Hamstring injuries: settled prevention, unsettled return to play

If one injury defines the modern professional football calendar, it is the hamstring strain. In the UEFA Elite Club Injury Study, the share of all injuries diagnosed as hamstring injuries doubled from 12% in 2001/02 to 24% in 2021/22, and their share of total absence days rose from 10% to 20%. In the run-up to the 2026 World Cup, two pieces of work framed the problem from both ends: an April review on prevention in Aspetar's sports medicine journal, and a May survey of how elite European clubs decide when a player is ready to come back.

Read together, they show a familiar gap. Prevention is reasonably well defined. Return to play still varies widely from one club to the next.

Prevention: what is reasonably settled

The Aspetar review by Timmins and Bahr summarises the evidence a staff can act on:

• Previous injury is the strongest risk factor: roughly seven times the risk of a player with no history, with up to 13% of players suffering a new hamstring injury in a single season.
• Older age, short biceps femoris long-head fascicles and weak eccentric knee flexors are also associated with higher risk.
• Programmes that include the Nordic hamstring exercise roughly halve hamstring injury rates, based on a meta-analysis of 8,459 athletes. The effect depends on dose and adherence.
• Controlled sprint training lengthens biceps femoris fascicles, so combining eccentric work with regular high-speed exposure targets several risk factors at once.
• Rapid spikes in high-speed running have been proposed as a risk factor, although no numeric threshold has been established.
• Evidence for stretching as a preventive measure is weak and mixed.

One finding in the review has nothing to do with muscles. Medical staff from 15 Champions League clubs rated poor communication between staff members as a significant risk factor. A 2023 UEFA analysis of 14 elite teams also found that changes in head staff were associated with a higher hamstring injury burden that season, significantly so when the fitness coach or team doctor changed.

Return to play: no shared rulebook

The May 2026 study by Perna, Kerin, Lempainen and Beato, published in Research in Sports Medicine, asked practitioners at clubs in the Bundesliga, La Liga, Ligue 1, the Premier League and Serie A to rate return-to-play criteria across three phases: return to high-speed running, return to training and return to performance. Twenty-five practitioners completed the survey, working through two clinical cases.

The candidate criteria covered almost everything a modern department can measure: time since injury, absence of pain, flexibility, the Askling H-test, MRI, psychological readiness, isometric and eccentric strength (including a Nordic test), isokinetic testing, single-leg bridge, jump tests, completion of progressive on-field load, maximal sprint speed, repeated sprint ability and GPS metrics equivalent to match demands. Practitioners used a wide variety of criteria at each stage, and they wanted more, and more specific, tests for intramuscular tendon injuries than for myotendinous junction injuries. The authors conclude that the decision needs a multidisciplinary approach.

That echoes an earlier worldwide survey of 131 premier-league teams by Dunlop and colleagues: 95% used a continuum combining clinical, functional and psychological criteria, but the specific metrics and thresholds were unclear.

A return date is an estimate. A record of criteria passed is evidence.

Making criteria operational

The survey is small and describes practice rather than outcomes, so it cannot tell you which criteria work best. It does suggest a few habits that make any chosen set more useful:

• Agree the criteria for each phase before the injury happens, so the decision is not rebuilt under pressure on a Friday.
• Keep pre-injury reference values: eccentric strength, maximal speed, typical match high-speed distance. A criterion without a baseline is just a number.
• Make the progression visible to physio, S&C and the head coach at the same time, since communication gaps are themselves a risk factor.
• Keep eccentric and sprint work in the programme after return, because the previously injured player is the highest-risk player in the squad.

The Aspetar review also cites a coach-controlled ten-step return-to-play programme in Swedish amateur football that cut lower-limb reinjury risk by 75%. Structure, it seems, helps even when the resources are modest.

SquadStats records injuries through return-to-play phases 1 to 5, with direct physio and player messaging, and keeps fitness tests and imported GPS data (any brand, normalised into 23 metrics) on the same player profile, so pre-injury references are there when the criteria are checked.

Sources

1. Timmins R, Bahr R. Preventing the #1 football injury. Aspetar Sports Medicine Journal, 2026
2. Perna P, Kerin F, Lempainen L, Beato M. Return-to-play criteria for hamstring injuries in elite European football: a survey of current practice. Research in Sports Medicine, 2026
3. Ekstrand J et al. Hamstring injury rates have increased during recent seasons and now constitute 24% of all injuries in men's professional football: the UEFA Elite Club Injury Study. British Journal of Sports Medicine, 2023
4. Ekstrand J et al. Changes in head staff members in male elite-level football teams are associated with increased hamstring injury burden for that season. BMJ Open Sport & Exercise Medicine, 2023
5. Dunlop G et al. Return-to-play practices following hamstring injury: a worldwide survey of 131 premier league football teams. Sports Medicine, 2020