1) get a two-handed weapon, and attack a zombie (might work with any weapon)
2) get hit by the zombie (mid swing, maybe even without mid-swing hit)
3) put away the weapon
4) notice your character moving very weird, you seem to be running with normal speed, but you will be pushed back constantly, as if you are running against very strong gushes of wind
5) raise and lower your fists, you are now moving normally again