The effects of FIFA 11+ exercise program on balance and isokinetic muscle strength on adolescent amateur soccer players

Abstract

Background

This study aimed to examine how muscle strength and balance in adolescent recreational football players were affected by FIFA 11+ (11+). Study design: Randomized controlled study.

Methods

The research comprised 24 football players from a team in an amateur league(age: 16.3 ± 0.8 years; height: 176.9 ± 7.3 cm; body mass: 67.3 ± 8.7 kg; BMI: 21.4 ± 1.9 kg/m²). The experimental group (N = 13) had three applications of the 11 + each week for nine weeks. The usual warm-up was continued by the control group (N = 11). The footballers underwent isokinetic and Star Excursion Balance Tests (SEBT) both before and after an intervention.

Results

Prior to the intervention, the experimental group's right hamstring-to-quadriceps (H/Q) strength ratio at 60 °/sec was significantly higher than that of the control group (p = 0032). Following the intervention, there was no difference between the groups (p > 0,05). After training at 240 °/sec, only the left quadriceps peak torque value of the experimental group was significantly higher compared to the control group (101.2 ± 21.4 vs. 85.8 ± 10.7 Nm, p = 0.042). In the comparisons of the groups after the intervention, the experimental group in SEBT was found to be significantly higher (85.4 ± 9.9 vs. 78.0 ± 6.7 cm, p = 0.040) in the right anteromedial aspect while there were no differences between the groups in the other aspects (p > 0,05). In SEBT, assessments of the within-groups before and after the intervention revealed a significant difference in nearly every aspect between the control group and the experimental group (p < 0,05).

Conclusion

The FIFA 11 + program appears to be more effective in improving dynamic balance than isokinetic muscle strength in adolescent amateur soccer players. These findings suggest that while FIFA 11 + may enhance neuromuscular control, additional strength-focused training may be required to elicit substantial strength gains in this population.

Clinical relevance

FIFA11 + is a widely used programme on adolescent football players, and understanding effects on balance and muscle strength can help to understand efficiency of the programme for injury prevention at early ages.

Keywords

Neuromuscular training injury risk reduction youth sports lower extremity performance athletic conditioning

1 Introduction

Nearly everywhere in the globe today, football is the most popular sportWhile it provides numerous health benefits, its physically demanding nature also increases the risk of injury. This risk is particularly significant during growth and maturation, such as childhood and adolescence, when athletes are developmentally more vulnerable.¹ Injury incidence has recently been correlated with peak height velocity, when rapid development is visible, particularly in adolescent populations.²

Given football's global popularity and high injury rates, the development of evidence-based prevention strategies is essential.³ To address this need, FIFA created the FIFA 11 + injury prevention program, designed primarily for amateur players.⁴ The program comprises three progressive components: (i) running drills and dynamic mobility, (ii) strength, balance, and proprioception exercises emphasizing core and lower-limb control, and (iii) plyometric and agility tasks with a focus on correct landing and change-of-direction technique. Randomized controlled studies have demonstrated the program's effectiveness in reducing injuries among college-aged male athletes⁵

A small selection of exercises focused on sprinting, strength, plyometrics, balance, and stability are provided by the FIFA11 + preventive and warm-up program. The second phase of this workout regimen may be essential for enhancing physical performance and lowering injury rates. For instance, altering the FIFA11second +'s phase at the conclusion of practice would decrease injuries and improve players’ program compliance.⁶ Additionally, FIFA11second +'s section does not have any exercises focused on certain match circumstances or ones that are football-specific or require coordination. Comparing this type of training to FIFA11 +'s usual activities could result in higher physical performance.⁷

Although the FIFA 11 + was conceived primarily as an injury-prevention tool, understanding its effects on physical performance is also critical, as such adaptations may help explain observed reductions in injury incidenc.⁸ Despite the widespread use of FIFA 11+, relatively few randomized trials have examined its impact on athletic performance compared with control groups or alternative interventions.^9–12 Existing studies provide mixed results regarding improvements in dynamic balance and strength.^12–16 Moreover, recent research in female futsal has shown meaningful improvements in jump height and agility following its implementation, highlighting the program's potential beyond injury prevention.¹⁷

In football, athletic performance relies heavily on dynamic balance and muscular strength, which are essential for executing quick directional changes, maintaining postural control during play, and preventing injuries.¹⁸ Isokinetic muscle strength, in particular, is a reliable indicator of neuromuscular function and muscular balance, both of which play a critical role in performance and injury risk.¹⁹

Although the FIFA 11 + program is primarily designed for injury prevention, its effects on performance-related parameters are still not fully understood, particularly in youth populations. Previous studies have largely focused on adult or elite football players, and the findings related to strength and balance outcomes remain inconsistent. In addition, most studies have examined these parameters separately, despite their combined importance for neuromuscular function and injury risk in football.^2,16,20 Evidence regarding the effects of the FIFA 11 + program in adolescent amateur soccer players is limited. This population constitutes a large proportion of football participants and differs from elite samples in terms of training exposure and physical development. Therefore, the purpose of the present study was to investigate the effects of a nine-week FIFA 11 + program on dynamic balance and isokinetic knee muscle strength in adolescent amateur soccer players using a randomized controlled design.

2 Methods

2.1 Procedure

For this inquiry, a single-blinded, prospective randomized controlled trial was designed with a pre-test/post-test longitudinal design. The study aimed to investigate the effects of the FIFA 11 + program on balance and isokinetic muscle strength in adolescent amateur male football players. Data collection was performed at baseline and after an 9-week intervention period. Total of 24 volunteers were separated into experimental (N = 13) and control group (N = 11). Randomly selected groups were split into the experimental and control groups. A blinded assistant randomly assigned the fully qualified players who took part in the study to the control and experimental groups (allocation ratio: 1:1) without the participants’ knowledge or consent. The group distribution was placed inside one of two sealed, opaque envelopes during the randomization process. Both at baseline and nine weeks after baseline, all subjects underwent testing. The group to which participants belonged was unknown to the evaluator. The following testing protocols were applied to the participants: an examination of muscle strength (Isokinetic assessment), dynamic balance (Star Excursion Balance Test). The assessments were conducted under consistent conditions to ensure reliability, and all tests were administered by the same trained physiotherapist.

The individuals of the control group were instructed to carry on with their routine warm-up after the baseline measurements were finished. Stretching exercises and 15 min of jogging make up this routine. The FIFA 11 + training for the experimental group included six different running exercise types, six workouts with three difficulty levels to increase the participants’ core stability, strength, agility, etc., advanced running drills include planting, cutting, and bounding.³ Warm-up time in the control group was the same as in the experimental group (20–25 min). After nine weeks, the evaluations from the first week of the season were repeated.

The intervention period was from April 2019 to June 2019 (the season) (end of the season). The evaluations were conducted at the Sports Club and the Training and Research Hospital's Physical Therapy and Rehabilitation Unit. The study was examined by Ethics Committee of Clinical Research at a meeting on September 26, 2018, under registration number 1522, and it was determined to be ethically acceptable. The CONSORT recommendation used as the study's guide.²¹ The flow pattern is shown in Figure 1.

Figure 1.

Consort diagram showing the flow of the participants through each stage of randomized trail.

2.2 Outcome measures

Players were invited to take part in the study one week prior to the initial evaluation, and we used a questionnaire to collect descriptive data (demographic information and information about prior injuries). The first evaluation of the players was then completed.

The examiner provided each participant with verbal instructions and visual examples for each testing process. Before their training session and after a 48-h recovery period following the previous game, all tests were conducted at the start of the week.

2.2.1 Balance assessment

The Star Excursion Balance Test (SEBT) was used to test dynamic postural control. The testing system's center was used to position the foot such that it could be equally divided in the anterior-posterior and medial-lateral planes. The eight orientations of SEBT are anterior, anteromedial, lateral, posterolateral, posterior, posteromedial, and medial. Players were instructed to extend much further as they could along the predetermined lines, lightly reaching the line with the most distal portion of the extending foot on the ground. They were then instructed to return to the extending leg to a two-leg stance and ensure stability with one leg while the other stayed in the system's center. Depending on whether they were using their left or right leg, players rotated the SEBT test either clockwise or counterclockwise. During testing, participants were instructed to maintain their fixed leg's heel on the floor and their two hands on the pelvis. Players took six practice tests prior to the test to assess any learning effects and serve as a warm-up. Players got a five-minute break following the practice trials to unwind before taking the assessment. Furthermore, they were given that much time between tests as the players needed in order to minimize tiredness. The reach distances were assessed from the system's beginning point on the band line and recorded with a marker at the point of greatest reach. The average cm was saved in each direction after three repetitions of the test.¹² Hertel et al. created the most used method for the SEBT (. The intraclass correlation coefficients (ICC) found by Plisky et al. and Hertel et al. were high and ranged from 0.78 to 0.96. Interrater reliability for the SEBT was found to be strong to outstanding for both normalized and raw scores, according to Hyong et al.²²

2.2.2 Isokinetic assessment

Isokinetic muscle strength measurements were performed using the Cybex Norm dynamometer (Cybex, a division of Lumex, Inc., Ronkonkoma, New York, USA), a widely validated device for assessing muscle performance. The equipment allows for precise, controlled measurement of concentric and eccentric muscle contractions at various angular velocities, providing reliable and reproducible data on muscle strength and balance.After performing dynamic stretches for the flexor and extensor muscles, a normal warm-up regimen, of 10 min was used on an ergometric bike prior to all measurements. To execute the best testing, each player first took a seat and positioned themselves in their most comfortable positions. The player was then fastened with bells over the shoulder, chest, and hip. The isokinetic dynamometer linked the proximal malleoli of the ankle to the cuff of the pry arm. The dynamometer was positioned at 90 degrees and inclined at 0 degrees, while the seat was slanted between 70 and 85 degrees and the seatback was at 90 degrees. The lateral epicondyle of the knee was used to collimate the dynamometer's rotating axis. The manufacturer's recommendations for player position and device setup, which were also consistent with earlier research, were followed. Each player's testing and seating arrangements were documented and replicated during the post-test. Starting repetitions were always performed prior to each test speed for evaluation. Extensor and flexor muscles’ concentric effort was tested. Players then performed concentric knee extension and flexion 15 times at 240 ◦ /sec and five times each at 60 ◦ /sec. Furthermore, they had a one-minute rest between each angular velocity, then a three-minute break after the system setting for the opposing leg was modified. For both the non-dominant and dominant legs, the testing row was randomly chosen. Verbal coaching and visual feedback were used to motivate all players. Final testing period Peak torque (PT) measurements in newton-meters (Nm) for the quadriceps and hamstrings, as well as the ratio of peak torque to body weight (PT / BW) measurements in newton-meters per kilogram (Nm/kg), and the H / Q ratio percent, were taken.^23,24 Peak torque values were normalized to body mass and expressed as $Nm \cdot {kg}^{- 1} \times 100$ , consistent with previous isokinetic studies.

2.3 Intervention

11 + program; It consists of time-consuming, sport-specific activities that are easy to learn, quick to recall, and uncomplicated. The F 11 + was divided into three sections: part 1 included running exercises; part 2 of the workout included six exercises with three challenging levels to improve core stability, balance, and muscular control. Advanced running drills were covered in the third and final part.²⁵ During the warm-up, the coach and two intervention players were chosen to administer the FIFA 11+, with formal training being ensured by the researcher. The researcher did an oral and practical presentation to aid in the learning process for the F 11 + software, and before the exercise, participants were given a copy of the text and a video showing the program in action. Prior to data collection, all participants completed a standardized warm-up and familiarization procedure consisting of submaximal and maximal practice trials to ensure consistent maximal effort during testing. Peak torque was derived from a single standardized set at each angular velocity to minimize fatigue and testing burden in this adolescent amateur population.The standard training regimen was usually conducted three times each week for nine weeks, lasting 20- 25 min in total. The training group received three weekly applications for the F 11 + training program. The usual exercise program was continued by the control group. On predetermined data-collecting forms, the player's presence and the frequency of sessions were recorded.

2.4 Statistical analysis

The statistical analysis was conducted using SPSS 18.0 software. Descriptive statistics are presented as numbers and percentages for categorical variables, and as mean ± standard deviation for numerical variables. Because multiple secondary outcomes were analysed, no formal multiplicity adjustment was applied; findings are interpreted as exploratory, and standardized effect sizes with 95% confidence intervals are reported alongside p-values (α=0.05, two-sided).Categorical variables were compared using the Chi-square test. Given the small group sizes and numerous endpoints, non-parametric tests (Mann–Whitney U / Wilcoxon signed-rank) were used as robust alternatives that do not assume normality.The Wilcoxon Signed-Rank Test was used for within-group comparisons of dependent variables, while the Mann-Whitney U Test was employed for between-group comparisons of numerical variables, including change ratios and pre- and post-training data. Differences between right and left lower extremities in balance and muscle strength were assessed using the Wilcoxon Signed-Rank Test. Test statistics (z) and p-values are reported. The significance level was set at p < 0.05 for all analyses.

A priori sample size calculation was performed using G*Power software prior to the study. The number of participants included in the study was deemed adequate to achieve sufficient statistical power. Effect sizes (Cohen's d or r) were calculated for primary outcomes to evaluate the magnitude of observed effects. A priori sample size was estimated in G Power (v3.1) for a two-sample t-test, two-tailed, assuming a medium effect (Cohen's d = 0.50), α = 0.05, power = 0.80, and 1:1 allocation, yielding a required n ≈ 128 (64/group). Due to feasibility within a single club, the achieved sample was n = 24 (FIFA 11+ = 13; control = 11). Analyses therefore emphasize estimation; standardized mean differences (Cohen's d) and 95% CIs are reported alongside p-values. For context, with the achieved group sizes a medium effect provides ∼0.22 power; the largest observed effect corresponded to post-hoc power ≈ 0.55–0.58.*

All statistical analyses were performed in consultation with a professional biostatistician to ensure appropriate test selection, assumption checking, and accurate interpretation of result

3 Results

3.1 Participants

The study was designed as a randomized controlled trial involving adolescent amateur male football players. Participants were randomly assigned to either an intervention group receiving the FIFA 11 + program or a control group following their standard warm-up routine. Balance and isokinetic strength assessments were conducted pre- and post-intervention. The male footballers of a team in the Super Amateur League division of Turkey were chosen to participate in this study with a focus on their age range of 15 to 18. At the start of the trial, each participant and their parents signed a pre-informing consent form. External variables such as out-of-session training load, dietary intake, and sleep were not strictly controlled or systematically recorded. Participants were instructed to maintain their usual routines throughout the study period. Baseline characteristics of participants in both groups are shown on Table 1.

To ascertain whether the players were qualified to take part in the study, the eligibility conditions were compared to them. The following requirements had to be met to be included in the study: 1) acceptance of taking part in the case study; 2) age among15 and 17; 3) amateur league soccer experience of at least one year; 4) absence of systemic diseases; and 5) level of mental and physical activity required to successfully complete the tests. The exclusion criteria were as follows: 1) refusal to participate in a case study; 2) severe vision impairment and perceptual problem; 3) testing-preventive discomfort; 4) neurological illnesses; 5) Players who discontinue playing competitive football throughout the research period and interrupt the training regimen by skipping three consecutive sessions; 6) Suffering an injury while conducting the research, and 7) Suffering an injury in the six months before to the study.

Table 1.
Baseline characteristics of participants in both groups.

FIFA 11+ CONTROL

Age,years 16,2 ± 0,9 16,4 ± 0,6

Height,cm 1761 ± 8,6 1777 ± 5,6

Weight,kg 66,6 ± 9,1 67,9 ± 8,4

BWI, kg/m² 21,4 ± 1,8 21,4 ± 2,0

Dominant foot (right), Count 10 10

Dominant foot (left), count 3 1

	FIFA 11+	CONTROL
Age,years	16,2 ± 0,9	16,4 ± 0,6
Height,cm	1761 ± 8,6	1777 ± 5,6
Weight,kg	66,6 ± 9,1	67,9 ± 8,4
BWI, kg/m²	21,4 ± 1,8	21,4 ± 2,0
Dominant foot (right), Count	10	10
Dominant foot (left), count	3	1

* p < 0,05, Q; Quadriceps, H; Hamstring, PT; Peak torque, BW; Body Weight.

Dominant foot was recorded (FIFA 11+: right 10 / left 3; control: right 10 / left 1). Outcomes were analysed side-specifically (left/right). Given the very small number of left-dominant players, additional dominance-adjusted or stratified models were not pre-specified to avoid unstable estimates.

We could not find any significant difference in the body weight, height, age and BMI measurements of the two groups before the training (p > 0,05). Statistically there were not any significant differences between the groups in terms of dominant foot. According to these consequences, there were not any significant differences between right and left quadriceps peak torque values of both groups (p > 0,05). We could not find any significant differences in the right and left hamstring peak torque values between the groups (p > 0,05). Right H / Q ratio of the control group was higher than experimental group (p < 0,05). This difference is due to the fact that the hamstring concentric muscle strength values of the control group were higher than the values of the experimental group before training.

A total of 32 football players agreed to participate; however, five did not meet the eligibility criteria. Consequently, 27 players were enrolled (FIFA 11+: n = 14; control: n = 13). Following the baseline evaluations, three participants withdrew, resulting in a final sample of 24 (FIFA 11+: n = 13; control: n = 11).

Baseline characteristics of participants in both groups are shown on Table 1.

Baseline Measurements: Comparison of Lower Limb Strength, H/Q Ratio, SEBT, between Groups Table 2 shows the results from both groups’ measurements of the concentric peak torque of the hamstrings and quadriceps in the right and left lower extremities and the H/Q ratio at an angular velocity of 60 degrees per second. The right H /Q ratio, however, was larger in the control group than within the experimental group. This discrepancy results from the control group's right hamstring concentric muscle strength values being higher than those of the research group prior to training. Table 2 shows the results from both groups’ measurements of the concentric peak torque of the hamstrings and quadriceps in the right and left lower extremities and the H/Q ratio at an angular velocity of 60 and 240 degrees per second and vertical jump. The two groups did not differ significantly from one another except to the right H / Q ratio (%) at 60 degrees per second (in baseline) that was larger in the control group than in the experimental group and, at 240 degrees per second at Left Q PT (Nm) (in Post 9 Wk) that was larger in the experimental group than in the control group (p = 0042) These results indicated that the left and right quadriceps, hamstring PT, and H/Q ratio measurements of the two groups did not differ significantly from one another. At the baseline evaluation, there was no statistically significant difference between the groups in any of the SEBT result's components (Table 3).

Table 2.

Comparison of right and left lower extremity quadriceps and hamstring concentric peak torque muscle strength and H / Q ratio values at 60 ° and 240 ° / sec angular velocity before and after the intervention.

	Baseline				Post 9 Wk
	Control Group (n = 11) (Mean ± SD)	FIFA 11 + (n = 13) (Mean ± SD)	z	p	Control Group (n = 11) (Mean ± SD)	FIFA 11 + (n = 13) (Mean ± SD)	z	p
60°/sec
Right Q PT (Nm)	1703 ± 43,5	1765 ± 53,2	−,290	,772	1663 ± 48,5	1802 ± 50,1	−,608	,543
Left Q PT (Nm)	1789 ± 42,7	1810 ± 39,8	−,290	,772	1838 ± 47,4	1902 ± 39,4	−,290	,772
Right H PT (Nm)	1355 ± 28,5	1202 ± 26,4	−1334	,182	1382 ± 34,3	1339 ± 25,3	−,000	1000
Left H PT (Nm)	1207 ± 34,4	1170 ± 20,1	−,058	,954	1256 ± 22,2	1253 ± 17,2	−,203	,839
Right Q PT/BW (Nm/kg)	2500 ± 47,4	2673 ± 69,8	−1248	,212	2446 ± 59,3	2734 ± 66,2	−1653	,098
Left Q PT/BW (Nm/kg)	2636 ± 48,7	2750 ± 54,1	−,841	,401	2630 ± 52,2	2899 ± 55,9	−1044	,297
Right H PT/BW (Nm/kg)	2009 ± 36,5	1820 ± 30,8	−,986	,324	2051 ± 46,3	2035 ± 33,8	−,145	,885
Left H PT/BW (Nm/kg)	1778 ± 43,7	1793 ± 19,9	−,261	,794	1873 ± 34,3	1913 ± 24,4	−,203	,839
Right H/Q (%)	81,6 ± 14,4	71,1 ± 15,3	−2146	,032*	87,4 ± 24,6	77,0 ± 17,6	−1130	,258
Left H/Q (%)	67,2 ± 11,4	66,8 ± 17,1	−,609	,543	73,7 ± 18,8	67,8 ± 14,5	−1044	,297
240°/sec
Right Q PT (Nm)	83,7 ± 8,4	88,3 ± 19,1	−,494	,621	83,9 ± 9,2	89,3 ± 19,8	−,319	,750
Left Q PT (Nm)	85,3 ± 14,3	95,0 ± 24,9	−,841	,401	85,8 ± 10,6	1012 ± 21,4	−2030	,042
Right H PT (Nm)	71 ± 19,4	77,3 ± 18,0	−,784	,433	74,6 ± 12,0	80,3 ± 26,6	−,319	,750
Left H PT (Nm)	67,3 ± 14,7	73,5 ± 16,9	−,957	,339	75,3 ± 13,9	78,6 ± 17,4	−,493	,622
Right Q PT/BW (Nm/kg)	1250 ± 21,6	1330 ± 21,1	−,754	,451	1231 ± 17,4	1356 ± 25,3	−1594	,111
Left Q PT/BW (Nm/kg)	1260 ± 12,1	1422 ± 25,1	−1744	,081	1270 ± 17,7	1467 ± 30,6	−1652	,099
Right H PT/BW (Nm/kg)	1054 ± 25,8	1164 ± 19,4	−,958	,338	1107 ± 20,8	1196 ± 41,7	−1072	,284
Left H PT/BW (Nm/kg)	99,0 ± 21,1	1101 ± 18,8	−1594	,111	1130 ± 28,7	1180 ± 22,4	−,493	,622
Right H/Q (%)	85,0 ± 20,2	88,6 ± 13,9	−,406	,685	89,2 ± 15,8	90,4 ± 22,5	−,348	,728
Left H/Q (%)	79 ± 14,43	80,23 ± 19,98	−,116	,908	87,45 ± 12,60	79,31 ± 17,41	−1626	,104

Table 3.

Pre- and post-intervention data for Star excursion balance tests in both experimental and control group.

	FIFA 11 + group				Control group
	Baseline	Post 9 wk			Baseline	Post 9 wk
	Mean ± SD	Mean ± SD	z	p	Mean ± SD	Mean ± SD	z	p
Left Anterior (cm)	63,9 ± 9,4	71,2 ± 8,6	−3182	,001*	67,8 ± 6,1	68,4 ± 6,1	−,890	,374
Right Anterior (cm)	67,0 ± 7,2	72,8 ± 6,4	−3180	,001*	70,3 ± 5,7	70,8 ± 3,5	−,445	,656
Left Anteromedial (cm)	78,4 ± 9,4	81,1 ± 8,7	−2697	,007*	80 ± 8,5	79,0 ± 8,8	−,445	,657
Right Anteromedial (cm)	81,8 ± 9,5	85,3 ± 9,8	−3062	,002*	76,9 ± 6,3	77,9 ± 6,6	−,845	,398
Left Medial (cm)	72,4 ± 7,4	74,9 ± 8,6	−2342	,019*	75,5 ± 5,3	74,4 ± 4,7	−1112	,266
Right Medial (cm)	73,4 ± 9,9	78,2 ± 8,0	−3041	,002*	72,0 ± 9,0	73,0 ± 7,8	−,668	,504
Left Posteromedial (cm)	80,3 ± 8,6	85,0 ± 7,2	−2276	,023*	85,6 ± 9,1	85 ± 8,6	−,667	,504
Right Posteromedial (cm)	82,9 ± 11,1	87,28 ± 9,59	−2971	,003*	82,8 ± 7,8	83,7 ± 7,1	−1246	,213
Left Posterior (cm)	77,9 ± 5,7	80,9 ± 6,1	−2100	,036*	75,0 ± 8,7	76,2 ± 9,9	−1157	,247
Right Posterior (cm)	76,5 ± 8,8	80,6 ± 8,0	−2832	,005*	73,1 ± 9,3	73,6 ± 8,7	−,445	,656
Left Posterolateral (cm)	75,2 ± 12,8	78,6 ± 12,3	−2482	,013*	72,5 ± 12,6	71,6 ± 10,8	−,533	,594
Right Posterolateral (cm)	70,0 ± 13,7	74,0 ± 13,7	−3078	,002*	68,7 ± 10,4	69,8 ± 10,2	−2104	,035*
Left Lateral (cm)	53,0 ± 3,8	55,0 ± 9,0	−1688	,091	51,5 ± 7,09	52,4 ± 6,1	−,757	,449
Right Lateral (cm)	51,4 ± 9,7	55,9 ± 6,5	−2590	,010*	54,5 ± 3,8	54,7 ± 4,4	−,534	,593
Left Anterolateral (cm)	65,8 ± 10,6	69,7 ± 11,0	−2825	,005*	70,0 ± 8,6	69,0 ± 8,1	−1123	,262
Right Anterolateral (cm)	68,7 ± 10,9	73,1 ± 10,2	−2830	,005*	65,8 ± 5,2	66,7 ± 4,6	−,978	,328

3.1.1 Post-Intervention comparison of SEBT and isokinetic strength between groups

The impacts of FIFA 11 + on the angular velocity of 60 °/sec revealed no appreciable changes in the peak torque values of the right and left hamstrings and quadriceps, or in the H/Q (%) ratio, following training. A significant difference was found in the left quadriceps concentric PT in favor of the experimental group, according to the results of the effect of FIFA 11 + on the angular velocity of 240 ° / sec. Additionally, other comparisons showed no significant differences (Table 2). Table 3 shows that there were no significant changes over time in the control group, except for the Right Posterolateral reach distance (cm). In the experimental group, all variables demonstrated significant differences over time, except for the Left Lateral reach distance (cm) (Table 3).

3.1.2 Isokinetic strength between pre- and post-tests

In the experimental group at 60 ° / sec angular velocity, there was only one statistically significant difference between H PT-Right (Nm) and H PT / BW-Right (Nm/kg) comparisons. Similar to how there were no statistically significant variations in other measurements following the intervention, there were also none when comparing the measurements of the control group at 60 angular velocities pre and post-intervention. The measurements of the experimental and control groups at an angular velocity of 240˚/sec pre and post-intervention did not statistically differ significantly.

3.1.3 SEBT between pre- and post-tests

Table 4 shows the results of SEBT measurements from both groups. There were no significant differences between the groups except for a higher right anteromedial reach distance in the experimental group at post 9 weeks. (Table 4).

Table 4.
Comparison of right and left star excursion balance test measurements between groups before and after the intervention.

Baseline Post 9 Wk

Control Group (n = 11) (Mean ± SD) FIFA 11+ (n = 13) (Mean ± SD) Z p Control Group (n = 11) (Mean ± SD) FIFA 11+ (n = 13) (Mean ± SD) z p

Left anterior (cm) 67,8 ± 6,1 63,9 ± 9,4 −,899 ,369 68,4 ± 6,1 71,2 ± 8,6 −,754 ,451

Right anterior (cm) 70,3 ± 5,7 67,0 ± 7,2 −,812 417 70,8 ± 3,5 72,8 ± 6,4 −1277 ,202

Left anteromedial (cm) 80 ± 8,5 78,4 ± 9,4 −,435 ,663 79,0 ± 8,8 81,1 ± 8,7 −,551 ,582

Right anteromedial (cm) 76,9 ± 6,3 81,8 ± 9,5 −1594 ,111 77,9 ± 6,6 85,3 ± 9,8 −2058 ,040

Left medial (cm) 75,5 ± 5,3 72,4 ± 7,4 −1277 ,202 74,4 ± 4,7 74,9 ± 8,6 −,029 ,977

Right medial (cm) 72,0 ± 9,0 73,4 ± 9,9 −,986 ,324 73,0 ± 7,8 78,2 ± 8,0 −1883 ,060

Left posteromedial (cm) 85,6 ± 9,1 80,3 ± 8,6 −1624 ,104 85,0 ± 8,6 85,0 ± 7,2 −,290 772

Right posteromedial (cm) 82,8 ± 7,81 82,9 ± 11,1 −,348 ,728 83,7 ± 7,1 87,2 ± 9,5 −1159 ,246

Left posterior (cm) 75,0 ± 8,7 77,9 ± 5,7 −,579 ,562 76,2 ± 9,9 80,9 ± 6,1 −1101 ,271

Right posterior (cm) 73,1 ± 9,3 76,5 ± 8,8 −,754 ,451 73,6 ± 8,7 80,6 ± 8,0 −1767 ,077

Left posterolateral (cm) 72,5 ± 12,6 75,2 ± 12,8 −,261 ,794 71,6 ± 10,8 78,6 ± 12,3 −1449 ,147

Right posterolateral (cm) 68,7 ± 10,4 70 ± 13,7 −,232 ,817 69,8 ± 10,2 74,0 ± 13,7 −,783 ,434

Left lateral (cm) 51,5 ± 7,0 54,0 ± 7,8 −,348 ,728 52,4 ± 6,1 55,0 ± 9,0 −,899 ,369

Right lateral (cm) 54,5 ± 3,8 51,4 ± 9,7 −,956 ,339 54,7 ± 4,4 55,9 ± 6,6 −,609 ,542

Left anterolateral (cm) 70,0 ± 8,6 65,8 ± 10,6 −,986 ,324 69,0 ± 8,1 69,7 ± 11,0 −,261 ,794

Right anterolateral (cm) 65,8 ± 5,2 68,7 ± 10,9 −,116 ,908 66,7 ± 4,6 73,1 ± 10,2 −1914 ,056

	Baseline	Post 9 Wk
Left anterior (cm)	67,8 ± 6,1	63,9 ± 9,4	−,899	,369	68,4 ± 6,1	71,2 ± 8,6	−,754	,451
Right anterior (cm)	70,3 ± 5,7	67,0 ± 7,2	−,812	417	70,8 ± 3,5	72,8 ± 6,4	−1277	,202
Left anteromedial (cm)	80 ± 8,5	78,4 ± 9,4	−,435	,663	79,0 ± 8,8	81,1 ± 8,7	−,551	,582
Right anteromedial (cm)	76,9 ± 6,3	81,8 ± 9,5	−1594	,111	77,9 ± 6,6	85,3 ± 9,8	−2058	,040
Left medial (cm)	75,5 ± 5,3	72,4 ± 7,4	−1277	,202	74,4 ± 4,7	74,9 ± 8,6	−,029	,977
Right medial (cm)	72,0 ± 9,0	73,4 ± 9,9	−,986	,324	73,0 ± 7,8	78,2 ± 8,0	−1883	,060
Left posteromedial (cm)	85,6 ± 9,1	80,3 ± 8,6	−1624	,104	85,0 ± 8,6	85,0 ± 7,2	−,290	772
Right posteromedial (cm)	82,8 ± 7,81	82,9 ± 11,1	−,348	,728	83,7 ± 7,1	87,2 ± 9,5	−1159	,246
Left posterior (cm)	75,0 ± 8,7	77,9 ± 5,7	−,579	,562	76,2 ± 9,9	80,9 ± 6,1	−1101	,271
Right posterior (cm)	73,1 ± 9,3	76,5 ± 8,8	−,754	,451	73,6 ± 8,7	80,6 ± 8,0	−1767	,077
Left posterolateral (cm)	72,5 ± 12,6	75,2 ± 12,8	−,261	,794	71,6 ± 10,8	78,6 ± 12,3	−1449	,147
Right posterolateral (cm)	68,7 ± 10,4	70 ± 13,7	−,232	,817	69,8 ± 10,2	74,0 ± 13,7	−,783	,434
Left lateral (cm)	51,5 ± 7,0	54,0 ± 7,8	−,348	,728	52,4 ± 6,1	55,0 ± 9,0	−,899	,369
Right lateral (cm)	54,5 ± 3,8	51,4 ± 9,7	−,956	,339	54,7 ± 4,4	55,9 ± 6,6	−,609	,542
Left anterolateral (cm)	70,0 ± 8,6	65,8 ± 10,6	−,986	,324	69,0 ± 8,1	69,7 ± 11,0	−,261	,794
Right anterolateral (cm)	65,8 ± 5,2	68,7 ± 10,9	−,116	,908	66,7 ± 4,6	73,1 ± 10,2	−1914	,056

In the pre- and post-training comparison of the star excursion balance test, the study group showed only one statistically significant difference, in all directions except the left lateral measurement, while the control group showed a significant difference only in the right posterolateral measurement ; no significant differences were found in the other measurements in either group (Table 5).

Table 5.

Pre and post training comparisons of the star excursion test.

	FIFA 11 + group				Control group
	Baseline	Post 9 wk			Baseline	Post 9 wk
	Mean ± SD	Mean ± SD	z	p	Mean ± SD	Mean ± SD	z	p
Left Anterior (cm)	63,9 ± 9,4	71,2 ± 8,6	−3182	,001*	67,8 ± 6,1	68,4 ± 6,1	−,890	,374
Right Anterior (cm)	67,0 ± 7,2	72,8 ± 6,4	−3180	,001*	70,3 ± 5,7	70,8 ± 3,5	−,445	,656
Left Anteromedial (cm)	78,4 ± 9,4	81,1 ± 8,7	−2697	,007*	80 ± 8,5	79,0 ± 8,8	−,445	,657
Right Anteromedial (cm)	81,8 ± 9,5	85,3 ± 9,8	−3062	,002*	76,9 ± 6,3	77,9 ± 6,6	−,845	,398
Left Medial (cm)	72,4 ± 7,4	74,9 ± 8,6	−2342	,019*	75,5 ± 5,3	74,4 ± 4,7	−1112	,266
Right Medial (cm)	73,4 ± 9,9	78,2 ± 8,0	−3041	,002*	72,0 ± 9,0	73,0 ± 7,8	−,668	,504
Left Posteromedial (cm)	80,3 ± 8,6	85,0 ± 7,2	−2276	,023*	85,6 ± 9,1	85 ± 8,6	−,667	,504
Right Posteromedial (cm)	82,9 ± 11,1	87,2 ± 9,5	−2971	,003*	82,8 ± 7,8	83,7 ± 7,1	−1246	,213
Left Posterior (cm)	77,9 ± 5,7	80,9 ± 6,1	−2100	,036*	75,0 ± 8,7	76,2 ± 9,9	−1157	,247
Right Posterior (cm)	76,5 ± 8,8	80,6 ± 8,0	−2832	,005*	73,1 ± 9,3	73,6 ± 8,7	−,445	,656
Left Posterolateral (cm)	75,2 ± 12,8	78,6 ± 12,3	−2482	,013*	72,5 ± 12,6	71,6 ± 10,8	−,533	,594
Right Posterolateral (cm)	70,0 ± 13,7	74,0 ± 13,7	−3078	,002*	68,7 ± 10,4	69,8 ± 10,2	−2104	,035*
Left Lateral (cm)	53,0 ± 3,8	55,0 ± 9,0	−1688	,091	51,5 ± 7,0	52,4 ± 6,1	−,757	,449
Right Lateral (cm)	51,4 ± 9,7	55,9 ± 6,5	−2590	,010*	54,5 ± 3,8	54,7 ± 4,4	−,534	,593
Left Anterolateral (cm)	65,8 ± 10,6	69,7 ± 11,0	−2825	,005*	70,0 ± 8,6	69,0 ± 8,1	−1123	,262
Right Anterolateral (cm)	68,7 ± 10,9	73,1 ± 10,2	−2830	,005*	65,8 ± 5,2	66,7 ± 4,6	−,978	,328

As a resukt for Isokinetic strength, at baseline, groups were generally comparable, except for Right H/Q at 60°/s, which was higher in the FIFA 11 + group (see Baseline Table). After nine weeks, between-group differences were non-significant for most strength outcomes. An exception was Left Quadriceps Peak Torque at 240°/s, where the FIFA 11 + group demonstrated higher values than controls (101.23 ± 21.41 vs 85.82 ± 10.65 Nm; p = 0.042; Cohen's d≈0.887). No other post-intervention contrasts reached significance. And for Dynamic balance (SEBT); Post-intervention, the FIFA 11 + group outperformed controls in Right anteromedial reach (85.39 ± 9.88 vs 77.95 ± 6.65 cm; p = 0.040; Cohen's d≈0.869). Differences in other directions did not achieve statistical significance (e.g., Right medial, p = 0.060, d≈0.66; Right anterolateral, p = 0.056, d≈0.78). To facilitate clinical interpretation, standardized mean differences (Cohen's d and Hedges' g) were calculated for all outcomes and are available from the corresponding author upon reasonable request.

Several methodological factors qualify the interpretation of our findings. First, the study was likely underpowered for detecting small-to-moderate between-group effects: with n = 13 (FIFA 11+) versus n = 11 (control) and α=0.05 (two-sided), a medium effect (Cohen's d≈0.50) affords only ∼0.22 power, whereas a large effect (d≈0.80) yields ∼0.46. This limitation may partly explain the predominance of non-significant post-intervention differences despite within-group improvements. Second, a baseline imbalance in Right H/Q at 60°/s was present, which underscores the value of adjusting post-intervention analyses for baseline (e.g., ANCOVA or change-score models). In sensitivity analyses that assumed plausible baseline–post correlations (r = 0.3–0.7), the effective power increased substantively under ANCOVA, suggesting that baseline adjustment can enhance precision. Third, multiple outcome testing was not formally adjusted, so isolated significant findings should be interpreted cautiously and contextualized with effect sizes and confidence intervals. Collectively, these considerations indicate that the absence of consistent between-group differences does not rule out clinically relevant effects. Future trials should pre-specify a single primary endpoint, record baseline–post correlations, and enroll approximately 30 participants per group to achieve ∼80% power for medium effects.

4 Discussion

The peak torque values of the quadriceps and hamstring at an angular velocity of 60 °/sec before and after the intervention in this investigation didn't differ statistically significantly. At an angular velocity of 240°/sec, only the left quadriceps concentric peak torque value was statistically significant when compared to the experimental and control groups. The data we found was consistent with a few research in the literature. After the training, the groups’ rates of development in both angular velocities were compared, and although statistically no differences were found, the groups were stated to have improved for 9 weeks. In this investigation, we found that the F 11 + program alone had no effect on the isokinetic muscle strength. Previous studies examining the effects of the FIFA 11 + program on knee muscle strength have reported mixed findings, with some studies showing modest improvements and others reporting no significant changes, particularly in short-term interventions and amateur or youth populations^14,16,26,27 Other studies involving senior professional football players also reported positive results in strength ratios, quadriceps, hamstrings, isometric strength, and concentric hamstring strength.^26,28

Our analysis revealed that the control group had a higher H/Q ratio compared to the experimental group at baseline. However, this difference disappeared after the intervention. Consistent with our hypothesis, the experimental group exhibited a 12% increase in hamstring peak torque, whereas the control group showed a 1% decrease following the intervention. Consequently, no significant difference in H/Q ratios between the groups was observed post-training. When comparing the baseline H/Q ratio values at an angular velocity of 60°/sec with existing literature, the values in our experimental group were similar to those reported by Carvalho et al.experimental groupexperimental group.²⁹

The Star Excursion Balance Test (SEBT) is widely used in both clinical and sporting settings to assess dynamic postural control of the lower extremity.³⁰ In the present study, the FIFA 11 + group demonstrated improvements across all SEBT directions, with the greatest increase observed in the left anterior reach distance (approximately 11%). These findings suggest that the FIFA 11 + program may enhance dynamic balance through neuromuscular adaptations related to postural control and coordination. Improvements in SEBT performance following the FIFA 11 + program are consistent with previous studies reporting positive effects on dynamic balance in youth and amateur football players^2,11–14 According to Leavey et al., six weeks of combined strength and balance training can improve dynamic control of posture (as measured by SEBT) in healthy males and females.³¹ McKeon et al. found that dynamic modulation of posture was better after 4 weeks of balance training. They emphasized that this improvement might be related to a reduction in sensorimotor system restrictions brought on by balance training.³²

Biological maturation has been shown to influence strength and neuromas cular adaptations in adolescent soccer players. Studies by Perroni et al. and Kırmızıgil et al. indicate that athletes of the same chronological age may differ substantially in physical performance due to differences in maturational status.^33,34 Although pubertal status was not directly assessed in the present study, such differences may partly explain the variability in isokinetic strength outcomes observed after the intervention. In contrast, the consistent improvements in dynamic balance may reflect neuromuscular adaptations that are less dependent on biological maturation and more responsive to coordination-based training, such as the FIFA 11 + program.

Several limitations should be acknowledged. External factors such as training load outside the intervention, nutrition, and sleep were not strictly controlled and may have influenced individual responses. Participants were not blinded to group allocation, which may have introduced motivational bias. Furthermore, although left and right limbs were analysed separately, limb dominance was not formally classified, which may have influenced the observed variability in performance outcomes.The intervention period was limited to nine weeks and the sample was drawn from a single amateur team, which may restrict generalisability to other settings. In addition, pubertal status and limb dominance were not formally assessed and may have contributed to variability in performance outcomes. Finally, the modest sample size may have limited the ability to detect small but potentially meaningful between-group differences. Future studies with larger, multi-centre samples and longer intervention periods are warranted

5 Conclusions

This study demonstrated that the FIFA 11 + program produced limited improvements in isokinetic knee muscle strength but led to meaningful gains in dynamic balance in adolescent amateur football players. These findings suggest that the program primarily enhances neuromuscular control rather than muscle strength when implemented as a standalone warm-up.

From a practical perspective, FIFA 11 + represents a feasible and time-efficient warm-up strategy for amateur youth teams, requiring minimal equipment and resources. However, if muscle strength development is a primary objective, the program should be complemented with additional, targeted resistance training.

Given the limited evidence available for adolescent amateur football players, the present findings contribute to the understanding of performance-related adaptations to injury prevention programs in this population and support the use of FIFA 11 + to improve balance and potentially reduce injury risk.

6 Clinical implications

Our study found that the 11 + program had limited effects on isokinetic muscle strength in amateur football players, with no statistically significant improvements observed in most strength measures. However, notable improvements were seen in dynamic balance performance, suggesting that the program may be more effective for enhancing neuromuscular control rather than muscle strength alone. As a clinical implication For adolescent amateur teams, FIFA 11 + can be used as the standard warm-up 3×/week in 15–20 min (10–12 min when condensed) with minimal cost (cones/markers). Emphasize movement quality (knee alignment, soft landings), progress difficulty every 2–3 weeks, and track attendance. Common barriers—time, buy-in, coach familiarity, space—are manageable by replacing the old warm-up (not adding to it), rotating player leaders, providing a one-page cue sheet + brief demos, and running two parallel lanes in small areas. If performance gains are a priority, add brief hip/knee strengthening after the warm-up 2×/week. The lack of consistent strength gains likely reflects both the 9-week exposure and the programme's emphasis on neuromuscular control rather than high-load, progressive resistance; as a brief warm-up, FIFA 11 + is not designed to induce hypertrophy or maximal strength, and longer exposure and/or adjunct resistance training may be required.

Footnotes

ORCID iD

Feyza Sule Badilli Hantal

Ethical approval

The Helsinki Declaration and ethical guidelines were followed during the study's execution. The Clinical Research Ethics Committee approved the study plan at a meeting on September 26, 2018, with registration number 1522.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Data availability statement

The data that support the findings of this study are available on request from the corresponding author, [initials]. The data are not publicly available due to [restrictions e.g., their containing information that could compromise the privacy of research participants].

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	Baseline				Post 9 Wk
	Control Group (n = 11) (Mean ± SD)	FIFA 11+ (n = 13) (Mean ± SD)	Z	p	Control Group (n = 11) (Mean ± SD)	FIFA 11+ (n = 13) (Mean ± SD)	z	p
Left anterior (cm)	67,8 ± 6,1	63,9 ± 9,4	−,899	,369	68,4 ± 6,1	71,2 ± 8,6	−,754	,451
Right anterior (cm)	70,3 ± 5,7	67,0 ± 7,2	−,812	417	70,8 ± 3,5	72,8 ± 6,4	−1277	,202
Left anteromedial (cm)	80 ± 8,5	78,4 ± 9,4	−,435	,663	79,0 ± 8,8	81,1 ± 8,7	−,551	,582
Right anteromedial (cm)	76,9 ± 6,3	81,8 ± 9,5	−1594	,111	77,9 ± 6,6	85,3 ± 9,8	−2058	,040
Left medial (cm)	75,5 ± 5,3	72,4 ± 7,4	−1277	,202	74,4 ± 4,7	74,9 ± 8,6	−,029	,977
Right medial (cm)	72,0 ± 9,0	73,4 ± 9,9	−,986	,324	73,0 ± 7,8	78,2 ± 8,0	−1883	,060
Left posteromedial (cm)	85,6 ± 9,1	80,3 ± 8,6	−1624	,104	85,0 ± 8,6	85,0 ± 7,2	−,290	772
Right posteromedial (cm)	82,8 ± 7,81	82,9 ± 11,1	−,348	,728	83,7 ± 7,1	87,2 ± 9,5	−1159	,246
Left posterior (cm)	75,0 ± 8,7	77,9 ± 5,7	−,579	,562	76,2 ± 9,9	80,9 ± 6,1	−1101	,271
Right posterior (cm)	73,1 ± 9,3	76,5 ± 8,8	−,754	,451	73,6 ± 8,7	80,6 ± 8,0	−1767	,077
Left posterolateral (cm)	72,5 ± 12,6	75,2 ± 12,8	−,261	,794	71,6 ± 10,8	78,6 ± 12,3	−1449	,147
Right posterolateral (cm)	68,7 ± 10,4	70 ± 13,7	−,232	,817	69,8 ± 10,2	74,0 ± 13,7	−,783	,434
Left lateral (cm)	51,5 ± 7,0	54,0 ± 7,8	−,348	,728	52,4 ± 6,1	55,0 ± 9,0	−,899	,369
Right lateral (cm)	54,5 ± 3,8	51,4 ± 9,7	−,956	,339	54,7 ± 4,4	55,9 ± 6,6	−,609	,542
Left anterolateral (cm)	70,0 ± 8,6	65,8 ± 10,6	−,986	,324	69,0 ± 8,1	69,7 ± 11,0	−,261	,794
Right anterolateral (cm)	65,8 ± 5,2	68,7 ± 10,9	−,116	,908	66,7 ± 4,6	73,1 ± 10,2	−1914	,056

The effects of FIFA 11+ exercise program on balance and isokinetic muscle strength on adolescent amateur soccer players

Abstract

Background

Methods

Results

Conclusion

Clinical relevance

Keywords

1 Introduction

2 Methods

2.1 Procedure

2.2.1 Balance assessment

2.2.2 Isokinetic assessment

2.3 Intervention

2.4 Statistical analysis

3 Results

3.1 Participants

Table 1. Baseline characteristics of participants in both groups. FIFA 11+ CONTROL Age,years 16,2 ± 0,9 16,4 ± 0,6 Height,cm 1761 ± 8,6 1777 ± 5,6 Weight,kg 66,6 ± 9,1 67,9 ± 8,4 BWI, kg/m2 21,4 ± 1,8 21,4 ± 2,0 Dominant foot (right), Count 10 10 Dominant foot (left), count 3 1

3.1.2 Isokinetic strength between pre- and post-tests

3.1.3 SEBT between pre- and post-tests

5 Conclusions

6 Clinical implications

Footnotes

ORCID iD

Ethical approval

Funding

Declaration of conflicting interests

Data availability statement

References

Table 1.
Baseline characteristics of participants in both groups.

FIFA 11+ CONTROL

Age,years 16,2 ± 0,9 16,4 ± 0,6

Height,cm 1761 ± 8,6 1777 ± 5,6

Weight,kg 66,6 ± 9,1 67,9 ± 8,4

BWI, kg/m² 21,4 ± 1,8 21,4 ± 2,0

Dominant foot (right), Count 10 10

Dominant foot (left), count 3 1