Error Prone Rotation

Once I had got the legs animating as they should, I began working on the swing of the arms. After I has set the keyframes for the arm rotation I noticed they were not doing what I wanted and expected, instead of rotating in a manor you can expect from when you run - in a semi-circular motion - they rotated out and back in along the way. You can see what I mean from the image below:

In this image the arm is in mid rotation as you can tell from the graph editor, yet it is not by the side of the hips like I expected to happen, it has rotated outwards out instead. I believe this is because the 'Max' model I am using was rigged in a T-Pose, and because of this it for some reason interferes with its rotation as it is not rotating from its initial rigging pose.

No matter how much I tweaked the tangents I couldn't correct the outward rotation. I finally remembered a technique shown in class about trying to correct such errors. We were told to use something called 'Euler Filtering'. I'm not quite sure what happens when you use this filter in terms of its technical details, but it does a fairly good job of correcting it. I would imagine Maya interprets which axis you are rotating and tries to cancel out the rest of the rotation, or averages them so that they help the rotation instead of messing with it.

The results can be seen below, they were not perfect by any means, but I honestly couldn't find a solution to this. I have a feeling its because of the rig as it is fairly basic, or maybe I did something at the start which caused problems later on, but I can't think of what it may be.

Eventually the arm rotated to a decent extent of what I wanted as it no longer rotated outward, however it wasn't as satisfactory as I had hoped for as it still came too close to the torso when rotating and at times part of the hand went through the body.