Effects of the FIFA 11+program on performance,biomechanical measures,and physiological responses:A systematic review

Mojt Asgri,Bhreh Nzri,Mrio Bizzini,Thoms Jitner

a Institute for Sport and Sports Science,TU Dortmund University,Dortmund 44221,Germany

b Faculty of Physical Education and Sports Science,University of Tehran,Kish Island branch,Kish Island 79416,Iran

c Human Performance Lab,Schulthess Clinic Lengghalde,Zürich 8008,Switzerland

Abstract Background:The side effects of the FIFA 11+program on performance have not been generally reviewed.The objective of this study was to synthesize the literature on the effects of the 11+on players’performance.Methods:Five online databases(PubMed,Scopus,ScienceDirect,Springer,and Google Scholar)were searched(from April 2006 to March 2022)using predefined keywords and sub-keywords. The potential references were primarily recorded through Endnote and imported to Covidence.Out of the 123 references screened by 2 blinded researchers through the software, 59 full texts were assessed for eligibility, 33 of which were ultimately included.The quality of the studies and the risk of bias were then assessed.Study ID,title,place,aim,design,start/end dates,population description,study criteria,statistical analysis,and outcomes were extracted.Results:Studies were conducted on male and female players aged 10-32 years old.The quality of the studies was moderate to high,and except for unclear bias for blinding outcome assessment,the risk of bias for all domains was low.Long-term application of the 11+improved most biomechanical measures and physiological responses except for lower extremity stability,ankle evertors time latency,ankle dorsiflexion,and proprioception. Conversely, the 11+ showed acute negative effects on physical performance compared to dynamic warm-ups and non-significant effects on technical abilities.Conclusion:Mid-to-long-term implementation of the 11+improved the majority of biomechanical and a couple of physical measures but showed no effects on technical skills.Precaution must be observed for using the 11+before competitions,as it could acutely decrease physical/technical performance. Given the contradictory nature of the literature, further studies should evaluate the short-to-mid-term effects of the 11+. Further studies are required to address ankle responses to the 11+intervention.

Keywords: Football;Futsal;Injury prevention;Systematic review

1. Introduction

The FIFA Medical Assessment and Research Centre launched the 11+ program (2006) to merge injury risk-reducing exercises into a warm-up protocol aiming to mitigate football-related injuries, particularly in sub-elite and amateur players. The available literature strongly supports that except for lower effects on ankle and groin injuries,1-3the 11+ has successfully reached the aim for which it was introduced.4-8Hence, it is labeled an evidence-based and well-structured warm-up program, receiving much attention from sports scientists.Given the advantages it entails in injury prevention,the researchers have consistently recommended the 11+ to be applied as a part of daily routine training. However, how this program can be delivered into the football world has remained a challenging question.2,9In other words, the persuasion of coaches,trainers,and players to accept and follow the 11+has not been entirely successful up to this point.10Some barriers include but are not limited to complaints about prolonged duration,lack of time at training,lack of player enjoyment and engagement,concerns regarding some of the training(namely,Part 2),and lack of a link to football-related goals.11

Another potential reason for such disinclination would be concerns regarding the effects of the 11+ on performance improvement, biomechanical measures, and physiological responses,which appear to interact strongly with the pre-identified barriers.12-17Heterogeneous studies in various designs,representing different age ranges, genders, playing levels, and often including low numbers of participants and different follow-up periods have investigated the 11+on a variety of performance,biomechanical,and physiological measures(Fig.1).

Regarding performance parameters, for example, Zarei et al.15stated that applying the 11+ over a football season enhances agility, vertical jump, and countermovement jump among amateur U16 players. Conversely, Impellizzeri et al.18failed to find the same results after performing the program for 9 weeks among amateur players aged 21-25 years old.Arede et al.19reported a significant improvement in sprinting among child players after they performed the program for 6 weeks,while Trajković et al.20showed that short-term application of the 11+ may not improve sprinting among child players. It becomes more challenging when we consider that Ayala et al.12recently demonstrated that the 11+ might acutely decrease performance parameters such as sprinting when compared to a dynamic warm-up program.Reis et al.21found that the 11+improves dribbling skill among amateur futsal players,whereas Daneshjoo et al.22observed that the 11+produces no impact on the dribbling skill of youth elite football players.

Regarding biomechanical measures, for instance, Daneshjoo et al.16reported that the 11+ do not significantly improve the concentric quadriceps strength of elite players and that improvements in hamstring muscles appeared only in the dominant leg. In contrast, Ghareeb et al.17showed a significant improvement in the strength peak torque of the quadriceps and hamstrings in both dominant and non-dominant legs among amateur players after performing the 11+program.

Fig.1. Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)flow chart.

This lack of clarity regarding the side effects of the 11+alongside the barriers mentioned above has resulted in low compliance and poor implementation of the program,10,23which has even decreased over time. Although compliance and implementation rate have shown a strong correlation to the success of each injury prevention program and team success,9O’Brien et al.10reported that the 11+was only applied in 12%of the training sessions. Thus, trainers have suggested modifying,rescheduling, or applying the 11+ in conjunction with other exercises to be more challenging, to have variation, progression,and individualization, and to be linked to football-specific demands10,24,25or to be done outside of the training sessions.26

Finally, yet importantly, the follow-up period required for successfully implementing the 11+ has remained challenging and needs to be addressed. Although the terms “immediate”,“short-term”, “mid-term”, and “long-term” have been clearly defined in the field of orthopedics,27they have remained undefined in sports science.Hence,they have been arbitrarily used in the studies, and recommendations on the adequate followup duration for the 11+differ from 1 study to another.

Taken together,whether the 11+increases performance and,if so, for how long it should be implemented are questions that remain to be addressed, especially since they may potentially influence the compliance and implementation rate of the program. Although the injury prevention side of the 11+ has been appropriately reviewed,2,5,28to the authors’ knowledge, no systematic review has generally evaluated the impacts of the 11+on players’ performance. Therefore, this study aimed to scrutinize the available literature on the 11+in order to address the effects of the original 11+program on physical performance and technical abilities, physiological responses, and biomechanical measures among football and futsal players. We assume that a synthesis of the available literature will adequately address concerns regarding the performance side of the program.

2. Methods

2.1. Registration and search protocol

This systematic review was aligned with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA) guidelines.29,30It was preregistered in PROSPERO(CRD42021283100) and carried out using Covidence (extraction 2,Cochrane,Melbourne,Australia),a well-established platform for conducting systematic reviews and meta-analyses.31Two blinded members(MA and BN)of the research group systematically and independently searched the PubMed, Scopus,ScienceDirect, Springer, and Google Scholar databases for the period from April 2006 (year of introduction of the 11+) to March 2022. For instance, the following strategy was used to search PubMed:(“11+”OR“the 11+”,OR“the 11+warm-up”OR “the 11+ programme” OR “FIFA injury prevention programme” OR “FIFA11+”) AND (“football” OR “soccer” OR“futsal”)AND(“performance”OR“biomechanics”OR“skill”,OR “EMG” OR “force” OR “kinetic” OR “kinematic” OR“agility” OR “sprint” OR “jump” OR “dribbling speed” OR“pass” OR“heading”,OR“change of direction”OR“balance”OR “stability” OR “flexibility”, OR “muscle strength”, OR“proprioception”, OR “muscle activity” OR “power” OR“endurance” OR “functional test”). A manual crossover search of the eligible references was further performed(November and December 2021) to ensure a complete census of literature on the 11+.

2.2. Literature search and screening

Five pre-identified keywords (the FIFA11+, 11+ warm-up,the 11+ program, the 11+, and FIFA injury prevention programme)were used in conjunction with the following sub-keywords to discover potentially relevant references: football,soccer, futsal, performance, fitness biomechanics, physical/technical performance, Electromyography (EMG), force,kinetic,kinematic,torque,moment,agility,sprint,jump,dribbling speed, pass, heading, acceleration, change of direction,balance, stability, flexibility, muscle strength, power, endurance,proprioception,and muscle activity.Each researcher provided 5 libraries per Endnote (EndNote X9; ClarivateTM,Boston, MA, USA), where the potential references from each database were imported separately. The libraries were then exported to Covidence for further assessments. The software recognized duplicates and merged them into 1 study using study IDs.Additionally,systematic reviews and meta-analyses and papers without full-text access,such as conference papers,current opinions, and letters to editors, were determined to be irrelevant references and were filtered out based on 2“exclude” votes given by 2 blinded reviewers (MA and BN);the rest were considered for primary assessment.

2.3. Study criteria

Studies were included if they(a)investigated the 11+on all performance and biomechanical parameters as well as on physiological responses regardless of the playing level,gender,age, and population description, (b) had a prospective design involving a test battery for assessing performance,biomechanics, and physiological responses, and (c) were published in English.Twofold studies investigating injury and performance were only included if they prospectively assessed and reported performance,biomechanical,or physiological parameters.The studies were excluded if they assessed any other similar programs, such as the 11, FIFA11+kids, FIFA11+referees, and FIFA11+shoulder injury prevention.

In this study,we arbitrarily defined the follow-up periods as(0 to <1 week=acute/immediate, 1 week to ≤6 weeks=short-term, >6 weeks to ≤10 weeks=mid-term, and>10 weeks=long-term).

2.4. Study selection and data collection

Of the 468 primary potential references recorded in our search, the software found 345 duplicates and integrated them.Further, 2 blinded reviewers (MA and BN) screened the titles and abstracts of the 123 potential references through Covidence and voted them separately.Studies with 2“include”votes were considered for eligibility assessment, and those with 2“exclude” votes were excluded. If a conflict arose, the related study was referred to the lead researcher(TJ)for the final decision. Out of the 123 titles and abstracts screened, 59 full texts were reviewed in detail for eligibility, 33 of which were ultimately included in the systematic review.12-22,26,32-52The main reasons for exclusion during this step were not implementing the 11+ to investigate its effects on the performance measures or implementing other interventions, such as FIFA11+kids. The following data were extracted by adjusting the software template:study ID,title,lead author,the country in which the study was conducted, aim, study design, start/end dates, possible conflict of interest, inclusion/exclusion criteria,methods of recruitment of participants, population description,statistical analysis, and results. They were then exported to a Microsoft Excel 2016 (Microsoft Corp., Redmond, WA, USA)spreadsheet.

2.5. Quality of studies,applicability risk of bias

To assess such measures,we adapted the related template on Covidence based on the guidelines of Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2), a recommended tool for assessing the methodological quality, risk of bias, and applicability of the studies.53Two blinded research group members (MA and BN) reviewed the studies independently and scored them separately. When conflicts occurred, the relevant study was double-checked by the lead researcher(TJ).Overall,the quality of the studies was identified to be moderate to high given that nearly half of them(15 studies)had randomized controlled-trial designs15,18,26,32-42,50and the rest had either prospective cohort or non-randomized experimental designs.12-14,16,17,19-22,43-49,51However, most of the studies revealed a lack of ability to recruit enough samples.Indeed,this is not the case for clinical trials but should be considered in further field-based studies. Reviewers’ judgments regarding the risk of bias revealed that except for an indefinite amount of bias for allocation concealment and blinding outcome assessment,the risk of bias for all domains was low.

3. Results

Table 1 presents a comprehensive and detailed summary of the included studies. The experiments were carried out in 15 countries and 4 continents,recruiting female and male players ranging from 10 to 32 years. These statistics reaffirm that the 11+ has been investigated worldwide. Better adherence to the program was associated with a higher impact on performance.42The vast majority of studies (22 studies) evaluated adult amateur players,12-15,17,18,21,26,32-36,38,39,41,43-45,47-49but no study was conducted in professional football. Eleven studies were conducted with youth players, 8 of which included children,13,19,20,40,42,46,50,52and the rest16,22,37evaluated adolescent/youth elite players. Twenty-five studies were conducted with male players;13,15-22,26,33-41,43-48one had a mixed sample,12and 7 studies were conducted with female players,14,32,40,42,49,50,52indicating that female players have not been adequately studied with respect to the 11+. Overall,the 11+ appeared to be more beneficial for performance enhancement when applied in the mid-to-long term. On the other hand,2 studies reported acute negative effects of the 11+on physical and technical abilities.12,48Contradictory results were reported regarding the short-term effects of the 11+ on players’performance.

Table 1(Continued)

Table 1 Summary of 11+studies.

3.1. Effects of the 11+on futsal players

Three studies were undertaken with futsal players,of which one focused on physical performance and technical abilities and found that the 11+significantly increases strength, sprinting,agility,jumping,balance,and slalom dribbling in amateur futsal players.21The other 2 studies conducted by Lopes et al.34,39failed to argue that performing the 11+for 10 weeks improves balance and proprioception and that the improvements do not persist 10 weeks after the intervention.39They also found no significant improvement in knee muscle strength and ankle evertors muscle latency time immediately after the 11+.34However,they revealed that the 11+would significantly enhance eccentric hamstring strength in the long term.34

3.2. Effects of the 11+on football players

Experiments on football players can be classified into studies concentrated on physical/technical performance,functional screening tests, biomechanical measures, and physiological responses to the program.

3.2.1. Effects of the 11+on technical performance and functional screening tests

Only 1 study evaluated the effects of the 11+ on kicking accuracy, and it found a non-significant difference in pre- vs.post-test for this skill.13Two studies assessed dribbling ability following implementation of the program, and they demonstrated that the 11+ has no impact on that skill.15,22Five studies38,39,41,42,47evaluated the effects of the 11+ on functional screening tests, including the functional movement screen(FMS)and the landing error scoring system.The results demonstrated that the 11+ might not improve landing error scoring system and FMS composite scores;40,41,46however,the study of Akbari et al.37showed a significant improvement in landing pattern following an 8-week implementation of the 11+. Meanwhile, 1 study did show positive effects of the 11+on some FMS components.38

3.2.2. Effects of the 11+on physical performance

Three studies indicated that the 11+ might significantly develop sprinting,19,38,45whereas 4 studies failed to find the same results.12,20,22,48A possible improvement of the 9.1 sprint test was also observed by Zarei et al.15Five studies highlighted the superior performance in agility that followed application of the 11+,15,20,22,38,45while 3 studies illustrated that the 11+ did not improve agility.18,40,48Contradictory results were found regarding the impacts of 11+on change of direction measures.19,50Significant enhancement of vertical jump abilities was observed in 6 studies,15,20,22,26,45,50but in contrast, 6 other experiments failed to find the same result in their jump tests.12,18,35,36,40,48Regarding balance ability, 5 studies reported that the 11+ improves balance significantly,13,33,35,42,45while 1 study showed no difference in balance following performance of the 11+.36Another study suggested that the 11+ may not increase balance ability compared to a dynamic warm-up program.17

3.2.3. Physiological responses to the FIFA 11+

Following performance of the 11+ intervention, researchers from 1 study observed an increase in resting oxygen uptake from 325 mL/min ± 87 mL/min to 379 mL/min ± 142 mL/min, an increase in core temperature from 37.3 ˚C±0.3 ˚C to 37.7 ˚C±0.3 ˚C,and an increase in lactate from 1.0 mmol/L±0.2 mmol/L to 2.6 mmol/L±1.1 mmol/L.45Another study addressed changes in muscle activity in terms of increased glucose uptake in the sartorius, semimembranosus, biceps femoris, and hallux muscles,following use of the 11+.47Whittaker et al.32identified structural adaptations of the abdominal wall following performance of the program over a football season. They showed that the 11+ might alter how the abdominal wall is being used.More specifically,the morphological adaptations to the 11+may be related to alterations in neuromuscular control of the trunk. In addition, Impellizzeri et al.18observed better performance in time to stabilization and core stability following application of the 11+. Nakase et al.43revealed that the hip abductor and 11+abdominal rectus could be activated by performing part 2 of the 11+program.

3.2.4. The FIFA 11+and biomechanical measures

There literature consistently implied significant improvements in most biomechanical measures, including peak torque,quadrieceps:hamstring ratios, concentric/eccentric strength of the hamstring muscles in both dominant and non-dominant limbs, concentric strength of the quadriceps, and decrease in knee valgus collapse during a 90˚cut.16,17,22,26,33,34,44,49Additionally,Pardos-Mainer et al.50and Arede et al.19reported that 11+improves inter-limb asymmetries.Conversely,some studies documented a lack of improvement in knee and ankle stability,peak knee abduction moment, balance and proprioception,eccentric quadriceps strength, and ankle evertors latency time.14,26,34,39More details are presented in Table 1.

4. Discussion

This systematic review aimed to address concerns regarding the side effects of the 11+on performance/biomechanical/physiological measures. The findings indicate that mid-to-long term implementation of the 11+with higher adherence may noticeably develop the majority of the biomechanical measures, balance,and core stability but is defective in improving technical skills.However, precaution must be observed while using the 11+before competition,as it may acutely reduce performance parameters such as sprinting and dribbling.Ankle responses to the program were not studied in football players, and limited evidence was available regarding effects on physiological measures such as resting oxygen uptake and core temperature.

Based on the parameter age,the 11+literature can be divided into 3 main categories. The first category includes studies conducted on children players(U14),2 of which indicated that the program produces no impact on the landing error scoring system and FMS scores, Y balance test, and T test.40,46One study reported that the 11+ improves agility,flexibility,and standing long jump but has no impact on sprinting and maximal oxygen uptake (VO2max).19Conversely, 1 study showed a significant improvement in sprinting and change of direction.20That the 11+ improves functional and dynamic balance was also documented by Steffen et al.42and Dunsky et al.;13the latter also found no improvement in kicking accuracy following the 11+.Additionally,Thompson et al.showed that the 11+might reduce some biomechanical risk factors associated with ACL injuries among children female players.

The second category involves studies evaluating adolescent/youth players aged 14-20 years.Four studies observed a significant improvement in hamstring strength following the program.26,17,16,33Two studies reported the usefulness of the 11+ for reducing biomechanical risk factors associated with noncontact ACL injuries.37,49However, Veith et al.26demonstrated no development in knee and ankle stability during single-leg landing following the program. Additionally,Arundale et al.14suggested that the 11+ may require some modifications to impact landing biomechanics and potentially risky movement patterns. Contradictory results were found regarding performance parameters such as agility, vertical jump,balance,dribbling,and sprinting.15,21,22,33,36,38,39

The last category consists of 10 studies evaluating adult(>20 years old) players. Takata et al.47and Nakase et al.43studied physiological responses and concluded that the 11+increases glucose uptake as well as fluorodeoxyglucose in the abdominal, core area, and thigh muscles. One study highlighted that the 11+may not improve the quality of functional movements.41Studies by Brito et al.,44Impellizzeri et al.,18and Lopes et al.34indicated that the 11+ significantly improves time to stabilization,knee muscle strength,and core stability, while the latter also showed that the program does not improve muscle latency time immediately.34That the 11+may not improve vertical jump, sprinting, and agility was documented by Impellizzeri et al.18and Cloak et al.48Further,Ayala et al.12reported that the 11+may acutely reduce sprinting ability,which is in contrast to the results of Bizzini et al.45Taken together, it appears that the 11+ improves the majority of biomechanical measures among youth and adult players.However,it may not improve performance parameters such as vertical jump,sprint,and agility in adults,while a lack of clarity exists regarding such parameters in youth players.

Although the current literature may confirm the capacity for the 11+ to develop the biomechanical characteristics of youth and adult players, there are important questions that should be addressed in future studies.The 11+ has shown non-significant effects on the latency time of ankle evertors, proprioception improvement, and ankle stability in futsal players, particularly in the short term.34,39This may offer a reasonable explanation for the lower effects of the program with regard to preventing ankle injuries. The dynamic stability of the ankle is primarily dependent on muscular activity. Additionally, most ankle injuries (e.g., ankle sprains) occur in an inverted position where there is poor stability,making the joint prone to injury.54Therefore,delay in activation of ankle evertors,which draw back the joint to the proper alignment,reduces joint stability and exposes the athlete to a high risk of injury.55In the 11+ program,there are more static than dynamic exercises, particularly in part 2,and such a static structure could not stimulate the feedback and control mechanisms of the postural system.56In contrast,dynamic exercises may adequately optimize the neuromuscular system and improve proprioception,muscular activity,and joint stability.57However,the effects of the 11+on the biomechanics of the ankle were only studied twice and those studies were exclusively conducted on futsal players. Thus, further clinical trials are highly recommended to clarify the effects of the 11+on the biomechanics of the ankle among football players. Not only for the 11+ but also in general, the association of injury prevention programs, biomechanical risk factors, and footballspecific performance has rarely been studied and remains unknown.10,58Filling in this gap by bridging injury-oriented and performance-oriented studies may help integrate injury prevention programs into daily routine training.

Only 4 studies12,43,45,48evaluated the acute effects of the 11+, 2 of which observed non-significant or even negative immediate effects on sprinting and agility compared to dynamic warm-ups.12,48These findings could at least partially explain why coaches and trainers are not interested in investing in this program in its current form and why they try to modify it according to football-specific demands.10Parameters such as agility and sprinting depend on the training features.59Thus, using exercises similar to football movement patterns/tasks may develop these parameters. Negative effects of the 11+ on acute performance reduce its applicability as a warmup protocol for competitions and intensify the poor implementation and low compliance associated with the program.Therefore, the focus of an injury prevention program should not be restricted to injury prevention but should involve performance improvement. Considering that the 11+ should be a proper warm-up, a new framework is needed to incorporate different training components into this program.

Concerns regarding the mid-to long-term effects of the 11+on parameters such as agility, sprinting, vertical jump, and change of direction cannot be addressed through this review due to the lack of clarity in the available literature. Hence, a further meta-analysis should be conducted to eliminate such bias. Although a few studies evaluated the program’s effects on technical abilities, such as kicking accuracy and dribbling speed, the literature consistently indicates that the 11+ does not improve technical skills among football players.12,13,22However, a significant improvement in slalom dribbling was observed among futsal players following performance of the 11+.21Based on the similarity principle in training, such outcomes appear to be entirely realistic given that no football-specific drill is embedded in the 11+. Meanwhile, increasing the volume of dynamic exercises and adding Copenhagen adduction exercises into the program provides missing eccentric hip adduction strength and may potentially manipulate technical abilities such as kicking accuracy.60The latter, in particular,seems to be a two-fold modification, as it may improve the ability of the 11+ to prevent groin injuries and, more importantly, may help stabilize the lumbar-pelvic-hip complex during kicking and dribbling tasks.

Given the consistency in the current literature regarding the physiological responses to the program, it can be assumed that the 11+ alters how the core and tight muscles are being used32and causes a better core stability.18,43However,to tackle the barriers regarding the use of the 11+,the second part of the program can be applied outside of the training sessions,as that appeared to mitigate severe injuries and improve compliance.25,61

There were a few serious barriers to the way this systematic review was conducted. Most importantly, the follow-up periods were not clearly defined in the 11+studies or in the sports science literature as a whole. Therefore, at some points, the terms “short term”, “mid term”, and “long term” were used with different meanings. Another limitation we encountered was the heterogeneous literature pertaining to the 11+. This systematic review considered all studies conducted on the 11+,which lead to a broad age range(10-32 years old).That broad age range caused some difficulty in terms of deriving a clear discussion, as the effects of any intervention program could differ significantly before, during, and after maturation and in adulthood.

5. Conclusion

Having summarized all the points about the 11+, it can be concluded that mid- to long-term (>6 weeks) application of the program improves the vast majority of biomechanical measures, core stability, and balance abilities. Nevertheless,further studies must evaluate the effects of the 11+on the biomechanics of the ankle.Additionally,a meta-analysis study on the 11+literature should eliminate the available bias regarding the effects of the 11+on performance measures such as agility,sprinting,change of direction,and vertical jump.That the 11+cannot improve technical skills indicates that football-specific exercises should be added to the program. Further, precaution must be observed for when using the 11+ before competition since it may acutely reduce sprinting and agility.

Authors’contributions

MA wrote the first draft of the manuscript,and searched the literature, screened the references, reviewed the articles, and exported the data with BN;they also evaluated the risk of bias and applicability of the studies.MB and TJ revised the original manuscript. All authors have read and approved the final version of the manuscript,and agree with the order of presentation of the authors.

Competing interests

The authors declare that they have no competing interests.

Supplementary materials

Supplementary materials associated with this article can be found in the online version at doi:10.1016/j.jshs.2022.05.001.