I am a somewhat serious runner and I started to not only compare myself to the World Records as in I can do 70% of the WR for 400m but also to the age groups. It is fascinating that I cannot beat any under 70 record at all although I am very fit compared to the general population. So while old age is definitely a decline the achievable levels are still quite impressive. World records for 60 year old men are so good they might as well be the real WR for me