Facial Animation for Run Cycle, Run Cycle Complete

I have finished my facial animation for the run cycle of my character. I aimed to show him breathing heavy and fast, just as you probably would when running for an extended period of time, but I have also aimed to show him angry or rather him having the intention to charge an enemy, and as so has a facial expression that shows him wanting to attack something or someone.

Here is the facial animation:

The loop is only 19 frames long. I believe for the overall animation I have managed to apply good animation principles to produce a believable and appealing result. However, 19 frames is difficult to fit in facial animation that accurately and finely conveys what I character is portraying. That being said, I think the audience that watches this facial animation can understand those points, even though it only has a short amount of time to represent them.

I also recognise that because it is such a short loop, any big or noticeable actions will be repeated over and over, and therefore become obvious that it is a loop which is not really what you aim for in game animation. So I made a facial animation that looks as if it should be looped, with the character taking heavy breaths and looking angry in them too.

Here is my final run cycle animation as seen from multiple angles. I believe the body movement and facial expression compliment each other and show a good amount of exaggeration and secondary action, among the other principles of animation that I have applied.