To see the effects of aging on running I have made a table and plotted the results of my running the Mt. Washington Road Race for the past 12 years. In 1997 I was 46, so in 2007 I was 56. The race is 7.6 miles up the Mt. Washington Auto Road. The average grade is ~12 %, and there are no flat or downhill sections, just different degrees of up.

year	1997	1998	1999	2000	2001	2002*
time	1:25:09	1:22:25	1:18:08	1:23:51	1:21:32	37:12
overall place	77th	61st	49th	43rd	43rd	91st
place in age group	9th (45-49)	5th (45-49)	5th (45-49)	5th (45-49)	2nd (50-54)	4th (50-54)

* The 2002 race was shortened to halfway-to-the-top due to dangerous weather on top.

year	2003	2004	2005	2006	2007
time	1:22:18	1:26:44	1:26:12	1:27:52	1:26:46
overall place	59th	112th	103rd	108th	98th
place in age group	3rd (50-54)	8th (50-54)	9th (50-54)	3rd (55-59)	5th (55-59)

The Mt. Washington race is approximately equivalent in effort and in time to a half marathon. Thus I have also complied and plotted the results from running a half-marathon over the past xx years. The courses differ, so that introduces some unwanted variability. Nonetheless, one interesting trend is still clear.: One slows down at a faster rate with age for the flat races, i.e. leg speed is affected more than oxygen processing (which is what is important for a pure hill race like Mt. Washington).

year	1991	1993	1994	1995	1996
race	New Bedford	New Bedford	New Bedford	New Bedford
time	1:17:02	1:19:42	1:22:08	1:22:06
overall place	133rd		165th	176th
place in age group

year	1997	1998	1999	2000	2001
race			Melrose	Melrose	Melrose
time			injured	1:24:16	1:23:54
overall place				333rd	324th
place in age group				42nd (40-49)	28th (40-49)

year	2002	2003	2004	2005	2006	2007
race	New Bedford	Wakefield	New Bedford	New Bedford	New Bedford	New Bedford
time	1:22:59		1:28:21	1:28:21	1:28:37	1:36:23
overall place	223th		255th	266th	269th	467th
place in age group	9th (50-59)		15th (50-59)	22nd (50-59)	23rd (50-59)	55th (50-59)