I've ramped up my running recently, longest run was half marathon distance. Rest day today (wen't climbing) but the last 3 days I ran 3 * 10km CX.
I don't in running but I do in cycling and walking/hiking.
I felt the same, but today I was coming round to the full Marathon distance .
I would love to tick the three events off in one month. I'll try and get a half marathon CX distance in tomorrow and see how I feel after but for now I'll stay optimistic.
I'll prefix everything by saying that I am beginner and only started serious running this year, I am training for my first marathon. What I say is based on what I have read, and my own experiences getting my casual 8-10mile runs to be at the 18mile distance, the longest I ever ran so far.
Given the time line and your distances I would say you are in over your head. I don't like to be pessimistic but I think to run a marathon you probably want to be running 40mile per week with long runs to around 18miles. Beginners probably want to have long runs going further, and have a second medium long run to 13-14miles per week. And have that training in place for 3 months.
E best thing you can do at the moment is sit on your arse most of the day. Read up on tapering. Day before eat as much simple carbs as comfortable). A run walk strategy is really going to be your best hope of a running finish and a reasonable time. It doesn't slow you down as much as you think ( if you spend 10% of your time going half the speed then you have only lost 5% of your time which is easily made up by recovering muscles).
The hardest thing about my marathon training is running slow enough to maintain endurance. You only have a certain amount of sugar in your body, once deplete you are burning fat which is very hard. Your aim is really to get your body to use as much fat as possible through the early part of the race so as much sugar is left for the end, or at least you have pushed "hitting the wall" to as late as possible. My understanding. Is beginners will run off the start line thinking they are running slow but they aren't, 10-12miles in they might start noticing and slow down a little, at 16-20miles they hit the wall and their muscles collapse.
Ideally, you want a negative split, so the second half ideally is faster than the first. Think about that when you leave the starting line. A load of people will pass at the start and it will feel like you are running slow and you will speed up, but this is. Is take that can't be recovered later. If you run slow at the start then 3 hours layers you have some hope of still running at a half decent pace, and with any luck you will start passing people that left too quick.
Remember that 20 miles is an incredibly long way to run, some thing most people just simply physically can't do, and you really need good physiological adaptations to run that distance. You then have a full 10k race to do on the tiredess legs imaginable. That is when training, pacing, blood sugar, strangely mental strength comes in. You then have up to an hour or so to suffer, and you want to minimize that suffering that last 10k gives plenty of time to over take others if you have paced yourself right, make up time, go for fast finish. Of course it gives plenty of time to suffer and drag your arse towards the finishing line.
