hehehehe, time to show off my knowledge of parkour...
keeping your tori's torso at a 60-75% angle is very important when doing a basic 10 tf run. this allows for good balance, while keeping forward just enough to gain momentum.
if you're looking to get over obstacles, becoming more straight helps, although its fore more experienced players. don't use your abs solely to lean back up, hold your planted knee to gain that lean back. it also helps if you've leaned too far forward and need to get back up. another way to help that, if you're leaning too far forward is to pair holding your planted knee, and contracting your other knee. it's not pretty, but it works.
also, try not to be bouncy and dippy when you're running. it doesn't look cool, and it actually hinders you. try to keep as level as possible when running, it'll help you take that next step.