  We investigate non-equilibrium properties of the frustrated Heisenberg
antiferromagnets on the triangular lattice. Nonequilibrium critical relaxation
of frustrated Heisenberg antiferromagnets shows a dynamic transition (or, at
least, sharp crossover) at the same temperature $T_{\rm u}=0.282 J$ as for
static properties due to unbinding of $\mathbb{Z}_2$-vortices. We show that
starting from the high-temperature initial state, due to presence of
$\mathbb{Z}_2$-vortices in the considering system, in a broad temperature range
$T<T_{\rm u}$ the dynamic properties in the intermediate time range are similar
to those of two-dimensional XY model below Berezinskii-Kosterlitz-Thouless
transition. The interaction of $\mathbb{Z}_2$-vortices with spin-wave degrees
of freedom does not emerge until rather long times.
