I didn't start running till the day after I turned 40 and didn't run my first 10k till 5 years later. After the 2nd year of racing, I was consistantly breaking my age.  It was like bowling a 300 game. Unfortunately, I have not been able to shoot my age in golf.  My goal now is to run a marathon when I'm 90, and let any other's in my age group go ahead of me as I will want to let them win their age group, as I will want to tell them, I'm coming back next year again, and I don't think you other guys will make it (Ha)  This was a true story at the NYC Marathon several years ago when ABC was still televising it nationally, and they interviewed 3 men all over age 90, and wanted to know who was going to win their age group.

Cool, I didn't even know about this running a 10k in your age thing, but I got to checking my last 10k when I was 48 1/2 and sure enough my time was 48:36. I suspect it does get easier with age as long as you stay in shape, I think I could do at least that good now, a year later. I've cut my mileage a little, but that would be a good guage on how I'm doing, if I can do a 10K under my age I'm doing good.