Remember adrenaline, and running is an instinct - so there's every chance that an injured person would run quite normally - maybe hunched over holding their torso or something. For realism, I would suggest having a few variations. So if someone is shot in the leg they might try and keep it straight, but still they should be able to move at a decent speed unless they stood on a landmine.
What would be cool, is if once they stop running, they just flop over in agony, then they can't do jack, fear takes over and adrenaline wears off. Same might apply if they fall over while running, they probably wouldn't get up again.
Health, Ammo, and bacon and eggs!