The Curvature Constant Parameter of the Power-Duration Curve for Varied-Power Exercise

Abstract

We conclude that the work equivalent of W' is not affected by power variations during exhausting cycle ergometry, at least in the P range of 100-134% of CP.

Influence of blood flow occlusion on muscle oxygenation characteristics and the parameters of the power-duration relationship

“…The results of the present study lend credence to W= not being determined by a finite amount of work per se, but rather by other mechanisms such as the rate of attainment of "limiting" muscle metabolic perturbations (7,21,28,43,51), the magnitude of the severe domain (5,51), and/or the V O 2 slow component (40). Modeling the present data reveals that, while W= is utilized in its entirety for exercise intensities above CP, the proportion of W= that contributes directly to external work is not constant across this range of power outputs (Fig.…”

“…As such, CP represents the highest sustainable rate of aerobic ATP production for which W= will not be continuously utilized (4,12,38,39,42,51). The curvature constant in this model represents W=, modeled as a finite amount of work that can be performed above CP that, when fully expended, results in T lim (21,38,43,55). However, mounting evidence suggests that W= is not solely a finite amount of work, per se.…”

“…It is also evident that W= is a constant term that determines the limit of exercise tolerance (T lim ) for severe-intensity exercise (21, 55). Intramuscular energy stores (35,36,38), the accumulation of fatigue-inducing metabolites (7,18,21,28), and/or the magnitude of the severe-intensity domain (5, 51) have all been postulated to determine W=. Building evidence supports that complete utilization of W= is associated with consistent muscle phosphocreatine ([PCr]), inorganic phosphate ([P i ]), and hydrogen ion concentration ([H ϩ ]) perturbations, which may limit the amount of work performed above CP (28,43,51).…”

“…The growing body of evidence supports that CP represents the highest attainable steady state for aerobic energy production without continually drawing on W= and, as such, demarcates the boundary between the heavy-and severe-intensity exercise domains (4,12,38,39,42,51). It is also evident that W= is a constant term that determines the limit of exercise tolerance (T lim ) for severe-intensity exercise (21,55). Intramuscular energy stores (35,36,38), the accumulation of fatigue-inducing metabolites (7,18,21,28), and/or the magnitude of the severe-intensity domain (5,51) have all been postulated to determine W=.…”

High Agreement between Laboratory and Field Estimates of Critical Power in Cycling

“…In the hyperbolic relationship between power output and time to fatigue, CP represents the highest prolonged sustainable work rate, whilst the curvature constant (W') relates to a finite amount of energy which can be performed above CP [11,12,29]. Poole et al [30] characterized the physiological response to exercise performed at CP, showing that CP represents the highest power output at which and blood lactate stabilize.…”