I'm training for my 3rd marathon which is 4 weeks away. Last week I did 20.5 miles in a decent time (2:56). The week before I did 18 Miles (2:35)
This week, I was aiming for 22 miles. I didn't really do any training during the week (had bruised toes). During the run, after about 9 miles I felt that my legs were very heavy. Rest of my body felt great though. I eventually had to stop at 16 miles as my legs were so heavy and my pace had slowed significantly.
Do I need to rest more between runs, or is this because I didn't do enough (or any) short runs during the week to keep the fitness ticking over and get rid of the lactic acid?