. Br J Sports Med. 2009 Jul; 43(7):483–9.

34 

Lislevand M, Andersen TE, Junge A, Dvorak J, Steffen K. Injury surveillance during a 2-day national female youth football tournament in Kenya. Br J Sports Med. 2014 Jun; 48(11):924–8.

35 

Schmidt-Olsen S, Bünemann LK, Lade V, Brassøe JO. Soccer injuries of youth. Br J Sports Med. 1985 Sep; 19(3):161–4.

36 

Soligard T, Myklebust G, Steffen K, Holme I, Silvers H, Bizzini M, Junge A, Dvorak J, Bahr R, Andersen TE. Comprehensive warm-up programme to prevent injuries in young female footballers: cluster randomised controlled trial. BMJ. 2008 Dec 9; 337:a2469.

37 

Soligard T, Bahr R, Andersen TE. Injury risk on artificial turf and grass in youth tournament football. Scand J Med Sci Sports. 2012 Jun; 22(3):356–61.

38 

Sprouse B, Alty J, Kemp S, Cowie C, Mehta R, Tang A, Morris J, Cooper S, Varley I. The football association injury and illness surveillance study: The incidence, burden and severity of injuries and illness in men’s and women’s international football. Sports Med. 2020 Dec 28; 1–20. doi: 10.1007/s40279-020-01411-8.

39 

Steffen K, Andersen TE, Bahr R. Risk of injury on artificial turf and natural grass in young female football players. Br J Sports Med. 2007 Aug; 41 Suppl 1(Suppl 1):i33–37.

40 

Steffen K, Myklebust G, Olsen OE, Holme I, Bahr R. Preventing injuries in female youth football--a cluster-randomized controlled trial. Scand J Med Sci Sports. 2008 Oct; 18(5):605–14.

41 

Zebis MK, Thorborg K, Andersen LL, Møller M, Christensen KB, Clausen MB, Hölmich P, Wedderkopp N, Andersen TB, Krustrup P. Effects of a lighter, smaller football on acute match injuries in adolescent female football: a pilot cluster-randomized controlled trial. J Sports Med Phys Fitness. 2018 May; 58(5):644–50.

42 

Horan D, Büttner F, Blake C, Hägglund M, Kelly S, Delahunt E. Injury incidence rates in women’s football: a systematic review and meta-analysis of prospective injury surveillance studies. Br J Sports Med. 2022 Oct 13; bjsports-2021-105177.

43 

Aiello F, Di Claudio C, Fanchini M, Impellizzeri FM, McCall A, Sharp C, Brown SJ. Do non-contact injuries occur during high-speed running in elite football? Preliminary results from a novel GPS and video-based method. J Sci Med Sport. 2023 Jul; S1440244023001809.

44 

Buchheit M, Settembre M, Hader K, McHugh D. Exposures to near-to-maximal speed running bouts during different turnarounds in elite football: association with match hamstring injuries. Biol Sport. 2023;40(4):1057–1067

45 

Rekik R, Bahr R, Cruz F, Read P, Whiteley R, D’hooghe P, Tabben M, Chamari K. Mechanisms of ACL injuries in men’s football: A systematic video analysis over six seasons in the Qatari professional league. Biol Sport. 2023; 40(2):575–86.

46 

Bizzini M, Junge A, Dvorak J. Implementation of the FIFA 11+ football warm up program: How to approach and convince the Football associations to invest in prevention. Br J Sports Med. 2013 Aug; 47(12):803–6.

47 

Langhout R, Weir A, Litjes W, Gozeling M, Stubbe JH, Kerkhoffs G, Tak I. Hip and groin injury is the most common non-time-loss injury in female amateur football. Knee Surg Sports Traumatol Arthrosc. 2019 Oct; 27(10):3133–41.

48 

Mosler AB, Weir A, Eirale C, Farooq A, Thorborg K, Whiteley RJ, Hölmich P, Crossley KM. Epidemiology of time loss groin injuries in a men’s professional football league: a 2-year prospective study of 17 clubs and 606 players. Br J Sports Med. 2018 Mar; 52(5):292–7.

49 

Werner J, Hägglund M, Ekstrand J, Waldén M. Hip and groin time-loss injuries decreased slightly but injury burden remained constant in men’s professional football: the 15-year prospective UEFA Elite Club Injury Study. Br J Sports Med. 2019 May; 53(9):539–46.

50 

Altarriba-Bartes A, Peña J, Vicens-Bordas J, Milà-Villaroel R, Calleja-González J. Post-competition recovery strategies in elite male soccer players. Effects on performance: A systematic review and meta-analysis. PLoS One. 2020; 15(10):e0240135.

51 

Parsons JL, Coen SE, Bekker S. Anterior cruciate ligament injury: towards a gendered environmental approach. Br J Sports Med. 2021 Sep; 55(17):984–90.

52 

Wild CY, Steele JR, Munro BJ. Why do girls sustain more anterior cruciate ligament injuries than boys?: A review of the changes in estrogen and musculoskeletal structure and function during puberty. Sports Med. 2012 Sep; 42(9):733–49.

53 

Johnson DM, Williams S, Bradley B, Sayer S, Murray Fisher J, Cumming S. Growing pains: Maturity associated variation in injury risk in academy football. Eur J Sport Sci. 2020 Apr 20; 20(4):544–52.

54 

Lloyd RS, Oliver JL, Faigenbaum AD, Myer GD, De Ste Croix MBA. Chronological age vs. biological maturation: implications for exercise programming in youth. J Strength Cond Res. 2014 May; 28(5):1454–64.

55 

Dupré T, Potthast W. Groin injury risk of pubertal soccer players increases during peak height velocity due to changes in movement techniques. J Sports Sci. 2020 Dec 1; 38(23):2661–9.

56 

Light N, Johnson A, Williams S, Smith N, Hale B, Thorborg K. Injuries in youth football and the relationship to player maturation: An analysis of time-loss injuries during four seasons in an English elite male football academy. Scand J Med Sci Sports. 2021 Jun; 31(6):1324–34.

57 

Aiello F, McCall A, Brown SJ, Serner A, Fortington LV, Huurman SAE, Lewin C, Nagao M, O’Brien J, Panossian A, Pruna R, Ramos GP, Whalan M, Impellizzeri FM. Development of a standardised system to classify injury-inciting circumstances in football: the Football Injury Inciting Circumstances Classification System (FIICCS). Sports Med. 2023 Sep; 53(9):1805–18.

58 

Waldén M, Mountjoy M, McCall A, Serner A, Massey A, Tol JL, Bahr R, D’Hooghe M, Bittencourt N, Della Villa F, Dohi M, Dupont G, Fulcher M, Janse van Rensburg DCC, Lu D, Andersen TE. Football-specific extension of the IOC consensus statement: methods for recording and reporting of epidemiological data on injury and illness in sport 2020. Br J Sports Med. 2023 Jan 6. doi: 10.1136/bjsports-2022-106405. Epub ahead of print.

59 

Lindblom H, Waldén M, Hägglund M. Adherence to injury prevention exercise programmes in amateur adolescent and adult football: A detailed description of programme use from a randomised study. Sports Med – Open. 2023 Jul 15; 9(1):57.

60 

Horst N, Hoef S, Otterloo P, Klein M, Brink M, Backx F. Effective but not adhered to: How can we improve adherence to evidence-based hamstring injury prevention in amateur football? Clin J Sport Med. 2021; 31(1):42–8.

61 

Stensø J, Andersen TE, Harøy J. Adductor Strengthening Programme is successfully adopted but frequently modified in Norwegian male professional football teams: a cross-sectional study. BMJ Open. 2022; 12(9).

62 

Bahr R, Thorborg K, Ekstrand J. Evidence-based hamstring injury prevention is not adopted by the majority of Champions League or Norwegian Premier League football teams: The Nordic Hamstring survey. Br J Sports Med. 2015; 49(22):1466–71.

63 

Ekstrand J, Hallén A, Gauffin H, Bengtsson H. Low adoption in women’s professional football: teams that used the Nordic Hamstring Exercise in the team training had fewer match hamstring injuries. BMJ Open Sport Exerc Med. 2023 May; 9(2):e001523.

Appendices

APPENDIX A. PRISMA CHECKLIST

PRISMA 2020 Checklist

Section and TopicItem #Checklist itemPage where item is reported
Title

Title1Identify the report as a systematic review.1

ABSTRACT

Abstract2See the PRISMA 2020 for Abstracts checklist.Not applicable

INTRODUCTION

Rationale3Describe the rationale for the review in the context of existing knowledge.3

Objectives4Provide an explicit statement of the objective(s) or question(s) the review addresses.4

METHODS

Eligibility criteria5Specify the inclusion and exclusion criteria for the review and how studies were grouped for the syntheses.4–6

Information sources6Specify all databases, registers, websites, organisations, reference lists and other sources searched or consulted to identify studies. Specify the date when each source was last searched or consulted.5

Search strategy7Present the full search strategies for all databases, registers and websites, including any filters and limits used.Appendix 2 (Pubmed)

Selection process8Specify the methods used to decide whether a study met the inclusion criteria of the review, including how many reviewers screened each record and each report retrieved, whether they worked independently, and if applicable, details of automation tools used in the process.5

Data collection process9Specify the methods used to collect data from reports, including how many reviewers collected data from each report, whether they worked independently, any processes for obtaining or confirming data from study investigators, and if applicable, details of automation tools used in the process.7

Data items10aList and define all outcomes for which data were sought. Specify whether all results that were compatible with each outcome domain in each study were sought (e.g. for all measures, time points, analyses), and if not, the methods used to decide which results to collect.7

10bList and define all other variables for which data were sought (e.g. participant and intervention characteristics, funding sources). Describe any assumptions made about any missing or unclear information.7

Study risk of bias assessment11Specify the methods used to assess risk of bias in the included studies, including details of the tool(s) used, how many reviewers assessed each study and whether they worked independently, and if applicable, details of automation tools used in the process.7–8

Effect measures12Specify for each outcome the effect measure(s) (e.g. risk ratio, mean difference) used in the synthesis or presentation of results.8

Synthesis methods13aDescribe the processes used to decide which studies were eligible for each synthesis (e.g. tabulating the study intervention characteristics and comparing against the planned groups for each synthesis (item #5)).8

13bDescribe any methods required to prepare the data for presentation or synthesis, such as handling of missing summary statistics, or data conversions.8

13cDescribe any methods used to tabulate or visually display results of individual studies and syntheses.Not applicable

13dDescribe any methods used to synthesize results and provide a rationale for the choice(s). If meta-analysis was performed, describe the model(s), method(s) to identify the presence and extent of statistical heterogeneity, and software package(s) used.8

13eDescribe any methods used to explore possible causes of heterogeneity among study results (e.g. subgroup analysis, meta-regression).8

13fDescribe any sensitivity analyses conducted to assess robustness of the synthesized results.8

Reporting bias assessment14Describe any methods used to assess risk of bias due to missing results in a synthesis (arising from reporting biases).Not applicable

Certainty assessment15Describe any methods used to assess certainty (or confidence) in the body of evidence for an outcome.Not applicable

PRISMA 2020 Checklist

Section and TopicItem #Checklist itemLocation where item is reported
RESULTS

Study selection16aDescribe the results of the search and selection process, from the number of records identified in the search to the number of studies included in the review, ideally using a flow diagram.6

16bCite studies that might appear to meet the inclusion criteria, but which were excluded, and explain why they were excluded.Figure 1

Study characteristics17Cite each included study and present its characteristics.Table 2

Risk of bias in studies18Present assessments of risk of bias for each included study.9, 11

Results of individual studies19For all outcomes, present, for each study: (a) summary statistics for each group (where appropriate) and (b) an effect estimate and its precision (e.g. confidence/credible interval), ideally using structured tables or plots.12–13

Results of syntheses20aFor each synthesis, briefly summarise the characteristics and risk of bias among contributing studies.

20bPresent results of all statistical syntheses conducted. If meta-analysis was done, present for each the summary estimate and its precision (e.g. confidence/credible interval) and measures of statistical heterogeneity. If comparing groups, describe the direction of the effect.12–13

20cPresent results of all investigations of possible causes of heterogeneity among study results.14

20dPresent results of all sensitivity analyses conducted to assess the robustness of the synthesized results.8

Reporting biases21Present assessments of risk of bias due to missing results (arising from reporting biases) for each synthesis assessed.Not applicable

Certainty of evidence22Present assessments of certainty (or confidence) in the body of evidence for each outcome assessed.Not applicable

DISCUSSION

Discussion23aProvide a general interpretation of the results in the context of other evidence.13–15

23bDiscuss any limitations of the evidence included in the review.16

23cDiscuss any limitations of the review processes used.16

23dDiscuss implications of the results for practice, policy, and future research.15–16

OTHER INFORMATION

Registration and protocol24aProvide registration information for the review, including register name and registration number, or state that the review was not registered. 4 (blinded)

24bIndicate where the review protocol can be accessed, or state that a protocol was not prepared.4

24cDescribe and explain any amendments to information provided at registration or in the protocol.14

Support25Describe sources of financial or non-financial support for the review, and the role of the funders or sponsors in the review.None

Competing interests26Declare any competing interests of review authors.None declared

Availability of data, code and other materials27Report which of the following are publicly available and where they can be found: template data collection forms; data extracted from included studies; data used for all analyses; analytic code; any other materials used in the review.None

[i] From: Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ 2021;372:n71. doi:10.1136/bmj.n71. For more information, visit: http://www.prismastatement.org/

APPENDIX B. SEARCH STRATEGY FOR PUBMED/MEDLINE

PubMed/MEDLINE
#1“Soccer”[Mesh] OR “football”[Mesh]
#2“Soccer”[tiab] OR “football”[tiab] NOT “American football”[tiab] NOT “rugby”[tiab]
#3#1 OR #2
#4“Injuries”[Mesh] OR “Injury” [Mesh]
#5“Injuries”[tiab] OR “Injury” [tiab]
#6#4 OR #5
#7“Prevalence”[Mesh] OR “Incidence”[Mesh]
#8“Prevalence”[tiab] OR “Incidence”[tiab]
#9#7 OR #8
#10“Female”[Mesh] OR “Women”[Mesh]
#11“Female”[tiab] OR “Women”[tiab]
#12#10 OR #11
#13#3 AND #6
#14#9 AND #12
#15#13 AND #14
#16Filters: Adolescent: 13–18 years, Female

APPENDIX C. RISK OF BIAS ASSESSED WITH THE NEWCASTLE-OTAWA SCALE (NOS)

NOS12345678Total
Beech et al. 2022*******7
Clausen et al. 2014*****5
Hägglund et al.2009******6
Le Gall et al. 2008*******7
Lislevand et al. 2014*****5
Schmidt-Olsen et al. 1985*****5
Söderman et al. 2001*******7
Soligard et al. 2008********8
Soligard et al. 2012*****5
Sprouse et al. 2020*******7
Steffen et al. 2007******6
Steffen et al. 2008******6
Zebis et al. 2018****4

Modified Newcastle-Otawa Scale item description (extracted from López-Valenciano et al. 2021).

ItemDescription
1.Description of Sport and participantsThere are several types of football players (sub-elite vs. elite, males vs. females). Without the description regarding to the type of football players it is impossible to conclude which population the incidence rates refer to. Studies that reported a description of the football players or informed the type of football players receive a star for this criterion. Studies conducted in football tournaments (which may determine the type of football players; e.g., World Cup tournaments) and which describe the race characteristics receive a star for this criterion as well. Studies that did not describe the characteristics or the type of football players, and studies conducted in football tournaments that did not describe the characteristics of the tournament did not receive a star for this criterion.

2.Injury definitionStudies that aimed to investigate football-related injuries should present a definition of an injury informing what was considered as an injury in the study. Studies that present a definition of time-loss injury received a star for this criterion.

3.Representativeness of the exposed cohort(a) Truly representative of the average football players in the community*; (b) somewhat representative of the average football players in the community*; (c) selected group of users; (d) no description of the derivation of the cohort.

4.Exposure time collection(a) Secure record*; (b) structured interview*; (c) written self-report; (d) exposure was estimated, (e) no description

5.Demonstration that the outcome of interest was not present at the start of the study(a) Yes*; (b) no. Studies that described that all football players included were injury-free at baseline received a star for this criterion.

6.Assessment of Outcome(a) Independent blind assessment*; (b) record linkage*; (c) self-report; (d) no description.

7.Follow-up time for outcomes to occur(a) Yes*; (b) no. Studies that carried out a follow-up period of at least 12 weeks received a star for this criterion.

8.Adequacy of cohorts follow-up(a) Complete follow-up of all subjects accounted for*; (b) subjects lost to follow-up unlikely to introduce bias (up to 20% loss) or description provided of those lost*; (c) follow-up rate < 80% and no description of those lost; (d) no statement. A loss to follow–up greater than 20% may increase the risk of bias in prospective studies (Fewtrell et al., 2008).

* Articles with this alternative received a star for this criterion.

APPENDIX D. CHECKLIST OF THE METHODOLOGICAL QUALITY ANALYSIS

1234567891011121314151617Ʃ*
Beech et al 202219
Clausen et al 201418
Hägglund et al 200918
Le Gall et al 200817
Lislevand et al 201415
Schmidt-Olsen et al 198513
Söderman et al 200113
Soligard et al 200818
Soligard et al 201214
Sprouse et al 202016
Steffen et al 200718
Steffen et al 200819
Zebis et al 201815

Checklist: Study design (1)Duration (2) Organisational setting (3) Location (4) Nº Teams (5) Nº Players (6) Level of play (7) Medical personnel involved (8) Injury recording frequency (9) Exposure data recording frequency (10) Training to improve quality of data collection (11) Injury definition (12) Exposure definition (13) Nº of match exposures (14) Nº of match injuries (15) Nº of training exposures (16) Nº of training injuries (17).

* All the included studies reported age and gender. Therefore, both items are summed to the final score.

APPENDIX E. FOREST PLOT DISPLAYING AGGREGATED LOWER LIMB (A), HIP/GROIN (B), THIGH (C), KNEE (D), AND ANKLE (E) INJURIES WITH THE CORRESPONDING 95% CONFIDENCE INTERVALS

/f/fulltexts/BS/51824/JBS-41-51824-g003_min.jpg

APPENDIX F. FOREST PLOT DISPLAYING LIGAMENT (A) AND MUSCLE (B) INJURIES WITH THE CORRESPONDING 95% CONFIDENCE INTERVALS

/f/fulltexts/BS/51824/JBS-41-51824-g004_min.jpg
Copyright: Institute of Sport. This is an Open Access article distributed under the terms of the Creative Commons CC BY License (https://creativecommons.org/licenses/by/4.0/). This license enables reusers to distribute, remix, adapt, and build upon the material in any medium or format, so long as attribution is given to the creator. The license allows for commercial use.
 
Quick links
© 2024 Termedia Sp. z o.o.
Developed by Bentus.