Hamstring Strain Injuries
Hamstring strain injuries (HSIs) are a persistent and growing crisis in professional football (soccer). Rates have increased over the last two decades, escalating from 12% of all injuries in 2001/2002 to 24% in the 2021/2022 English football season (Ekstrand et al., 2023). Given that maximal velocity sprinting is the primary mechanism for these injuries, researchers and practitioners have long debated the role of biomechanics in injury prevention and rehabilitation.
Traditional methods for assessing sprint mechanics, such as 3-dimensional motion capture, are often considered the gold standard but are costly, time-consuming, and impractical for use in real-world team-sport environments, limiting their utility for large-scale athlete screening. To bridge this gap, a new screening tool has been developed: the Sprint Mechanics Assessment Score (S-MAS)(Bramah et al., 2024).
The S-MAS is a novel, 12-item qualitative movement screening tool designed for the in-field assessment of sprint running mechanics associated with HSIs. It utilizes slow-motion video footage to evaluate movement patterns across the gait cycle. Players are scored one point for the presence of specific suboptimal kinematic features (such as excessive thigh separation in touch down, or the foot contact in relation to the runner’s CoM, among others), yielding a total score from 0 (optimal mechanics) to 12 (suboptimal). The S-MAS has been shown to a reliable tool in a study examining 136 elite soccer players (men and women) and can be consistently integrated into practice to evaluate sprint kinematics(Bramah et al., 2024).
The composite nature of the S-MAS is crucial because it aims to reflect the collective contribution of multiple biomechanical parameters on potential HSI risk, shifting focus away from singular variables that may be insufficient to explain injury development.
Sprint Mechanics are Associated with Future Injury
Following the reliability testing, a six-month prospective cohort study involving 126 professional male footballers across the English football league investigated the direct association between S-MAS scores and the development of new sprint-related HSIs(Bramah et al., 2025).
This research was the first to identify an association between sprint running kinematics, assessed using the S-MAS, and prospective sprint-related HSI in elite male footballers. The results confirmed that higher S-MAS values were significantly greater among players with both a previous HSI and those who sustained a new sprint-related HSI during the follow-up period compared to uninjured players.
Crucially, when adjusting for confounders like age and previous injury, the findings showed a significant relationship between movement quality and future injury risk:
- For every one-point increase in a player’s S-MAS score, there was a 33% increase in the risk of developing a new sprint-related HSI over the six-month follow-up period.
- The study identified an S-MAS score of 5.5 or above as the optimal cut-off for identifying players with ‘suboptimal’ mechanics.
Clinical Takeaways
These findings underscore the importance of evaluating sprint mechanics within clinical practice. Given the S-MAS’s quick and practical nature, it can be integrated into regular in-season screening, injury prevention, and rehabilitation protocols. The study also noted that players with a previous HSI tended to have higher S-MAS scores, suggesting that suboptimal sprint mechanics may often be inadequately addressed during rehabilitation.
It is vital to remember that injury development is multifactorial. While sprint running mechanics influence the mechanical strain applied to the hamstrings, factors like eccentric hamstring strength and muscle architecture also influence the muscle’s capacity to tolerate that strain. Therefore, the S-MAS should be used holistically, complementing other injury risk assessments.
The Lab Application
Seeing the importance of these assessment tools, we have implemented this into our pre-and mid-season testing. This appears to be a helpful and easy to highlight at risk athletes. We’ve used this pre-season testing to investigate things like single leg jumps in ACLR athletes ( read more about that here)In collaboration with our strength and conditioning coaches we have begun to implement correctives and tissue loading to help correct form. We have also examined the relationship between S-MAS score and its correlation with spring speed. Interestingly, our regression models have shown that there is no correlation between spring speed and S-MAS (using S-MAS as a proxy for spring biomechanical quality). This tell us that the Interestingly, our regression models have shown that there is no correlation between spring speed and S-MAS (using S-MAS as a proxy for spring biomechanical quality). This tell us that perhaps it serves a strong purpose in injury reduction and other variables may be more significant to improve performance.
About The Author:
Maciek Krolikowski,
Physiotherapist, MScPT, MSc, BScKin
Maciek is a performance physiotherapist at The Lab Rehab and Performance. He completed his MScPT at the UofA, MSc in Biostatistics and Epidemiology. He is a CIS/USports nationally ranked sprinter with the University of Calgary Dinos. His special interests are running-related injuries, rehabilitation, and injury prevention. If you have any questions, comments, or concerns feel free to email us at: info@thelabrehabandperformance.
Or book an appointment directly with Maciek HERE
References
Bramah, C., Rhodes, S., Clarke-Cornwell, A., & Dos’santos, T. (2025). Sprint running mechanics are associated with hamstring strain injury: a 6-month prospective cohort study of 126 elite male footballers. British Journal of Sports Medicine. https://doi.org/10.1136/bjsports-2024-108600
Bramah, C., Tawiah-Dodoo, J., Rhodes, S., Elliott, J. D., & Dos’Santos, T. (2024). The Sprint Mechanics Assessment Score: A Qualitative Screening Tool for the In-field Assessment of Sprint Running Mechanics. American Journal of Sports Medicine, 52(6), 1608–1616. https://doi.org/10.1177/03635465241235525
Ekstrand, J., Bengtsson, H., Waldén, M., Davison, M., Khan, K. M., & Hägglund, M. (2023). 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 from 2001/02 to 2021/22. British Journal of Sports Medicine, 57(5), 292–298. https://doi.org/10.1136/bjsports-2021-105407