Cram says 5 years is what most top ranked athletes have to remain number one. And once the gods lose that unbeatable status they quickly fade. Look at Coe after 85, Aouita after 89, and Morceli after 96. The training is so brutal the incentive probably lessens once you're up against a newcomer who appears challange you. And of course age sets in.
I always though John Walker was unique in that he kept running long after his best years and finiished in the middle of the pack. I recall Aouita completely shutting down at Worlds in 91 when Morceli ran a 51 last 400. And then remember Morceli stepping of the track when he could barely stay with El Gurrouj's pace at Worlds in 99.
So what is the typical life span for a number one track athlete. Certainly there are many exceptions to 5 years, but is this the most typical scenario?
Coe 1979-1984
Cram 1983-1987
Aouita 1984-1989
Michael Johnson 1990-2001
Carl Lewis 1983-1991 (not as effective in sprints after this)
Gebresellaisee 1995-2000?
Barrios 1987-1991
These are only a few but it appears that 5 years may be the lifespan that is most typical. Can anyone come up with a long list of dominators that differs from this?