  We examine the influence of resonance decay dynamics on momentum spectra of
pions in heavy-ion collisions. Taking the decay $\omega \rightarrow 3 \pi$ as
an example, we demonstrate how details of the decay matrix element can modify
the physical observables. Such a dynamical effect is commonly neglected in
statistical models. To remedy the situation, we formulate a theoretical
framework for incorporating hadron dynamics into the analysis, which can be
straightforwardly extended to describe general N-body decays.
