O2 Loss Minimization

Topic

The energy loss associated with this athletic movement is generally classified into both internal and external losses. Internal losses encompass viscous dissipation within the athlete's muscles and soft tissues, as well as the co-activation of agonist and antagonist muscles—a phenomenon modeled elsewhere in this framework—which generates negative work while the agonist muscle simultaneously performs positive work. Furthermore, internal losses include the work required to accelerate and decelerate the athlete's body segments, as well as tendon hysteresis—another aspect modeled separately—which represents a moderate energy loss during each tendon cycle. External losses, on the other hand, include aerodynamic drag (modeled here as proportional to the cube of the athlete's velocity, rather than the square as in other models within this framework), friction with the surface, and the work associated with the collision between the athlete's foot and the ground—a collision modeled elsewhere to account for the redirection of the center of mass during each foot-strike in running. Finally, the athlete's overall mechanical efficiency—defined as the ratio of useful work to metabolic energy consumed—is considerably lower in cycling (an inherently efficient cyclic movement) than in running, where the athlete benefits from significant elastic energy recovery, a factor also modeled separately within this framework. Therefore, given the internal and external losses with which this model began, the ultimate minimization of these losses is achieved by optimizing the athlete's cadence, posture, footwear, and final movement technique. The collision cost—which was a starting parameter of the model—constitutes the largest component of the internal losses incurred during the athlete's run; this same collision cost is also factored into another model within this framework as part of the total cost of the run. Consequently, if the athlete further optimizes the movement technique established at the start of the model, the final collision cost of the run is reduced even further.

ID:486