Hamstring injury rates have increased and now constitute 24% of all injuries (UEFA study)

Key points

1. 01Hamstring injuries grew from 12% of all injuries in 2001/02 to 24% in 2021/22, and caused 20% of all injury absence days by the final season.
2. 02Training hamstring injury incidence rose 6.7% annually (95% CI 1.7% to 12.5%) and match injury incidence rose 3.9% annually (95% CI 0.1% to 7.9%) between 2014/15 and 2021/22.
3. 03Match play carries roughly 10 times the hamstring injury risk of training (4.99 vs 0.52 per 1000 hours; RR 9.67, 95% CI 8.93 to 10.47).
4. 0418% of all hamstring injuries were recurrences, and 69% of those recurrences happened within 2 months of return to play.
5. 05Biceps femoris was the most commonly injured muscle (80% of located injuries), and structural injuries (with MRI evidence of fibre tear) made up 71% of classified injuries.

How it was conducted

Design

Prospective cohort study (UEFA Elite Club Injury Study, ECIS), 21 consecutive seasons 2001/02 to 2021/22

Participants

3909 male professional football players from 54 teams across 20 European countries (323 team-seasons, 9728 player-seasons)

Exposure

2 131 561 total exposure hours (1 787 823 training hours and 343 738 match hours)

Primary outcome

Hamstring injury incidence (injuries per 1000 player hours) and burden (absence days per 1000 player hours)

Analysis

Poisson regression using generalised linear models; time-trend analyses for full 21-season period and sub-period 2014/15 to 2021/22

Injury classification

Munich muscle injury classification (structural vs functional) and location (biceps femoris vs semitendinosus/semimembranosus) recorded from 2011/12 onward

What they found

• 2636 hamstring injuries recorded over 21 seasons, representing 19% of all 14 057 registered injuries.
• Proportion of injuries classified as hamstring injuries increased from 12% in 2001/02 to 24% in 2021/22.
• Proportion of all injury absence days caused by hamstring injuries increased from 10% to 20% over the study period.
• Hamstring injury incidence was 10 times higher during match play than training (4.99 vs 0.52 per 1000 hours; RR 9.67, 95% CI 8.93 to 10.47).
• Median lay-off per hamstring injury was 13 days (IQR 7-22); structural injuries had a median of 17 days (IQR 11-25) versus 6 days (IQR 4-10) for functional injuries.
• Training hamstring injury incidence increased 6.7% annually (95% CI 1.7% to 12.5%, p=0.009) between 2014/15 and 2021/22.
• Training hamstring injury burden increased 9.0% annually (95% CI 1.2% to 18.3%, p=0.024) between 2014/15 and 2021/22.
• Match hamstring injury incidence increased 3.9% annually (95% CI 0.1% to 7.9%, p=0.045) between 2014/15 and 2021/22.
• Match hamstring injury burden increased 6.2% annually (95% CI -0.5% to 15.0%, p=0.116, not statistically significant) between 2014/15 and 2021/22.
• 475 injuries (18%) were recurrences; early recurrences (within 2 months) accounted for 325 of those (69%).
• Recurrences were 9 times more likely in matches than training (RR 9.25, 95% CI 7.67 to 11.15).
• 71% of classified injuries (n=1312 of 1795) were structural; 80% of location-classified injuries were biceps femoris (n=1054 of 1319).
• Running/sprinting was the mechanism in 62% of structural injuries and 51% of functional injuries.
• Almost 50% of match hamstring injuries occurred in the last 15 minutes of each half (p<0.001).

Limitations

• Participating team roster changed season by season (only UCL group-stage teams included), which may introduce selection effects and limit generalisability to lower-division clubs.
• Time-loss injury definition may miss injuries where players return despite persisting symptoms, potentially underestimating true burden.
• Causal factors driving the increase cannot be established from this observational design; hypotheses about training intensity and crowded calendars remain speculative.
• Classification of structural vs functional injuries changed with improvements in MRI technology, so part of the apparent rise in structural injuries may reflect better imaging rather than a true biological increase.

Why it matters

For patients

Players who have suffered a hamstring injury face roughly a 1-in-5 chance of re-injury, with the greatest risk in the first 2 months after returning to play, making this a critical window for careful rehabilitation and load management.

For clinicians

Hamstring injuries now account for nearly 1 in 4 injuries and 1 in 5 absence days in elite football, and rates are still climbing despite prevention programmes, signalling an urgent need for better implementation of evidence-based strategies and closer monitoring during the 8-week post-return period.

For readers

This 21-year dataset from the UEFA Elite Club Injury Study is the largest long-term surveillance of hamstring injuries in professional sport and provides benchmark incidence and burden data against which future interventions can be measured.