In reply to tom_in_edinburgh:
> What I should have said is "If 'running a marathon' is to mean anything and we are talking about people without disabilities and not special circumstances like hill running it needs to be faster than everyday walking".
Excluding special circumstances, plenty of people train hard, but still run quite slowly.
> People see 'running a marathon' as a challenge and worthy of respect. When you start allowing 6.30 on a normal flat course to count as running a marathon all you have achieved is to let everyone succeed by removing the challenge. It is supposed to take some serious training but at 6.30 a relatively fit person could put on hiking clothes and carry a day pack and walk it. That's not what is meant in everyday conversation by 'running a marathon'.
I suspect it is actually quite challenging to walk a marathon in 6.30, it is faster than most people walk even short distances, but yes I sure that some reasonably fit people could do it. They would definitely be above average though.
> There has to be some kind of time limit or would you allow someone to walk 13 miles, book into a hotel overnight and then do the final 13 miles the next day? It seems to me that taking normal walking pace as the slowest acceptable is a fairly reasonable rule of thumb.
Lets use your rule of thumb, the problem is, your 'average' walking pace is well off, most people walk quite a bit slower than 4 mph, 3 mph is much nearer the mark. That is getting on for 9 hours for the marathon.
> All the discussion about high speed walking being faster than many runners is entertaining but beside the point because if these were high speed walkers they wouldn't be taking 6.30. Similarly, any kind of continuous running like movement is going to get you there before 6.30 unless you take an hour out for a rest.
I know a lady at my club, she is late 40s and carrying a little extra weight, but by no means obese. She ran a marathon not long after joining the club and ran it in around 6.30. I know she trains hard, she often does sessions that I organise, whilst she isn't fast she gives it her all. She races regularly, 5k, 10k, half marathons and marathons. She runs all the way, she is sub 6 hours for the marathon, but not by much. She is definitely running, just slowly.
Judging other by your own physical standards isn't always wise. I could go out tomorrow and run a 3.30 marathon on no specific marathon training, many people would be very pleased with that time, but I would have put far less effort in to marathon than many people running much slower. It is about the personal effort of that person, time doesn't always tell you that.