Introduction
Soccer is the world's most popular sport with over 260 million participants worldwide.1 Lower limb (LL) injuries are common in soccer and the negative impacts of these injuries have been well documented.2–7 Recently, injury prevention strategies for soccer have gained increased research attention, particularly the use of injury prevention exercise programmes (IPEPs). The efficacy of IPEPs in amateur soccer teams has been established in large-scale randomised controlled trials (RCTs).8–10 The Knaekontroll programme reduced the overall rate of anterior cruciate ligament (ACL) injuries by 64% in a RCT including over 4500 amateur female soccer players.8 The FIFA 11+, an IPEP endorsed by the FIFA, significantly reduced injuries in large-scale RCTs of amateur female9 and male players10 as well as collegiate male players.11
Alongside growing support for IPEP efficacy, evidence of significant challenges to implementing these programmes has emerged.12 These challenges span aspects of programme reach, adoption, compliance and maintenance, aligning closely with the implementation challenges identified in other team ball sports13–19 and other health-related fields.20–23 To date, the most commonly reported implementation challenges relate to programme compliance (also termed adherence or fidelity). This refers to the extent to which an IPEP is performed as intended. High compliance to IPEPs has been associated with greater injury reductions.11 ,24–26 For example, a subsequent analysis of the aforementioned Knaekontroll RCT8 illustrated that players with high compliance experienced an 88% lower rate of ACL injury, compared with players with low compliance, who did not differ from controls.24 However, achieving adequate compliance can be challenging.27–29
Enhancing the adoption of IPEPs has also been identified as a major implementation challenge.12 ,30 Despite extensive promotion of the FIFA 11+ by soccer's international governing body since 2009, just 10% of the member soccer associations have actually endorsed the programme.12 Coaches have been identified as important adoption targets for IPEPs in amateur soccer,12 whereas other staff members (eg, physiotherapists and fitness staff) represent key programme deliverers in professional and collegiate soccer settings.31–33 In recent studies, just 20% of female soccer team coaches in Utah34 and 21% of female high school soccer and basketball coaches in Oregon35 reported using an IPEP. Among coaches of public high school soccer and basketball teams in Chicago, only 37% agreed to participate in an IPEP trial.36 Injury prevention knowledge gaps among players, coaches and parents have been identified in both male37 and female38 ,39 amateur soccer communities and also in other team ball sports settings.14 ,15 ,17 In one recent study of youth male soccer players, 79% had not heard of the FIFA 11+.37
Improving IPEP maintenance represents another key challenge in enhancing the impact of IPEPs, but information on programme maintenance is rare. In a systematic review on the reporting of team ball sport IPEP trials, maintenance was the least reported of all implementation aspects.40 A recently published, 3-year follow-up41 to the previously mentioned Knaekontroll RCT,8 investigated the maintenance of the programme by amateur female soccer coaches. Use of the programme by still active coaches, in some form, was very high (82% for intervention group coaches and 68% for control group coaches). However, the majority performed the IPEP less frequently than recommended and around three-quarters had modified the content of the programme.41
Research on IPEP implementation in professional soccer settings remains scarce, but awareness of the impact of implementation on injury prevention success in professional teams is growing.42 ,43 In a study of coaches from elite junior female teams,44 high levels of coach intent to deliver an IPEP were observed following a coach workshop. Despite this, only 53% of coaches actually adopted an IPEP during the following season. A recent study in high-level professional male soccer investigated use of the evidence-based Nordic Hamstring (NH) exercise programme.45 Although 88% of clubs were familiar with the NH programme, it was performed fully in only 11% and partly in just 6% of the total 150 club seasons included in the study.
The above research findings underpin a well-established principle of sports injury prevention: no intervention will achieve its full potential unless it is adopted, correctly implemented and maintained over time.46 It has been emphasised that for sports injury prevention measures to succeed, an in-depth understanding of end-user (eg, coach and other programme deliverers) perceptions and the specific implementation context in which the programme takes place is required.15 ,47 ,48
Identification of the factors which influence IPEP implementation can provide valuable information for the design, delivery and support of these programmes, thereby enhancing their success. The tailoring of programmes to specific target groups is also important, with consideration of age,49 ,50 knowledge and beliefs,38 ,39 programme length13 and climate.13 ,26
This study aimed to identify challenges to implementing IPEPs in the specific context of professional male youth soccer, particularly relating to the established reporting gaps of adoption and maintenance.40 As there is currently no industry-standard IPEP for professional soccer, the most highly promoted IPEP for amateur soccer, the FIFA 11+, was used as a blueprint for analysing IPEPs in this study. The specific aims were to:
Analyse the perceptions of soccer coaches, fitness coaches and physiotherapists towards injury prevention in general, IPEPs and specifically the FIFA 11+.
To seek direct input from staff members regarding the challenges to maintaining IPEPs in their setting.