A professor friend of mine recently introduced me to the blog FemaleScienceProfessor, in which the blogger writes:
"From a teaching evaluation (not mine, but it could have been):
'The professor paced without purpose while teaching.'
I confess: I pace while teaching. To the extent that my pacing has a purpose, it is so I can be a physical presence in various parts of the room at different times during the class, make eye contact with more students, listen to their questions better, try to see what they are seeing when I project something/write something at the front of a large classroom, or just because I get kind of hyped up when I teach and I feel like moving. I don't know if those are good purposes or bad purposes, but I think they add up to purposes, even if students don't know what they are."
Movement in a presentation is very powerful. When you move purposefully, you drive home your content. When you move randomly, you likely lose your audience.
It seems the professor here does some of both.
There is a big difference between walking towards a student in order to listen to her question and pacing back and forth "because I get hyped up when I teach and feel like moving."
The former is purposeful - and helpful. The latter may be a way to get out energy - but is most likely distracting to the audience.
From the Green Room: A speaker can ramble in words and in movement - both are problematic. Just as you speak with intention, you should also move with intention.