Race report: Cougar Challenge 8k

I had a pretty good running week. Did 7-mile runs on Monday and Wednesday - longest runs in years. I couldn't leave well-enough alone, though - had to run another 8K race this morning.  I had it in my head that I should be able to average 8:30/mile - even though almost all my "training" is at 10-11 minutes per mile.  I ran the first mile in 8:05 and I was in last place! Let the record show that there were separate races for men and women today.  I got slower as the race progressed and my legs became more wooden - I ended up averaging 8:48/mile.  It would sure be nice to feel some spring in my legs again some day (being 174 lb. doesn't help). Anyway, the last mile felt like mile 22 of a marathon and I was very glad to get it over with.  I never seem to be able to catch those white haired guys way ahead of me. Who are those guys?