No, not listening to “Rock” when running, has anyone experienced the sensation of when they are really giving the track heaps of power and speed, the body feels like its rocking back n forth from the power? Arms really pumping, shoulders and jaws relaxed and i even pulled of a PB over 140m. So, is this rocking good, bad, ugly or awsome?
As long as the rocking doesn’t throw your form off, you’re good.
Just think about Kim Collins and his side-to-side head action. 
He does just fine.
Not when running maximally, but when I run submax reps I feel that sort of feeling, because of the lowered frecuency and increased ground contact time it’s like each stride contacts for longer and the body goes forwards and back as the foot is on the ground till its further behind the body (and one gets the feeling like one is delivering so much more power then when going faster, though we know this is a fallacy).