RunHarwell wrote:How far could he get in six months? A year?
With serious training for those time periods he could drop 2-3 minutes off his 5K in that year.
But quite honestly he may hit diminishing returns fairly quickly after that if he's done no AT training at all. Some years back when I was studying such things I came across a series of studies, one of them discussed at an RRCA conference presentation by Jon Sinclair.
The jist of it was you can lose potential, and never get it back. There's a natural loss of aerobic threshold over time, but training slows that process (quite dramatically). So if you start fit and stay fit you're going to lose a tick or two every year but it's a slow decline, but if you don't for the most part it ain't coming back.
So if your 25 year old male was training at a high level in another sport, then decides to become an elite runner a percentage of that translate but they'll never reach the potential of an equivalent 25 year-old male that started at 12.
If they basically farted around for 25 years and didn't train for anything they'll get to be a decent age-grouper, but the odds of them being "elite" is pretty much nonexistent. If they hang around for 50 years they might be able to set some 75 year old world records, as long as the guys that started at 12 don't hang around too.