I have mentioned the prospect of going through 18-20 miles as your final run before the marathon, perhaps I should re-phrase that as your final “long” run before the marathon, ideally done 2-3 weeks before the event takes place.
You need to be able to do this distance or you are unlikely to be able to complete your marathon. If you are still struggling on 12-14 miles for instance, then you are putting yourself at severe risk doing the marathon.
You are risking injury or even strain on your heart by trying to make such a big jump up, and it would be very unwise for you to attempt a marathon in such physical condition. This is why I give people plenty of time to get their training in for such a monumental run.
Things can and do wrong.
If you have a sore Achilles for instance, then you need to rest full stop until it gets better. This can take 3-6 weeks depending on the severity of the injury.
Indeed, if you pull an Achilles, you will certainly have to pull out of the race, and will probably never run long distance again, but I stress that this is pulled Achilles, and not a slight strain.
Its allowing for these minor mishaps and injuries that will dictate your training programme so please give it more time than you thought!
So once you have overcome all these obstacles along the way, then it should be around 2-3 weeks left that you attempt your biggest distance, after carefully working up to it over a period of weeks, and indeed months when you take your whole programme into account from start to finish.
If you can finish this distance, then you know you should be able to complete the marathon, but bear in mind it is still very likely to be a very hard day.
More on that day tomorrow!