A4 Sports Injuries

Topic

In a sports context, tissue sustains an injury when the applied force—or the resulting deformation—exceeds the tissue's mechanical resistance, specifically its failure threshold. As long as the force and deformation remain below this threshold, the tissue absorbs them without damage; once the force or deformation crosses that threshold, injury occurs.

The force and deformation experienced by the tissue depend, first and foremost, on impact mechanics: the way the body collides, decelerates, or changes direction during a sports movement determines the magnitude of force and deformation ultimately transmitted to the tissue. The more abrupt or concentrated the impact, the greater the force the tissue must withstand within a shorter timeframe.

Alongside impact mechanics, the muscle's force-generating capacity also influences the force ultimately exerted on the tissue: when a muscle contracts intensely at the moment of impact, that muscular force combines with the external force, increasing the total load on the tissue and bringing it closer to the failure threshold.

In addition to impact mechanics and muscular force generation, the power dissipated by the tissue determines how much energy is converted into actual deformation: the less power the tissue dissipates during impact, the greater the proportion of energy converted into tissue deformation, thereby pushing it closer to the failure threshold.

The model integrates these three factors—impact mechanics, muscular force-generating capacity, and tissue power dissipation—to identify the injury mechanism: specifically, which of the three factors drove the force or deformation applied to the tissue beyond its failure threshold. An injury mechanism driven by impact mechanics requires a different corrective approach than one driven by excessive muscle contraction or the tissue's limited capacity to dissipate power. Identifying the mechanism of injury allows for the design of a return-to-sport progression—a sequence of increasing loads reapplied to the injured tissue, specifically tailored to the factor (impact mechanics, muscle force generation capacity, or dissipated power) that originally caused the force or deformation to exceed the tissue's failure threshold—until the tissue can once again tolerate those loads without approaching that threshold.

ID:513