I don't think it makes a jot of difference to your speed whether you are 36 or 39. I'm 40 next week and run faster than some 25 year olds and slower than some 60 year olds. We have an ex-elite runner at our local parkrun - she's in the V55 category and wins the ladies race on a regular basis.
It depends on how long you've been running, your physiology, natural talent and I guess just how much work you're prepared to put in.
I don't have a problem with the age bands but I do wonder why some races offer more prizes for men than for women - eg Bramley 10/20? I'm assuming it's because more men take part.
As for the Race for Life, I can see why guys get a bit miffed but there are so many other events, and so many other cancer charities. The RFL events aren't timed or competitive, but it is nice for ladies to have ladies-only events that they can actually win because there are always loads of men in before the ladies unless you have a very elite lady taking part - I did see a lady come second overall at our parkrun once. For example, I've been 4th lady in an event but 34th overall.
Edited: 02/03/2012 at 12:03