I know this is an old post, but I feel it deserves to be addressed.
First, the issue is, if you've ever seen a person run fast, as the angle of the body suggests, the head and arms move a lot farther forward and bounce a lot more, both up and down AND forward and back, usually at a diagonal in this view. Another thing is, on the legs, there's no hint of the hips or shoulders turning in opposition as he runs -- this is kind of mandatory for that kind of locomotion.
The distant arm kind of doesn't do much and suggests the shoulders aren't turning as much as they really would in a brisk run like this. The arm would disappear, not hang forward for no reason (unless he's looking to grab something with that hand). Make it straighter and swing a bit more a bit sooner too, and you'll be on the right track.