To clarify these aspects I suggest two papers to read:
Optimizing the "priming" effect: influence of prior exercise intensity and recovery duration on O2 uptake kinetics and severe-intensity exercise tolerance.
J Appl Physiol (1985). 2009 Dec;107(6):1743-56.
Effects of priming exercise on VO2 kinetics and the power-duration relationship.
Med Sci Sports Exerc. 2011 Nov;43(11):2171-9.