The study everyone means
The most frequently cited trial is the work by Soligard and colleagues, published in the British Medical Journal in 2008. It built the reputation of structured warm-ups.
The design was unusually clean for sports research: a cluster randomised controlled trial with 125 Norwegian clubs and 1,892 female players aged 13 to 17, split into intervention and control groups. The intervention teams performed the programme now known as the FIFA 11+: eight minutes of running exercises, ten minutes of strength and balance, two minutes of running. The control teams warmed up as before.
What the study found, and what it did not
This is where a close look pays off, because it usually gets lost in the summary.
Clear and statistically supported were the reductions in severe injuries and in overuse injuries. Precisely the absences that take a player out of the squad for weeks.
On the overall figure the result was weaker than the usual citation suggests. Across all injuries the rate ratio was 0.71 — arithmetically 29 per cent fewer — with a 95 per cent confidence interval from 0.49 to 1.03. That interval includes 1. Which means: for the total number of all injuries, this single study did not reach the usual threshold for significance.
That is not an argument against prevention. It is an argument against relying on one study. The 30 to 50 per cent range comes from the combined picture across several trials and later reviews, not from this one number.
The factor that decides the effect
The practically most important finding came only from the follow-up analyses: the effect depends almost entirely on adherence.
Players with high programme adherence showed roughly a 35 per cent lower injury risk in the analyses. Teams that ran the programme only occasionally came nowhere near that. The literature treats about twice a week as the lower bound.
Three things follow from that, and they matter more in everyday coaching than any percentage.
The effect builds up. Depending on training frequency it takes around ten to twelve weeks before anything shows. Anyone who stops after four weeks because nothing happened never tested the programme.
The effect fades again. Prevention is not a course you complete but a habit you keep. After stopping, the risk returns towards the baseline.
Execution matters. The programmes work through neuromuscular control, not through the number of repetitions. A sloppy lunge trains nothing. What that looks like in practice is covered in integrating the 11+ and in core training.
What this means for your practice
- In the warm-up, not at the end. The programmes studied are warm-up programmes. At the end of a session execution suffers from fatigue.
- At least twice a week. Below that the evidence is thin and so is the effect.
- Ten to twelve weeks of patience. Judging it earlier is pointless.
- Watch and correct. Half the effect sits in the technique, not in getting through it.
- It costs nothing. No equipment, no licence, no expertise. The only price is ten to fifteen minutes of training time.
Where the evidence stays thin
Honesty belongs here, otherwise this article is just another presentation slide.
The original study looked at girls aged 13 to 17. Transferring that to boys, to adults and to children's football is plausible and supported by further work, but it is not the same as direct evidence. What makes sense with children is covered in injury prevention in youth football.
Adherence is hard to measure. Studies rely on coaches' self-reports. Someone who considers their programme consistent does not necessarily run it consistently.
Individual injury types are unevenly supported. For the hamstrings the evidence is particularly strong, for other areas weaker. Details in knee injuries and ankle injuries.
Conclusion
- The standard figure of "30 to 50 per cent" comes from the combined picture across several studies, not from one.
- The most-cited single trial (Soligard and colleagues, BMJ 2008) clearly showed fewer severe injuries and fewer overuse injuries. On the overall figure the confidence interval ran from 0.49 to 1.03 and therefore included 1.
- The most robust finding is not the percentage but the dependence on adherence: high adherence, roughly a third less risk.
- At least twice a week, in the warm-up, ten to twelve weeks of patience, and an eye on execution.