Evidence first. Honest always.

How the rules are graded

Every rule in the app carries one of four labels. We only use wording like “linked with fewer injuries in studies”, because that’s what the research shows: an association in groups of players, not a promise for you.

Untested numbers, such as readiness cut-offs and dose steps, live in one place in the app’s coaching engine so they can be reviewed with real data after the first season.

What the evidence says

The FIFA 11+ warm-up

A meta-analysis of the FIFA 11+ found teams that used it had about 39% fewer injuries (injury rate ratio 0.61) in recreational and sub-elite players Thorborg et al. 2017. A trial in college players found similar results Silvers-Granelli et al. 2015, and an earlier trial of a comprehensive warm-up in young female players did too Soligard et al. 2008. Higher adherence went with fewer injuries in youth female players Steffen et al. 2013 Zarei et al. 2026. The programme was designed for at least twice a week, so that’s the app’s target. Our warm-up uses the same parts and dose as the official FIFA 11+; the study results belong to FIFA 11+, not to our version.

Nordic hamstring curls

Programmes that included the Nordic were linked with about half the hamstring injury rate in a meta-analysis of 8,459 athletes van Dyk et al. 2019, with trials in Danish and Dutch football Petersen et al. 2011 van der Horst et al. 2015. Low volume builds strength about as well as high volume Cuthbert et al. 2020 Lacome et al. 2020, but muscle-length gains reversed within two weeks of stopping Presland et al. 2018, so the app never lets a gap run past two weeks. One honest caveat: a 2026 network meta-analysis found the Nordic on its own gave a modest, uncertain benefit, with the FIFA 11+ the most consistent Hong et al. 2026. The app pairs both.

Copenhagen adductor work

In a trial in semi-professional men, reported groin problems were 41% lower with a Copenhagen adductor programme Harøy et al. 2019, and eight weeks of it raised adductor strength Ishøi et al. 2016. Pre-season is three times a week; in-season, once.

Ankles and knees

After a recent ankle sprain, a home balance programme was linked with fewer repeat sprains (22% against 33%) Hupperets et al. 2009. Programmes including balance and landing work were linked with fewer knee injuries in female players Waldén et al. 2012 Su et al. 2025, so female players get the knee-control parts of the warm-up at full dose every time.

Strength in season

In a small study of professionals, one strength session a week kept strength and sprint gains, while one every two weeks didn’t Rønnestad et al. 2011. Network meta-analyses rank strength training at or near the top for short sprints and jumps in footballers Wang et al. 2026 Du et al. 2026 Oliver et al. 2023. Strength can be kept with surprisingly little training if the effort stays high Spiering et al. 2021.

Recovery after a match

Strength, sprint and soreness can stay below normal for up to 72 hours after a match Nédélec et al. 2012 Ascensão et al. 2008 Doeven et al. 2018. That’s why heavy legs wait until two days after a game at the earliest.

Fitness and speed

Small-sided games matched interval running for aerobic fitness Moran et al. 2019, so club training counts. Repeated-sprint ability comes mostly from sprint and jump work Liu et al. 2024 Clemente et al. 2021. Most semi-pro sprints are short and many are curved Oliva-Lozano et al. 2023, so the drills are too. Change-of-direction blocks follow a recent meta-analysis Zhao et al. 2026.

Readiness and watch data

Countermovement jump height is a useful marker of neuromuscular fatigue Claudino et al. 2017, and short self-report questions track the training response at least as well as many objective measures Saw et al. 2016. HRV-guided training gave only small, mostly non-significant extra gains in endurance athletes Manresa-Rocamora et al. 2021 Düking et al. 2021, so watch data is one extra vote, never the decider.

No workload ratios

The acute:chronic workload ratio was widely used to forecast injuries, but its statistical problems are well documented Impellizzeri et al. 2020. The app describes your week as higher, stable or lower, and shows no ratios or risk numbers.

Head injury

The head injury feature follows The FA’s concussion guidelines The FA Concussion Guidelines 2023 and the UK grassroots guidance with its graduated return UK grassroots concussion guidelines 2024: full training not before day 15, matches not before day 21. It never says you’re fit to play. The app never programmes heading practice and shows The FA’s heading guidance as a card FA heading guidance 2021.

Players over 35

In a survey of amateur masters footballers, 22% reported possible heart symptoms and half said they would play on with chest pain Francis et al. 2022. The 35+ setting shows a clear card: stop playing and call 999.

Young players

Youth strength training follows the international consensus: technique and movement skill first, then load Lloyd et al. 2014. Weekly organised hours stay at or under the player’s age in years, because in a study of 7 to 18 year olds, more hours than age went with more serious overuse injuries Jayanthi et al. 2015.

Where the evidence runs out

A lot of S&C for amateur football has never been trialled. There’s no English grassroots GPS data, so targets come from your own tests, not pro numbers Mohr et al. 2003. The day-before and day-after rules and the double-header handling are coaching convention drawn from elite data. Where that’s the case, the app says so and stays conservative. We don’t predict injuries, label anyone, or promise that any exercise stops injuries or concussion.

All references

Every entry links to its DOI, PubMed record or official page. Titles aren’t reproduced; each entry describes what the paper looked at.

1. Ascensão A et al. 2008. Clin Biochem. Muscle damage and recovery markers after a football match. DOI
2. Ayala F et al. 2017. PLoS One. Acute effects of three warm-up protocols, including the FIFA 11+, on sprint and jump performance in amateur players. DOI
3. Bradley PS et al. 2009. J Sports Sci. High-intensity running by position in English Premier League matches. DOI
4. Buchheit M et al. 2023. Biol Sport. Exposure to near-maximal sprinting two days before a match and hamstring injuries in elite teams (observational). DOI
5. Claudino JG et al. 2017. J Sci Med Sport. Meta-analysis of the countermovement jump for monitoring neuromuscular status. DOI
6. Clemente FM et al. 2021. Int J Environ Res Public Health. Review of small-sided games and repeated-sprint ability. DOI
7. Cumberland FA. Playing football during June (the closed season for 11-a-side), 2023. Source
8. Cuthbert M et al. 2020. Sports Med. Review of Nordic hamstring training volume and strength and fascicle-length changes. DOI
9. Di Salvo V et al. 2007. Int J Sports Med. Positional match demands in elite football. DOI
10. Di Salvo V et al. 2008. J Sports Med Phys Fitness. Match activity of elite goalkeepers. PubMed
11. Doeven SH et al. 2018. BMJ Open Sport Exerc Med. Review of recovery time after a football match. DOI
12. Du et al. 2026. Front Physiol. Network meta-analysis of training methods for footballers’ sprint and jump performance. DOI
13. Düking P et al. 2021. J Sci Med Sport. HRV-guided training and individual responses. DOI
14. Ekstrand J et al. 2011. Am J Sports Med. Injury patterns in professional football (UEFA injury study). DOI
15. The Football Association. Adult amateur heading guidance, July 2021 (at most one session a week with heading practice, up to 10 headers in that session). Source
16. FIFA Medical Network. The FIFA 11+ warm-up programme: 15 exercises in three parts, about 20 minutes, three levels per exercise. Official, free. Source
17. Fragala MS et al. 2019. J Strength Cond Res. NSCA position statement on resistance training for older adults. DOI
18. Francis et al. 2022. Intern Med J. Heart symptoms and attitudes to chest pain in amateur masters footballers. DOI
19. Green B et al. 2020. Br J Sports Med. Meta-analysis of factors linked with hamstring strain injury in sport. DOI
20. Harøy J et al. 2019. Br J Sports Med. Cluster randomised trial of the Copenhagen adductor programme in Norwegian semi-professional men’s football. DOI
21. Hong et al. 2026. Sports Med Open. Network meta-analysis of exercise programmes and hamstring injuries in football. DOI
22. Hupperets MDW et al. 2009. BMJ. Randomised trial of a home balance programme after an ankle sprain. DOI
23. Impellizzeri FM et al. 2020. Int J Sports Physiol Perform. Problems with the acute:chronic workload ratio. DOI
24. Ishøi L et al. 2016. Scand J Med Sci Sports. Eight weeks of Copenhagen adduction training and eccentric hip adduction strength in footballers. DOI
25. Jayanthi NA et al. 2015. Am J Sports Med. Sports specialisation, weekly hours and overuse injuries in young athletes. DOI
26. Kaldaras et al. 2024. Appl Sci 14:7036. Positional running demands in amateur (Greek fourth division) football. DOI
27. Lacome M et al. 2020. Int J Sports Physiol Perform. Low- versus high-volume Nordic training in elite youth footballers. DOI
28. Liu et al. 2024. J Sports Sci Med. Meta-analysis of training methods and repeated-sprint ability in footballers. DOI
29. Lloyd RS et al. 2014. Br J Sports Med. International consensus position statement on youth resistance training. PubMed
30. Malone S et al. 2017. J Sci Med Sport. High-speed running exposure and injuries in Gaelic football (observational). DOI
31. Malone S et al. 2019. J Sci Med Sport. Maximal-velocity exposure and injuries in Gaelic football and hurling (observational). DOI
32. Manresa-Rocamora A et al. 2021. Int J Environ Res Public Health. Meta-analysis of HRV-guided training in endurance athletes. DOI
33. Marshall PW et al. 2015. J Strength Cond Res. Acute effect of one set of Nordics on eccentric hamstring strength in amateur players. DOI
34. McNulty KL et al. 2020. Sports Med. Meta-analysis of menstrual cycle phase and exercise performance. DOI
35. Mohr M et al. 2003. J Sports Sci. Match performance of top-class and moderate professional footballers. DOI
36. Moran J et al. 2019. Sports Med. Meta-analysis of small-sided games versus running-based training for aerobic fitness. DOI
37. Nédélec M et al. 2012. Sports Med. Review of recovery after a football match. DOI
38. Oliva-Lozano JM et al. 2023. J Hum Kinet. Sprint distances and curved sprints in semi-professional football. DOI
39. Oliver JL et al. 2023. Sports Med. Review of training methods and sprint performance in youth and adult footballers. DOI
40. Paton BM et al. 2023. Br J Sports Med. International consensus on return to play after hamstring injury. DOI
41. Petersen J et al. 2011. Am J Sports Med. Randomised trial of eccentric (Nordic) hamstring training in Danish men’s football. DOI
42. Presland JD et al. 2018. Scand J Med Sci Sports. Nordic training volume, then detraining, in recreationally active men. DOI
43. Rømer T et al. 2024. Scand J Med Sci Sports. Eight-week pre-season and aerobic fitness in sub-elite footballers. DOI
44. Rønnestad BR et al. 2011. J Strength Cond Res. One versus one-every-two-weeks in-season strength sessions in professional footballers (small sample). DOI
45. Saw AE et al. 2016. Br J Sports Med. Systematic review of self-reported versus objective measures for monitoring athletes. DOI
46. Silvers-Granelli H et al. 2015. Am J Sports Med. Cluster trial of the FIFA 11+ in male college football players. DOI
47. Soligard T et al. 2008. BMJ. Cluster randomised trial of a comprehensive warm-up in young female footballers. DOI
48. Spiering BA et al. 2021. J Strength Cond Res. The minimum training dose to keep strength and endurance. DOI
49. Steffen K et al. 2013. Br J Sports Med. Warm-up adherence and injuries in youth female football. DOI
50. Su et al. 2025. J Orthop Surg Res. Review of programmes and ACL injuries in female athletes. DOI
51. The Football Association. Concussion Guidelines, updated August 2023. For grassroots clubs without a trained healthcare professional, they point to the UK grassroots guidelines. Source
52. Thorborg K et al. 2017. Br J Sports Med. Meta-analysis of the FIFA 11+ in football players (injury rate ratio 0.61 in recreational and sub-elite players). DOI
53. Sport and Recreation Alliance and UK Government. Concussion Guidelines for Non-Elite (Grassroots) Sport, including the Graduated Return to Activity and Sport (GRAS). Updated November 2024. Source
54. van Beijsterveldt AM et al. 2014. Clin J Sport Med. Injuries in Dutch adult amateur football. DOI
55. van der Horst N et al. 2015. Am J Sports Med. Randomised trial of the Nordic hamstring exercise in Dutch amateur football. DOI
56. van Dyk N et al. 2019. Br J Sports Med. Meta-analysis of 8,459 athletes: programmes including the Nordic hamstring exercise and hamstring injury rates. DOI
57. Waldén M et al. 2012. BMJ. Cluster randomised trial of neuromuscular training and ACL injuries in adolescent female football. PubMed
58. Wang et al. 2026. J Sports Sci Med. Network meta-analysis of training methods for sprint and jump performance in footballers. DOI
59. Weir A et al. 2015. Br J Sports Med. Doha agreement on terms for groin pain in athletes. DOI
60. White A et al. 2020. J Sports Sci. Training and match demands of Premier League goalkeepers. DOI
61. Zarei M et al. 2026. Am J Sports Med. Adherence to the FIFA 11+ and injury outcomes. DOI
62. Zhao et al. 2026. J Sports Sci Med. Meta-analysis of change-of-direction training in footballers. DOI