Oh, I thought some of the newer watches with the built-in wrist-based HRMs (so no need for a strap ) did vertical oscillation, but it makes more sense from a chest strap. Though I can tell if I'm bouncing up and down or not.
Bob bought me a coffee and a bacon roll once, so I can confirm that he exists outside of running.
In my research of marathon training programmes, guidelines and advice, I've come across quite a bit of conflicting opinion about exceeding 20 miles maximum distance for long training runs for a 1st time marathoner.
What are your experiences and opinions, please?
I think it depends what kind of 'first time marathoner' you are. A lot of the advice is aimed at people who are 'beginners' both at marathons, and at running more generally, i.e. people who have started running in the last year or so, have maybe (but not necessarily) built up through the distances, and are now aiming for their first marathon. Those people probably don't have that many miles in their legs in total, are doing a 'get you round' training schedule with not-too-high weekly mileage, and may well find it very difficult to run 20 miles, especially as this might represent 50% of their miles that week. If this is you, that's a good reason to follow the 'don't go over 20 miles' advice.
However, if you're someone who's been running for longer than that and were used to running 3, 4 or 5 times a week already before the start of your marathon schedule, have done a few halves, etc., then there's no reason to see yourself as a 'beginner' even if it's your first marathon. In that case, there's no harm in building in a few more 20-milers, for the benefits people have mentioned above.
I actually don't mind the HR thing as much as Skinny does, but I find the speculation about what the figures mean frustrating because most of them (and especially the estimates produced by the newer Garmins just for the sake of having extra metrics and which are probably not particularly accurate anyway) probably don't mean much when it comes to deciding what actual training you are going to do.