I've recently been wondering if I'm running my easy days too quickly, so have been experimenting with going slower.
When I run 7:45-8:00 pace for an hour I feel pretty good when I finish; but if I go say 8:30 or slower, I end up feeling knackered. I finish feeling drained and generally a bit worn out.
All in all, the 8:30 efforts feel noticeably more fatiguing than 7:45.
What is going on physiologically? It feels like this doesn't make much sense. Is it possible in taking the 'slow down on your easy days' thing, a little bit too far?
For context, I'm in about 36min 10k shape at the moment.