Here's some running sketches I did, ironically, really quickly.
This was meant as a help/critique image for
when he asked for help critiquing his work here [link] To Mr. Wrath:
I drew the lines on his shoulder really long to help show you the angles of the hips and waist from each other. Also, notice that while the right leg is forward the right arm is back at an almost equal extreme.
Also, due mostly to perspective (which in this case is pretty forced), when running towards the page the back leg appears to tuck behind the front one. Doing this gives the illusion of taking a step forward.
There's a lot more going on here too, but for the most part I hope this is clear enough.