Really?? wrote:Is there any empirical evidence to support this? Is there some documented physiological reason?
Personally, I think there's some truth to this in a general sense, but there are exceptionsto every rule. I have some running friends who were "elite" when younger who simply can't train themselves back to a decent competitive level (say, equivalent age-graded times). Personally, I've run all my life, but only competed seriously since age 35, give or take, and at 43 nearing 44 I've set new PBs every year in the last 6-7. So we fit within this general rule.
On the other hand, you get guys like Steve Boyd who's been competing at very high levels since he was a teenager, and is better, in relative terms, in my opinion (i.e. "more elite") now as 45 year old than ever. Also, Jerry Kooymans was a strong NCAA XC runner, and at ~ 55, he ran 16:04ish this past summer, so he's also still going very strong.
My own experience would suggest that the majority of aging runners fall into the general rule you refer to, and there are a reltively small number of runners like Steve and Jerry who maintain a very high level for 3+ decades.