Interesting question, and one which I tested this year
.
Did my first 100miler early March, Thames Path (okay I got to 91m, then they cancelled the race cos of the weather, but I still had 4hrs+ allowed time left to finish it
). However, I had already pre-entered the Connemara marathon a year in advance, well before I knew I would be contemplating TP100. This was set for early April, giving only 4wks recovery.
So, Connemara is generally regarded as a tough marathon (the 'Hell of the West'), I was expecting, based on my times for Cape Wrath marathon which I would say is comparable with the climb, about 4hr 30m, in the end it took me 4hr 50m to complete Connemara. So, my price for 100miles - 20mins added to the marathon time, and legs that did not want to climb hills
. I plodded it and finished, and that finish felt good
.
Rather strangely maybe, another 4wks after that, I did the Highland Fling, 53m on the West Highland Way, and knocked 15mins off my finish time for the previous year!! Horses for courses maybe, but I felt the 100 had made me stronger, given enough time to recover, and running trail rather than road.