  Inertial effects in fluctuations of the work to sustain a system in a
nonequilibrium steady state are discussed for a dragged massive Brownian
particle model using a path integral approach. We calculate the work
distribution function in the laboratory and comoving frames and prove the
asymptotic fluctuation theorem for these works for any initial condition.
Important and observable differences between the work fluctuations in the two
frames appear for finite times and are discussed concretely for a
nonequilibrium steady state initial condition. We also show that for finite
times a time oscillatory behavior appears in the work distribution function for
masses larger than a nonzero critical value.
