When I started to run competitively, one of my training buddies told me that just because you're younger and have been running for years, don't be shocked to see someone 10-20 years older pass you by. Your ego won't get it, but trust me it will happen. And sure enough, when I started to race 5ks and 10ks it happened. In one race, someone who could be my granny sped by me like the Roadrunner, and yes, my ego was bruised because in theory I should have been faster than a AARP member. Youthful arrogance I tell ya!
The NY Times ran this interesting article, "See Jane Run. See Her Run Faster and Faster" where writer/runner Gina Kolata points out something that appears, on the surface, to be unusual in running races: older female runners tend to out pace time wise their younger counterparts. Gina shares her observations: