She lifted her chin, defying him to lash out at her again.
In jumping an ordinary hedge or ditch at moderate speed, there is of course a moment of time during which the horse is on his hind legs, and in theory the rider should then lean forward, but, in practice, this position is so momentary, and the lash out of the hind legs in the spring is so powerful, that it is best not to lean forward at all, because of the difficulty, if not impossibility, of getting back in time for the reverse movement, when the rider should be preparing to render the horse some assistance with the bridle as his feet touch the ground.
At least she is so placid and mild that she doesn't lash out.
PM inclined to lash out at all & sundry & rather petulant.
Many people see anger as an uncontrollable emotion that causes people to lash out.