Stepping motors usually require a high voltage pulse (high being higher than the winding voltage at the nominal operating current) to reduce the effect of the L/R time-constant and give a fast current rise in the inductive winding, which is then typically followed by a lower voltage/current hold to minimize power dissipation in the motor.
This is often done with a power resistor in series with the winding or a constant-current circuit, both of which waste significant power in the resistor or...