Why is lane one left open in track and field?

Question

Why is lane one left open in track and field?

Answer 1

just incase someone falls they can get up.

Answer 2

they don't need to use all of the lanes, also the left lane has the shortest distance to travel.

Answer 3

Most athletes don't like lane 1 because of the tighter turns than

the rest of the field.

Answer 4

They are using lane 9 instead as the bend is not so tight

Answer 5

The inside-most lane has a very sharp turn, so it's asking an athlete to be tilted towards the inside for much of the race.  This makes it an unfair disadvantage for him or her.  It's much easier to cover the same distance by running straight than running in a small circle the whole time.