Overuse Injury as a Result of Pathologically Altered Myofascial Force Transmission

Overuse injuries such as tendinopathy, iliotibial band (ITB) syndrome, plantar fasciitis make up between 30% to 90% of musculoskeletal disorders in sports. Overuse injuries are commonly suggested as a result of repetitive microdamage in the affected tissue that causes pain. Manual therapy for overuse injuries usually focuses on the area of symptom; however, such approach may not address the real cause.

A review by Jan Wilke and colleagues published in Exercise and Sport Sciences Review hypothesize that the development of some sports-related soft tissue injuries can be caused by pathologically altered force transmission from anatomically connected myofascial structures.

Fascia and connective tissues envelope muscles, and the entire skeletal muscle fuses morphologically with the surrounding structures. The muscle is also intimately connected to its deep fascia. This construction enables the muscle to selectively stiffen and create and maintain tension in the fascia. There is also observed myofascial continuity, where skeletal muscles are directly connected, forming a ubiquitous body-wide network linked by connective tissues.

Intermuscular connectivity does not merely provide stabilization and cohesion. A common feature of all linking tissues (tendons, deep fasciae, and ligaments) is that they display high tensile strength. As a consequence, substantial amounts of force can be transmitted between the skeletal muscles via fascial tissue continuity. As long as the tissue connection between two muscles can be made stiff enough, altered local forces could affect a structure connected in series. Skeletal muscles are linked to each other, not only structurally but also mechanically.

In several sports-related overuse injuries, nonlocal abnormalities, such as increased stiffness or hypertonicity, can manifest in morphologically connected body regions. Local changes of the mechanical properties may be significant enough to stiffen and excessively preload the tissue continuity to an adjacent muscle. Over time, the load transmitted via the myofascial pathway causes a stiffening of the tissues in the structurally connected region. Particularly, if this region already had a heightened stiffness, a combination of transmitted and local strains could lead to pain and dysfunction. Local dysfunctions could radiate mechanically to neighbouring structures.

The authors concluded that myofascial force transmission could play a role in the development of overuse injuries in sport. In a range of pathologies such as plantar fasciitis, LBP, groin pain, ITB syndrome, and chronic shoulder pain, nonlocal abnormalities (e.g., altered mechanical tissue properties) distant to the area of symptom localization can be observed.

There are evidences that nonlocal exercise can affect structures distant to the site of the affected area. For example, stretching of the calf and the dorsal thigh increases the range of motion of cervical area, and self-massage of the plantar tissues of the foot increases the flexibility of hamstring. It is still debatable if these nonlocal effects on flexibility are due to myofascial force transmission or central nervous system adaptation. However, both mechanisms can act together. There is a lack of research examining the effectiveness of remote exercise in the treatment of overuse injuries.