Do niggles matter? Increased injury risk following physical complaints in football (soccer)

Key points

1. 01Minor non-time-loss complaints raised the relative risk of a time-loss injury within 7 days by 3.3 to 6.9 times compared to reporting no complaints
2. 02Good injury prediction was observed across all complaint categories, with area under the curve values of 0.73 to 0.83
3. 0328% of players on average reported a physical complaint each week that still allowed full or reduced training participation
4. 0468% of all time-loss injuries were preceded by a non-time-loss report at the same body location, rising to 94% for knee and 90% for hamstring injuries
5. 05The OSTRC self-report questionnaire captured 2.3 times more total physical complaints than the standard third-party Football Consensus method

How it was conducted

Design

Prospective cohort injury surveillance study over a full 35-week season (2016)

Participants

218 semi-professional male football players from 25 teams across 10 clubs (NSW National Premier League and Illawarra Premier League, Australia)

Injury surveillance

Weekly OSTRC Questionnaire on Health Problems (self-report) combined with third-party Football Consensus time-loss recording by Primary Data Collectors

Primary outcome

Relative risk of a time-loss injury within 7 days of a self-reported non-time-loss complaint

Statistical analysis

Generalised estimating equations with binary logistic regression; ROC curve analysis for predictive power (AUC)

What they found

• The baseline risk of a time-loss injury within 7 days with no health problems was 6% (entire cohort) and 9% (sub-group)
• Full participation with health problems (minor): RR 3.3 (95% CI 2.0 to 5.8), AUC 0.75 (CI 0.70 to 0.80), positive predictive value 22.0%
• Reduced participation due to health problems (moderate): RR 6.5 (95% CI 3.7 to 8.9), AUC 0.79 (CI 0.74 to 0.84), positive predictive value 34.5%
• Performance affected to a minor extent: RR 4.0 (95% CI 1.9 to 9.3); to a moderate extent: RR 5.5 (95% CI 3.2 to 9.4)
• Training volume affected to a minor extent: RR 4.4 (95% CI 1.9 to 5.7); to a moderate extent: RR 6.9 (95% CI 3.2 to 10.1)
• Ankle complaints: RR 6.8 (95% CI 0.1 to 376.0); lower leg complaints: RR 6.3 (95% CI 0.1 to 375.8)
• Hip/groin complaints: RR 3.5 (95% CI 2.4 to 5.2); hamstring: RR 4.7 (95% CI 2.0 to 11.0); knee: RR 3.6 (95% CI 2.0 to 6.1)
• Mean weekly injury prevalence (sub-group, TL and non-TL combined): 33% (95% CI 31.4% to 34.6%); non-TL injuries alone: 28% (95% CI 26.4% to 29.6%)
• Combining both surveillance methods: 49% (95% CI 47.0% to 51.0%) of players were affected by an injury each week
• Self-report captured 13.2 times more non-TL injuries than third-party recording (516 vs 39), while third-party recorded 2.6 times more TL injuries (226 vs 88)

Limitations

• Overall questionnaire compliance was low at 45%, with only 33% of players completing more than 80% of weekly surveys, which may limit generalisability
• Low specificity means many players flagged as at risk would not go on to sustain a time-loss injury, so the tool should not be used in isolation for injury prediction
• Multiple body locations could be recorded per survey week, making it impossible to confirm whether a subsequent time-loss injury was always a direct progression of the preceding complaint at the same site
• Results were obtained in a semi-professional setting; translation to professional football, where monitoring and medical access differ substantially, requires further study

Why it matters

For patients

Football players with nagging complaints, even those that do not stop them training, should report them promptly as they signal a meaningfully higher chance of a more serious injury within the next week.

For clinicians

Routine weekly self-report screening such as the OSTRC questionnaire can flag semi-professional players at elevated injury risk before a time-loss injury occurs, supporting early secondary prevention conversations and load adjustments.

For readers

This study strengthens the case for including non-time-loss complaints in injury surveillance systems, showing that standard Football Consensus methods alone substantially undercount the true injury burden in semi-professional football.