• football
• hamstrings
• injury prevention

Ekstrand et al recently showed that since 2001 hamstring injuries have increased by 4% annually in men’s professional football.1 A reason could be that evidence-based preventive measures are only partially implemented at the elite level,2 despite that they have been proven to be effective in the reduction of hamstring injuries in football in professional and amateur Danish footballers.3 However, while the rate of hamstring injuries increased during training sessions (4%/year), there was not a significant increase of these injuries during matches.1 The authors speculate that this may be due to the fact that the training sessions are more intense with the aim to better prepare the players to the match. They also hypothesise that this new training approach may be protective during matches and therefore the hamstring injury rate during match play has not changed1 despite that match intensity has increased in professional football.4 The authors conclude that the increasing injury rate is worrying, and prevention of hamstring injury should be given the highest priority.

Since the hamstring injury rate increased only during training, could we interpret these findings in another way? Would it be possible that the reason of this negative trend is already the result of a prevention strategy?

In their surveillance, Ekstrand et al are using a time loss definition of injury, as recommended by the consensus statement on injury definitions and data collection procedures in studies of football (soccer) injuries.5 This definition implies the recording of all injuries that force the players to stop for at least a part of a training session or a match.5 Therefore, if a player is continuing training or playing with a hamstring injury, there will be no record of this event. More recently, assessment of the epidemiology of overuse injury through new registration methods suggests that overuse injuries are under-reported in studies using a time loss definition of injury.6

Overuse injuries are caused by repetitive low-grade forces beyond the tolerance of the tissues and therefore their symptoms may increase gradually,7 with the players being able to continue football activity despite the presence of pain and reduced function. However, a continuous stress to the injured tissue may lead to further damage leading to the increasing symptoms and to the worsening of any anatomical damage. In the case of a hamstring injury, considering the type of performance required by football—high-speed running with sudden accelerations and decelerations, jumps and cutting movements—a progression of the lesion could quickly lead to a high-grade tear forcing the player to stop for several weeks. An important prevention strategy is then to educate players not to hide or ignore these symptoms and to inform the technical staff not to force the player to continue his activity without consulting the medical staff.

With the increasing knowledge in the field of football medicine, medical staff may possibly be much more cautious with these prodromal symptoms and aware of their possible consequences, also thanks to the development of radiological techniques. In fact, if MRI seems not to be useful in predicting time to return to sport after acute hamstring injuries,8 it can be of support for an early confirmation of the presence of a tissue abnormality and to justify an eventual exclusion of the player from the team as a preventive strategy. This precautionary approach may be effective for avoiding the progression to more serious hamstring lesions and may quickly allow the resolution of the symptoms without affecting the availability of the players during matches. It may therefore be possible that, as soon as some hamstring pain is appearing, the medical staff are cautiously removing the athlete from the training sessions for recovery, treatment and eventually individual sessions.

Perhaps this dark cloud of ever increasing hamstring training injury has a silver lining suggesting us that prevention strategies, like keeping at-risk players out of the training, are actually attempted and hopefully guiding us towards fairer skies of increased player availability.