Lagat is a good example because he has a very powerful sprint. Look at Lagat's hips in any video. They do not bow out, which is what the blue shirted runner has to do to keep moving. He has to shift his opposite hip outwards when his stance leg (the one on the ground) strikes directly under his midpoint.
If you told both runners to run along a lane line, the guy in blue would run directly on top of the stripe, while Lagat would likely only touch the outsides of the white stripe. Lagat, like many distance runners, has a foot strike just barely to the outside of his midpoint (many times straight down from the outside of their head) and not exactly straight down from his narrow hips. It's close, but it is not so far under that he needs to ride his hip way out to pull forward.
If Bolt ran between lanes, he would not touch any part of the white stripe.