Mechanics More Important Than Metabolic Power in Sprinting
As the 2012 Olympic Games proceed in London, the track and field events are soon to be underway. Among the events are those that require sprinting. According to a new study, running mechanics, not conserving energy, is the key to optimal performance amongst elite sprinters.
This new study disproves the view that conserving energy maximizes performance in a sprinting event. The study was conducted by biomechanics researchers Matthew W. Bundle, at the University of Montana, and Peter G. Weyland, at Southern Methodist University in Dallas. The study demonstrated that energy conservation is not an important factor for performance in events lasting sixty seconds or less, but rather the opposite may be true.1
The authors of the study assessed neuromuscular activation using a diagnostic procedure known as electromyography. This procedure was used to measure electrical activity in the activated muscle fibers. This assessment showed neuromuscular activation increases continuously during all-out sprinting or cycling and running trials. The briefest trials that required the greatest forces, or explosiveness, displayed more rapid increases. This suggests that all-out sprinting is highly dependent on duration due to the speed of musculoskeletal fatigue during dynamic exercise requiring large force outputs.2
The study showed the key to optimal sprinting is to maximize the force at which the foot hits the ground. By doing so, this allows sprinters to translate musculosketal and ground reaction forces into motion. “Saving energy is critically important for endurance, but not for sprinting, which our findings indicate is not energy-limited,” Bundle said.3
Bundle and Weyland created a model to compare different modes of sprinting, primarily cycling and running. The subjects of the study included a wide range of sprint capabilities. “The predictive success of our force application model, both within and across modes of sprint exercise, indicates that as efforts extend from a few seconds to a few minutes, the fractional reliance on anaerobic metabolism progressively impairs whole-body musculoskeletal performance, and does so with a rapid and remarkably consistent time course,” the authors wrote. “In this respect, the sprint portion of the performance-duration curve predominantly represents, not a limit on the rates of energy re-supply, but the progressive impairment of skeletal muscle force production that results from a reliance on anaerobic metabolism to fuel intense, sequential contractions.”4
The researchers go on to say that since humans and other animals are similar in terms of metabolic and mechanical function, that the findings of this study likely apply to explosive performance capabilities of vertebrae animals in general.
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