How to add blur trails to objects in motion

First, my apologies for asking a question that I know for sure has been discussed but I do not know the terminology to use in a search and was unable to find an answer.

What I want to do is to take a 'runner' in a video and add those tailing blur trails you see to give the effect of motion, (accentuating the already present motion of running). I'm not sure this is even possible although I see often in videos - possibly created with some other effects application.

If there is a thread, and I'm sure there is, that deals with this then 'links' will be fine... youtube help videos even better. Thanks - JamesJM