I think if you swing side to side quite a bit when you are running, it is down to back/core strength, as Daniel Andrews mentions. I used to rock quite a bit, as did other members of my training group, and when we introduced a core session 2x per week, our technique tightened up a lot, which was positive.
In terms of the arm swing, I generally think that the arm swing is a result of something else happening somewhere in the body, like tight hips, and that by fixing your arm swing wont actually change the problem.
Obviously, I have said all this without seeing you run, so take it with a pinch of salt!
The arm swing comments, come with two “parts.” One is my elbows coming out, the other is my arms not coming high.
I’ve figured myself that im not going to try and bring in the elbows, and coach says so too as well for that. So should I also not try to manually bring my arms UP (near face level) vs. arms staying low?
Just overall core work also would be useful? Cause I’ve done quite alot of rotational core work.
Bt one thing though, is rocking side to side potentially good for the drive phase? And when in speed endurance running, is it essentially causing me to slow down quicker than if i didnt rock?