Thank you for all the replies folks.
Breakfast is a bowl of porridge and half a banana. She makes sure to drink a couple of glasses of water beforehand, and takes some water with her whilst running. Her pace is slightly slower than that of the shorter runs during the week and she has dropped the Wednesday night run, as she was finding four runs too much in a week now they are all getting longer.
She is happy with the amount of sleep she is getting, although I think an extra hour wouldn’t hurt, and I know the night before the race we’ll both be getting to bed a bit earlier. Alcohol consumption is almost zero, and we never drink the night before a run so it’s not that either.
Not sure about running on “empty”, but I understand what works for one person doesn’t for someone else, so that is something else to consider. I did mention dialling back the distance of the Sunday run, but that idea didn’t go down very well. She is keen to keep the Sunday runs long to help prepare for the race. But as I mentioned above she is now dropping the Wednesday night run, so that may help. If that doesn't work then reducing the distance for a week might be a good idea.
It’s clear she doesn’t have the energy she needs first thing in the morning, as she felt drained within the first couple of miles and it’s just a case of finding the right balance. We are going to pop into our local Sweatshop on Saturday and have a chat with the staff and maybe pick up some gels. Maybe adding an energy drink during or possibly during the run might be enough.
Edited: 28/01/2013 at 15:13