The dependence of exchange bias field on magnetic field sweep rate was investigated for [PtCo]3 t PtIrMn multilayers. For structures with t=0 nm and t=0.3 nm, the bias field decreases above a field sweep rate of a few T/s. The observed reduction of exchange bias at high frequencies correlates with a magnetization reversal asymmetry at low field sweep rates. Multilayers with t=0.1 nm exhibit symmetric reversal and constant bias. The correlation between exchange bias dynamics and magnetization reversal asymmetry is explained by the frequency dependence of the domain wall motion to domain nucleation ratio.