  The precision obtainable in phenomenological applications of Chiral
Perturbation Theory is currently limited by our lack of knowledge on the
low-energy constants (LECs). The assumption that the most important
contributions to the LECs come from the dynamics of the low-lying resonances,
often referred to as the resonance saturation hypothesis, has stimulated the
use of large-Nc resonance lagrangians in order to obtain explicit values for
the LECs. We study the validity of the resonance saturation assumption at the
next-to-leading order in the 1/Nc expansion within the framework of Resonance
Chiral Theory (RChT). We find that, by imposing QCD short-distance constraints,
the chiral couplings can be written in terms of the resonance masses and
couplings and do not depend explicitly on the coefficients of the chiral
operators in the Goldstone boson sector of RChT. As we argue, this is the
counterpart formulation of the resonance saturation statement in the context of
the resonance lagrangian. Going beyond leading order in the 1/Nc counting allow
us to keep full control of the renormalization scale dependence of the LEC
estimates.
