Somebody tossed me this tip a few days ago.

Turn off post-processing within the Graphics options of the game.

(Feel free to bow down and kiss my feet afterwards, I know you'll be wanting to thank me greatly. ;-)

I don't know why they're using blurry screen texturing for simulating simple exhaustion. From my experience, blurry vision never occurred to me when running greater than one mile! I doubt many others experience similar blurring as well. Not too further mention, they're really using some really excessive blurring!

I'll gander blurring does not occur, unless somebody is near to blacking out or death. Personally, I don't like the blur effect at all and prefer to switch it off. Slowing a person down, or blacking the screen performs just the same.

it only happens to me after running a distance of a mile or more at a really fast speed. Like a mile in 6-minutes and occasional bits of sprinting after with no break. I guess they are trying to show that you cant focus on things very well for a bit. but it does seem to happen to fast

Try running as a pilot.

Able to run 50-100 feet, and then nothing but blurred vision.

If you're a runner, you'll know your vision never blurs this badly including the heavy breathing. It's as if the game simulates a smoker or somebody whom doesn't exercise.