The power–duration relationship is a robust phenomenon that demarcates the upper
threshold of sustainable exercise and accurately predicts the onset of exhaustion when that
threshold is exceeded. The two foundational parts of this relationship, the critical power (CP)
and curvature constant (W′), relate to “aerobic” and “energy stores” factors in the body,
respectively. Crucially, the CP concept provides a rigorous framework for studying and
helping to understand the integrative physiology of exercise performance and the …