The following plan assumes that your training is at a level that you are ready to step up to an ultra. Don’t worry too much about exact miles i.e. 5.7 is close enough to 6 etc, also don’t worry if you miss a run , do not try to make it up just carry on with schedule. It’s important to increase the miles slowly while getting the back to back runs to really count without increasing miles too quickly. Do not worry about speed on the back to back runs, time on feet is the most important thing, speed comes from your Tempo and Interval sessions.
You will see that the back to back totals on 3 occasions are equal to your target distance and the totals for the week on 4 occasions exceed your race week mileage, this means that by the time race day arrives your body will have adapted to both the time on feet and the miles. Also and possibly more importantly you know you have exceeded the required distance.
The LSR is when to practice your hydration and nutrition, do not confuse hunger with thirst, drink to thirst (no one dies of dehydration in Scotland especially not in March) and eat little and often between every 15 to 30 mins. You need Carbs to burn Glycogen, run empty on carbs you run out of energy. Flap jacks, Brownies, Banana, jelly babies, I am a fan of real food but a gel can give you a much needed boost but be sure to try in training as well as racing, Your body can only process between 200 to 250 calories an hour any more is wasted, avoid meat, cheese, fruit except banana. You want some slow release carbs and the odd boost, the idea is to try and keep your levels balanced at all times during the run.
During training you need Glycogen for energy, if you run without Glycogen your body can very quickly go into catabolism (2/3 days) resulting in muscle loss, fatigue etc. So you need a sensible diet, around 65 % Carbs 25% protein 10%good fat.
Cramps can be a real issue for some folks even on a healthy diet you might find that the increase in work load on the Back to Backs require salt tablets or Nuun as an addition to your water during runs.
George