CROSSING THE THRESHOLD

The critical power (CP) concept provides a mathematical and physiological framework to study exercise performance and fatigue development during high-intensity exercise. The model defines the hyperbolic relationship between power output and time to exhaustion by two parameters. The first parameter, CP itself, represent a metabolic rate that corresponds to the so-called maximal metabolic steady state (MMSS) intensity. This ¿critical¿ intensity is of significant importance for endurance athletes as it separates, as the name suggests, exercise intensities for which a metabolic steady state is possible or not. The second parameter, W', represents a finite amount of energy that can be spent above CP. In other words, whereas exercise below CP can be sustained for prolonged periods of time without fatigue, crossing this threshold will severely impair exercise tolerance due to the depletion of W'.