That was the Newtonian view, since we can expect that our runner can never run at relativistic velocities.
Considering Einstein, we need to consider that the speed of light is the ultimate speed limit, as far as we have experimentally detected. (Tachyons are still undetected.)
So the runner can never run at the speed of light due to the infinite gain in mass. But even if she could run that fast it wouldn't be enough. To a stationary observer, if she ran at the speed of light, it would take her 1/600,000 sec which is too slow and she would cause a black hole and suck inside the observer and the track and the earth, etc.
At very high velocities, time does some weird things, it slows down. Even our GPS satellites run at a slower time than the earth, in agreement with Einstein's equations.
If she could run faster than the speed of light, time might even go in reverse, which causes some really weird paradoxes.
Serious shit physicist here man ^^!!
Lets wait for 2 more days and I will disclose my answer here :)!!
You haven't yet disclosed it, have you? This is also my answer...
Boy, I love gentlebot