Sprint-related hamstring injuries in professional football occur closer to individual maximal running speed: a matched video and tracking case–control study
This matched case–control study combining video and tracking data reveals that sprint-related hamstring injuries in professional football occur at higher absolute speeds and closer to a player's individual maximal running speed compared to non-injury sprints, with the risk of injury significantly increasing as the sprint speed approaches the player's seasonal maximum.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
In the high-stakes world of professional football, the hamstring muscle is a frequent victim of the sport's most demanding physical actions. These muscles, located at the back of the thigh, are essential for running, yet they are prone to tearing when the body is pushed to its limits. For decades, coaches and medical staff have known that these injuries often happen while a player is sprinting at high speed. To understand why, researchers have long relied on measuring how fast a player is moving in absolute terms, such as kilometers per hour. However, a single speed number tells only part of the story. For one athlete, running at a certain pace might feel like a casual jog, while for another, that same speed could represent a near-maximal effort that pushes their body to the edge of its capacity. This difference in individual ability suggests that the risk of injury might depend less on the raw speedometer reading and more on how hard that speed feels to the specific player running it.
A new study set out to investigate this precise question by looking closely at the moments when professional players actually got hurt. The researchers gathered data from forty separate hamstring injuries that occurred during official matches in Spain's top football league. To understand what made these specific sprints dangerous, they did not just look at the injury in isolation. Instead, they paired each injury event with two other sprints performed by the same player during the same match, where no injury occurred. This method allowed them to compare a dangerous run with a safe run, controlling for the unique physical traits and playing style of each individual. By combining video footage with precise optical tracking data that recorded the players' movements, the team could measure exactly how fast the players were going and how close that speed was to their personal maximums recorded earlier in the season.
The analysis revealed a clear pattern: the sprints that ended in injury were performed at slightly higher speeds than the safe sprints the same players completed during the same game. On average, the injury sprints reached a peak speed of 27.2 kilometers per hour, while the safe sprints averaged 26.0 kilometers per hour. More importantly, when the researchers looked at these speeds relative to what each player was capable of, the difference became even more significant. The injury sprints occurred when players were running at approximately 85 percent of their fastest recorded speed from earlier in the season, whereas the safe sprints happened at about 81 percent. This suggests that the closer a player runs to their personal top speed, the higher the likelihood that a hamstring injury will occur. The data showed that for every ten percentage points a player's speed increased relative to their personal maximum, the odds of that specific sprint resulting in an injury roughly doubled.
The study also examined the context of these injuries to see if other factors played a role. The vast majority of the injuries, about 95 percent, happened without any physical contact from another player. Most occurred when the player did not have possession of the ball, and they typically happened while the player's foot was in the air, a phase of running known as the open kinetic chain. These findings reinforce the idea that the injury is a result of the body's internal mechanics under extreme load rather than an external collision. However, the researchers were careful to note that running fast is not the sole cause of injury. In half of the cases, the player completed at least one sprint during the match that was faster than the one where they got hurt, yet they remained uninjured. This indicates that while high speed is a major risk factor, it is not a guaranteed trigger.
The results challenge the simple idea that there is a single "danger zone" speed, such as running faster than 90 percent of one's maximum, that should be avoided at all costs. The study found that while injuries were more common at these high intensities, they were not exclusive to them, and many players successfully completed sprints at similar or even higher intensities without harm. The researchers conclude that speed should be viewed as one piece of a larger puzzle that includes fatigue, muscle strength, and tactical demands. Rather than setting rigid speed limits to prevent injury, the findings suggest that monitoring how hard a player is working relative to their own personal capacity provides a more useful picture of risk. This approach helps coaches understand the intensity of a specific moment in a game, offering a clearer way to manage player workload without assuming that high speed alone is the enemy.
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