How many miles a week you should be running pre MDS is the big question everyone asks.
A google round other people's past MDS blogs shows huge variation. Some are extremely laid back about the whole process and do just that bit extra to their normal regime. Others go hell for leather mounting up multiple 12+ hour days out, fully kitted and booted up.
In my humble opinion I think less is slightly more. Marathon des Sables tests two main things out on you:
1) Being able to run (i.e shuffle) day after day with no rest
2) Being able to run long distances, by this I mean between 20-50 miles
With that in mind I slowly built in elements of these key things into my running foundation.
I built up back to back runs, from daily jogs to and from work, to 15 miles x3, to 25 miles x3. By January I was doing 15 miles back to back okay. There are many multiday races out there pre MDS to help you do this if you want it to be a bit more enjoyable.
I built up my distance. You need to be able to run a marathon fairly comfortably now and if you haven't attempted an ultra, you should aim to get one in at least. In my training I managed 2x 30 miles 1x 38 miles and 1x 45 mile race. By January I had done all this.
Running long miles takes it out of your body, and it took me far longer than I thought it would to recover from each race. In hindsight I would have liked to have done one more ultra race, just to give me the confidence more than anything, as they are pretty painful!
My weekly mileage tally shows I averaged around 40 miles a week after Christmas - not many miles really. Should I have done more? Yes I probably could have done with fitting in more solid back to back runs with a long run each weekend, but I managed to get round ok in the end. It was the shin splints rather than fitness which ended up as my problem out there. But that's the key - it's more about what type of running you are doing rather than endlessly tallying up the weekly mileage. Quality, not quantity. Your training should be specific to what the MDS is going to test you in.
Finally, pace! Well I ran at an average of 12 minute mile pace for my training runs. MDS will challenge your body like nothing else. It's the heat that means you can't run as you'd like to. If you are going out there with the aim of enjoying it and finishing it, stick with the snail pace as your body will become used to it during training (even 12 min mile pace is pushing it, much of MDS is unfortunately spent walking). If you are going for a top 250 place, you should probably find someone else's blog to read!
Seriously, if you are concerned with placing I would advise you to learn how to keep a steady pace and maintain it, bear in mind that 12 min mile pace is pretty rapid out there, learn how to run in sand and up hills, learn how to look after your feet and keep your pack lighter than 7kg. You can make up heaps of time as well by getting yourself to the start of day 4 feeling in a good way with your feet in good nick and getting it done with no sleep, as many competitors decide to sleep for a few hours before setting off again or are completely broken by this point so are ridiculously slow!
If I've got my maths right the winners run at 8 min mile pace and the slowest run at
22 min mile pace which gives you an idea of realistic pace.