  Massive stars undergo fundamental-mode and first-overtone radial pulsations
with periods of 100-1000 days as Red Supergiants (RSGs). At large amplitudes,
these pulsations substantially modify the outer envelope's density structure
encountered by the outgoing shock wave from the eventual core collapse of these
$M>9M_\odot$ stars. Using Modules for Experiments in Stellar Astrophysics
(MESA), we model the effects of fundamental-mode and first-overtone pulsations
in the RSG envelopes, and the resulting Type IIP supernovae (SNe) using
MESA+STELLA. We find that, in the case of fundamental mode pulsations, SN
plateau observables such as the luminosity at day 50, $L_{50}$, time-integrated
shock energy $ET$, and plateau duration $t_{\rm p}$ are consistent with radial
scalings derived considering explosions of non-pulsating stars. Namely, most of
the effect of the pulsation is consistent with the behavior expected for a star
of a different size at the time of explosion. However, in the case of overtone
pulsations, the Lagrangian displacement is not monotonic. Therefore, in such
cases, excessively bright or faint SN emission at different times reflects the
underdense or overdense structure of the emitting region near the SN
photosphere.
