Physical preparation and injury prevention

The 11+: what works, what does not

The FIFA 11+ is the best-evidenced warm-up in any team sport. Its pooled effect is nevertheless smaller — and shakier — than clubs believe. Thorborg's meta-analysis (BJSM 2017;51:562-571) did the one thing that matters: it separated the 11+ from its predecessor, "the 11".

The foundational trial, and the detail federation summaries leave out

Soligard et al., BMJ 2008;337:a2469. Cluster-randomised trial, 1,892 female players aged 13-17, 125 Norwegian clubs (65 intervention clusters, 60 control), one league season. 264 players sustained a relevant injury, 121 intervention vs 143 control.

The three published nulls

• Steffen 2008 (Scand J Med Sci Sports) — "the 11" in 113 Norwegian female youth teams, 2,092 players: RR 1.0 (0.8-1.2), p=0.94. Only 14 of the 58 intervention teams completed more than 20 prevention sessions.
• van Beijsterveldt 2012 (BJSM) — "The11" in Dutch adult male amateurs, 23 teams, 456 players: 9.6 vs 9.7 injuries per 1000 h, no difference, despite 73% team and 71% player compliance. The one signal was significantly fewer knee injuries. Its companion economic analysis (Krist, J Physiother 2013) found costs of €161 vs €361 per athlete, mean difference €201 (95% CI 15-426) in favour of the intervention.
• Hammes 2015 (J Sports Sci) — FIFA 11+ in veteran male players (mean age 43-45), 20 teams, n=265: overall IRR 0.91 (0.64-1.48), p=0.89. Only severe injuries reached significance, IRR 0.46 (0.21-0.97), p=0.04. The authors attributed the null to low training frequency.

Compliance outweighs the programme

This is the finding coaches actually need: the gap between doing it properly and doing it half-heartedly is larger than the gap between doing it and not doing it.

• In the foundational Norwegian cohort (Soligard, BJSM 2010): teams completed the programme in 77% of sessions (mean 1.3 per week), players in 79% of the sessions they attended (mean 0.8 per week). High vs intermediate compliance: RR 0.65 (0.46-0.91), p=0.011. Coaches who had previously used injury-prevention training had teams at OR 0.54 (0.33-0.87).
• In Canada (Steffen, BJSM 2013), in youth female players: high adherers showed IRR 0.28 (0.10-0.79).
• For ACL specifically (Sugimoto, J Athl Train 2012, 6 studies): high vs low compliance IRR 0.27 (0.07-0.80); tertile analysis IRR 0.18 (0.02-0.77). The authors describe "a potential inverse dose-response relationship".
• And over time: Magoshi 2026 (non-randomised controlled trial, 763 female collegiate Japanese players, 7 teams) — one season of the 11+ produced no significant difference; three consecutive seasons produced non-contact ACL HR 0.192 (0.041-0.896), p=0.036 in the 128 players followed throughout. The 11+ looks like a multi-season dose, not a single-season fix.

11+ Kids: ages 7 to 13

This is the strongest paediatric result in the whole of football. Rössler et al., Sports Medicine 2018;48:1493-1504: cluster-randomised trial, n=3,895 children aged 7-13 (mean 10.8 ± 1.4 years), across Switzerland, Germany, the Czech Republic and the Netherlands, 292,749 exposure hours, one season.

• Overall injury: HR 0.52 (0.32-0.86)
• Severe injury: HR 0.26 (0.10-0.64)
• Lower extremity: HR 0.45 (0.24-0.84)

The content, as the FIFA manual publishes it: 7 exercises, 5 difficulty levels each — an "Alertness" running game; skating jumps; single-leg stance; press-ups; single-leg jumps; Spiderman; sideways roll (so the programme contains one falling-technique exercise). Duration 15 to 20 minutes once familiar; at least once a week, twice a week recommended for greater protective benefit.

Hamstrings and adductors

The Nordic hamstring exercise: proven, and massively not done

• The effect: van Dyk, BJSM 2019, meta-analysis of 15 studies and 8,459 athletes — RR 0.49 (0.32-0.74), p=0.0008; 0.52 (0.32-0.85) with RCTs only; 0.55 (0.34-0.89), p=0.006 after removing the 8 studies at high risk of bias. In the authors' words, programmes that include the Nordic hamstring exercise halve the rate of hamstring injuries.
• In professionals: Petersen, AJSM 2011 — 50 Danish male teams, 942 players, a 10-week progressive eccentric programme then weekly maintenance: 3.8 vs 13.1 acute hamstring injuries per 100 player-seasons, adjusted RR 0.293 (0.150-0.572), p<0.001; NNT 13 (9-23) overall, 3 (2-6) for recurrences.
• In amateurs: van der Horst, AJSM 2015 — 40 Dutch amateur teams, 579 male players, 25 sessions over 13 weeks: OR 0.282 (0.110-0.721), p=0.005, compliance 91%. Note the limit: no reduction in the severity of the injuries that did occur.
• Adoption: Bahr, BJSM 2015 — a survey of 150 club-seasons (32 Champions League teams, 18 Norwegian Tippeligaen teams, 100% response): the programme was completed in full in 16 club-seasons (10.7%), in part in 9 (6%), and 125 (83.3%) were non-compliant. The authors' own conclusion: adoption is "too low to expect any overall effect on acute hamstring injury rates".
• It is not a screening test. Opar, Sports Medicine 2021, meta-analysis of 6 prospective cohorts, 1,100 participants (156 injured / 944 uninjured): pre-season eccentric knee-flexor strength measured during the Nordic hamstring exercise did not distinguish future-injured from uninjured players — not in absolute terms, not relative to body mass, not as between-limb asymmetry. Doing the exercise is the intervention; measuring the exercise is not.

Adductors: the Copenhagen exercise, and a gap in the 11+

• The protocol: the Adductor Strengthening Programme — one exercise, three progression levels, 3 times a week through a 6-8 week pre-season, then once a week for the 28-week competitive season.
• The effect: Harøy, BJSM 2019 — 35 semi-professional Norwegian teams, 652 players. Average in-season prevalence of groin problems: 13.5% (12.3-14.7) vs 21.3% (20.0-22.6), OR 0.59 (0.40-0.86), p=0.008. The outcome is a weekly problem prevalence measured with the OSTRC questionnaire — it is not comparable to the time-loss incidence rates elsewhere on this page.
• The gap in the 11+: Harøy, AJSM 2017 — the standard FIFA 11+ produces no change in eccentric hip adduction strength (−0.02 N·m/kg, i.e. −0.7%, p=0.69), whereas substituting the Copenhagen adduction exercise gives +0.29 N·m/kg (+8.9%), p=0.01. That is a concrete, citable gap in the 11+ as published.
• What actually happens on the pitch: of 501 players surveyed, 91% believed such a programme would reduce groin injury risk and 73% finished it in under 5 minutes — but only 46% performed it as recommended and only 31% intended to continue the following season. Among 29 delivery staff at Norwegian professional clubs, 100% had adopted the programme and 10% used the original protocol.

Heading: five federations, four units

This is the section coaches most need, and the one where it is most tempting to pick a winner. Do not. Five bodies publish a position, they regulate four different quantities, and only two have made it a refereeable law.

• The age boundary genuinely differs: U9 in France, U11 in the USA, a phased withdrawal from U7 to U11 in England, 11s then 12s in Scotland. It cannot be modelled as one rule.
• The Scottish FA is the only body that instructs on ball inflation pressure: "Don't over inflate the footballs: use the lowest pressure authorised by the Laws of the Game." (13s and above.) IFAB Law 2 gives a pressure range, not an instruction to minimise it.
• The widely reported "no heading under 12 in Scotland" framing is wrong: it is a seven-band graduated ladder running to 17s, and it applies to training only. The Scottish document carries no publication date on its face — only the statement that it applies "with immediate effect".
• The FFF framework is the newest: the digital booklet "Jeu de tête" was published on 16 December 2025 and relayed by a district on 7 April 2026. It is also the only one that caps time rather than repetitions.
• Switzerland did not forget to legislate. Patrick Bruggmann, the ASF's director of football development, publicly calls a ban "wenig sinnvoll" (of little use), and the same report (1 February 2023) records that "Richtlinien für den Breiten- oder Profifussball gibt es hierzulande keine, Verbote im Juniorenfussball auch nicht." — there are no guidelines here for grassroots or professional football, and no bans in junior football either. Swiss sports medicine describes the same state of play: heading is banned for children in England and the USA, "in Deutschland und der Schweiz aber nicht" (SEMS-journal, 24 October 2022).

And the question parents ask

The FIELD study (Mackay, New England Journal of Medicine 2019) is the most cited and most distorted figure on the subject. Retrospective cohort, 7,676 former Scottish professional players vs 23,028 matched controls, median 18 years of follow-up: neurodegenerative disease as primary cause of death 1.7% vs 0.5%, subhazard ratio 3.45 (95% CI 2.11-5.62), p<0.001; Alzheimer's HR 5.07 (2.92-8.82); Parkinson's HR 2.15 (1.17-3.96). But also: all-cause mortality was lower in players up to age 70, ischaemic heart disease HR 0.80 (0.66-0.97), lung cancer HR 0.53 (0.40-0.70).

What the study measured was playing professional football — not heading. The only available proxy for heading exposure is goalkeepers vs outfield players, and it is equivocal: neurodegenerative mortality HR 0.73 (0.43-1.24), p=0.24 — no difference — but dementia-medication prescribing OR 0.41 (0.19-0.89) — less. The two results point in different directions and both should be printed. The authors themselves write that their observations "need to be confirmed in prospective matched-cohort studies".

Framing rule: the evidence supports precaution about cumulative head impacts in children and a strict concussion protocol at every level. It does not support telling a parent that heading causes dementia. Say both sentences, or neither.

Concussion

Here too the texts diverge, and the divergence is between a national federation and the international consensus — not between one expert and another.

The divergence to print: the FFF prescribes 48 h of complete rest where Amsterdam prescribes relative — explicitly not strict — rest for up to 2 days, with light activity encouraged from 24-48 h. And the FFF floor of 3 weeks for under-20s has no international equivalent. This is not a translation nuance: it is a real disagreement between a national federation and the global consensus, and a French club is bound by the French text.

Load, growth and strength training

Growth and the growth spurt

• The risk is real, but the literature contradicts itself. Monasterio (Int J Sports Med 2023, one elite academy, 124 players, longitudinal heights 2000-2020): around peak height velocity, a fast spurt versus an average one gives an overall injury burden of 2.6× (1.4-4.8), versus a slow one 3.3× (1.3-6.7); growth-related injury burden 2.9× (1.1-7.1) and 4.1× (1.4-15.2).
• But the 2025 systematic review (Health Sci Rep, 12 studies) rates the certainty of evidence very low and could not meta-analyse: burden is highest circa-PHV in 5 studies and post-PHV in 2.
• And one large case-control study found no effect at all: growth rate 4.8 cm per year in both injured and uninjured athletes, p=0.96 (Jayanthi, AJSM 2015, n=1,190).
• Maturity estimates fail exactly where they are needed. Malina (Am J Hum Biol 2021, 266 boys aged 8-17 and 147 girls aged 8-16): predicted maturity offset and predicted age at PHV increase with the chronological age at prediction, show reduced variance compared with observed values, and have "major limitations with early and late maturing boys and girls" — predictions were later than observed in early maturers and earlier in late maturers.
• Bio-banding (grouping by maturity rather than chronological age) "reduces, but does not eliminate, maturity-associated variation", and "the currently used height prediction equation requires further evaluation" (Malina, Sports Medicine 2019).

Youth strength training: the myth, in writing

From the 2014 International Consensus position statement on youth resistance training (Lloyd, Faigenbaum, Stone et al., BJSM 2014;48:498-505):

• "Fears that resistance training would injure the growth plates of youths are not supported by scientific reports or clinical observations."
• "No scientific evidence indicates that resistance training will have an adverse effect on linear growth during childhood or adolescence or reduce eventual height."
• Children as young as 5-6 years make noticeable improvements in muscular fitness; the criterion is readiness, not age — being "emotionally mature enough to accept and follow directions" and possessing competent balance and postural control. Programmes require qualified professionals.
• 2-3 sessions per week on non-consecutive days. Beginners: 1-2 sets at ≤60% of 1RM. Developing: 2-4 sets of 6-12 repetitions at ≤80% of 1RM. Advanced: ≤6 repetitions above 85% of 1RM, only with demonstrated technical competency. Prescription is based on training age and motor competence, not chronological age.

One published circuit, with its stated age: the Swiss federal office of sport (mobilesport.ch) publishes a Konditions-Circuittraining Fussball: Kraft stated for 16 to 20 years, "advanced and accomplished" — 12 stations, 45 s work / 45 s transition, 2-3 circuits. The stations: half squat (bar, no added weight, straight back) · oblique abdominals (the head never touches the ground) · hamstrings · press-ups · skipping rope · quadriceps (single leg, 90° maximum) · adductors · straight abdominals (seated, dynamic) · jumps onto a bench · back (alternating arm and leg) · calves · skipping.

Volume and early specialisation

• Jayanthi 2015 (AJSM), clinical case-control, 1,190 athletes aged 7-18 (822 injured / 368 uninjured): sport specialisation → any injury OR 1.27 (1.07-1.52), p<0.01; serious overuse injury OR 1.36 (1.08-1.72); more hours of organised sport per week than years of age → OR 2.07 (1.40-3.05), p<0.001; organised sport to free play ratio above 2:1 → OR 1.87 (1.26-2.76).
• "Weekly hours should not exceed age in years" is the only quantitative rule of thumb in this section with a published odds ratio behind it — but it comes from a case-control design at level of evidence 3, in a mixed-sport clinical population, not a football cohort. Label it accordingly.
• No federation cap on weekly training volume by age category was retrieved — not from the FFF, not from the ASF/SFV, not from the URBSFA. That is an open question, not a finding of absence.

Small-sided games or running: the evidence does not decide

Zhang 2026 (BMC Sports Sci Med Rehabil), 17 RCTs, 402 male adolescent team-sport athletes aged 10-19: no between-group difference for VO₂max (SMD 0.05, −0.28 to 0.39), VIFT (0.24, −0.08 to 0.56), countermovement jump (0.02, −0.24 to 0.28), sprint ≤10 m (−0.11, −0.38 to 0.16) or ≥20 m (−0.14, −0.39 to 0.11), or change of direction (0.00, −0.45 to 0.45). HIIT is superior only on the Yo-Yo IR1: SMD 0.42 (0.09-0.74). In female players, Trotta 2025 (Br Med Bull) finds small-sided games superior for change of direction with no difference elsewhere, while stating that "limited and heterogeneous data … prevent definitive conclusions". The usable conclusion: for the fitness qualities that matter to a youth football team, small-sided games and running-based HIIT are broadly interchangeable — and because small-sided games also deliver technical and tactical content in the same minutes, the sport-science evidence does not require a club to run laps.

What a grassroots club can actually do

Working assumption: a volunteer coach, about 18 children, two 90-minute sessions a week, no medical staff, no GPS, no gym.

1. 11+ Kids as the warm-up, twice a week, every week, for 7-13-year-olds. 7 exercises, 5 levels, 15-20 min, no equipment — and the only children's football programme with a multinational cluster-randomised trial behind it (HR 0.52 overall, 0.26 for severe injuries).
2. The FIFA 11+ as the warm-up from about 14 upwards, twice a week, parts 1 and 3 only before matches. The age is stated by FIFA, the frequency by F-MARC.
3. A written concussion rule: no same-day return, 48 to 72 hours of observation, no return without a doctor. FIFA makes it a hard rule at every level and it costs nothing to adopt; in France the under-20 floor is 3 weeks.
4. Whichever national heading rule applies to you, exactly as written. These are rules, not options — except in Switzerland, where there are none, deliberately.
5. Small-sided games instead of laps. Same effect on VO₂max, sprint, jump and change of direction, with the technical content thrown in.
6. For post-pubertal squads: the Nordic hamstring exercise and the Copenhagen adduction exercise — knowing that the trials were run in adult men and that no paediatric trial exists for either.

And what not to import from the professional game:

• Any risk score derived from a workload ratio — not validated at any level.
• GPS-derived high-speed running targets — match-to-match variability is 37.6% to 69.0% in professional women; a single match measures nothing.
• Eccentric hamstring strength testing as a screen — it does not distinguish future-injured players (1,100 athletes).
• Maturity-offset dashboards and bio-banding by predicted adult height — the predictions fail precisely for early and late maturers.
• Benchmarking your club's injury rate against elite per-1000-h rates. Definitions, medical staffing and reporting are not comparable: elite men 8.0/1000 h, elite women 6.7/1000 h, high-level male youth 5.8/1000 h (3.7 for U9-U16) — but Dutch adult amateurs 9.6/1000 h (8.7-10.5). The measured amateur rate is higher than the elite rate, and that is not a rounding error: it is exactly why the comparison is meaningless.

Sources

Programmes and trials: Soligard et al., BMJ 2008;337:a2469 · Thorborg et al., BJSM 2017;51:562-571 · Sadigursky et al., BMC Sports Sci Med Rehabil 2017;9:18 · Soligard et al., BJSM 2010;44:787-793 · Steffen et al., BJSM 2013;47:794-802 · Steffen et al., Scand J Med Sci Sports 2008;18:605-614 · van Beijsterveldt et al., BJSM 2012;46:1114-1118 · Krist et al., J Physiother 2013;59:15-23 · Hammes et al., J Sports Sci 2015;33:873-881 · Rössler et al., Sports Medicine 2018;48:1493-1504 · Al Attar et al., Am J Sports Med 2021;49:2293-2300 (confidence intervals not quotable — an internal defect of the paper) · Magoshi et al., J Sports Med Phys Fitness 2026;66 · Sugimoto et al., J Athl Train 2012;47:714-723 · FIFA / F-MARC 11+, 11+ Kids and 11+ Referee manuals (mirrored copies).
Muscle: Petersen et al., Am J Sports Med 2011;39:2296-2303 · van der Horst et al., Am J Sports Med 2015;43:1316-1323 · van Dyk et al., BJSM 2019;53:1362-1370 · Opar et al., Sports Medicine 2021;51:1935-1945 · Bahr, Thorborg, Ekstrand, BJSM 2015;49:1466-1471 · Harøy et al., BJSM 2019;53:150-157 · Harøy et al., Am J Sports Med 2017;45:3052-3059 · Harøy et al., Scand J Med Sci Sports 2019;29:1092-1100 · Stensø et al., BMJ Open 2022;12:e060611.
Heading and concussion: FFF, Jeu de tête: un livret clé en main, 16 December 2025 · FFF medical commission, La commotion cérébrale sur le terrain de football (undated) · ASF/SFV, Ausführungsbestimmungen Kinder- und Jugendfussball 2026/27 and the Kopfball module of the J+S/BASPO Manual Fussball · watson.ch, 1 February 2023 (Patrick Bruggmann, ASF, on the record) · Marx-Berger, SEMS-journal, 24 October 2022 · The FA, Heading in football (from 2024-25) and the 17 May 2024 announcement · Scottish FA, Heading Guidelines (undated) · US Soccer, Player Safety Campaign — heading guidelines (undated) · Patricios et al., BJSM 2023;57:695-711 (Amsterdam consensus) · FIFA, Concussion Protocol for Medical Staff, August 2024 · UEFA concussion charter, 29 November 2021 · IFAB, additional permanent concussion substitutions protocol, 138th AGM, 2 March 2024 · Mackay et al., NEJM 2019;381:1801-1808.
Load, growth, conditioning: Gabbett, BJSM 2016;50:273-280 · Impellizzeri et al., Int J Sports Physiol Perform 2020;15:907-913 and J Athl Train 2020;55:885-892 / 893-901 · Lolli et al., BJSM 2019;53(15):921-922 and 53(24):1510-1512 · Malina et al., Am J Hum Biol 2021;33:e23551 · Monasterio et al., Int J Sports Med 2023;44:292-297 · Pakarinen et al., Health Sci Rep 2025;8:e71096 · Malina et al., Sports Medicine 2019;49:1671-1685 · Jayanthi et al., Am J Sports Med 2015;43:794-801 · Lloyd, Faigenbaum, Stone et al., BJSM 2014;48:498-505 · BASPO / mobilesport.ch, Konditions-Circuittraining Fussball: Kraft (11/2012) · Zhang et al., BMC Sports Sci Med Rehabil 2026;18 · Trotta et al., Br Med Bull 2025;156 · Gonçalves et al., Res Q Exerc Sport 2026.
Epidemiology: Ekstrand et al., BJSM 2011;45:553-558 · Jones et al., Sports Medicine 2019;49:1879-1899 · van Beijsterveldt et al., Clin J Sport Med 2014;24:337-342 · UEFA Women's Elite Club Injury Study 2018/19-2021/22 (mirrored copy).
Corpus verified 1 August 2026; page dated 2 August 2026. Federation rules change — re-check your own every season.