I remember seeing a video that talked about the physics of boxing, specifically rolling with the punches. It clearly works, people who roll are hit much less ha

I remember seeing a video that talked about the physics of boxing, specifically rolling with the punches. It clearly works, people who roll are hit much less hard. However, a champion boxer hits at ~90MPH. You can't jerk yourself back fast enough to make an appriciable dent on the KE of the punch. The effect is almost all in the dt of F=dp/dt.