One of the greatest threats for a team of athletes is the risk of muscle injury during the season. As a direct result, one of the fundamental challenges facing sports medicine is how to improve the prevention, diagnosis and recovery process for muscle injuries.

Despite its importance, there is still no objective, globally-accepted classification for determining the prognosis of a muscle injury. A few years ago, FC Barcelona, together with Duke Sports Science Institute in the United States and the Aspetar hospital in Qatar, proposed a model that the club is currently using —published in Sports Medicine magazine—which includes four essential points: the injury mechanism, the location, the degree of damage, and whether it is a relapse. An article published in The Orthopaedic Journal of Sports Medicine —in which physicians Ricard Pruna and Gil Rodas, members of the club’s medical services, participated— now suggests taking this a step further by considering the detailed structure of the area affected, and treating the extracellular matrix as an essential player in the prognosis of the injury.

A detailed analysis

All muscle groups contain a population of cells or muscle fibers which carry out the contraction. But they also have and need a connective tissue which forms part of the extracellular matrix.  The muscle fibers constantly interact with the matrix, more specifically with the endomysium, perimysium and epimysium which surround the different cell populations and allow the muscle to contract and stretch.

“What we are proposing,” says Dr. Gil Rodas, a specialist physician at FC Barcelona, “is that the significance of an injury does not depend on the location itself, whether it is more proximal or more distal, but rather on the type of tissue affected and the amount of connective tissue damaged.”

Indirectly, the classification proposed by the club already included this concept within the location and degree of the injury, and especially by considering whether or not the aponeurosis (the most external membranes surrounding the muscles) or intramuscular tendons were affected. However, it is now proposed to go a step further by considering the extracellular matrix in detail.

The most serious injuries (and also the most frequent) occur in the muscle-tendon junction. However, there are actually two different structures in this area: the myotendinous junction itself, and the myofascial unit, which is adjacent to and integrated with the myotendinous junction and has less matrix. Injuries therefore have different prognoses depending on the structure affected. “We can barely differentiate them with ultrasounds, but magnetic resonance does allow us to see that level of detail,” states Rodas.

Overall, muscle injuries tend to be divided into myotendinous, myofascial and intramuscular injuries. However, it is very important to determine whether the “tendinous” part is affected, which we could call intratendinous injuries, both of the aponeurosis itself and the tendon.

These types of injuries tend to coexist, as it is a very common football injury, which affects the central tendon of the anterior rectus muscle as well as the proximal myotendinous junction.

In general, the more connective tissue affected in a muscle injury, the worse the prognosis. On the other hand, the less “tendinous” damage, the less matrix is affected, and the better the prognosis. This would be an example of myofascial injury.

This is why Dr. Ricard Pruna highlights that each type of injury must be well differentiated. Two injuries in the same muscle —either at the proximal, medial, or distal level— which look the same and are treated similarly, may progress in very different ways, depending on how the extracellular matrix has been affected. Thus, they must be managed and treated individually, as the recovery may differ by several weeks. “At FC Barcelona, we are among the first clubs to incorporate this approach,” shares Pruna and Rodas, who emphasize that “a good diagnosis is the mail factor for determining the prognosis.”

The Barça Innovation Hub team