What about, instead of doing something of that effort level (and energy system) that is broken up in the middle, something like 4×10' (no breaks) or 3×15' (no breaks) of progressively increasing effort level or pace (i.e. half-marathon to 10K to 5K)? This is a staple workout of the Japanese marathoners,
I heard/read about these type of workouts, but was not able to work them into my schedule (yet). Just to make sure I understand the concept correctly, depending on your target race you probably select the maximum pace of the last segment. So 5K pace is more for 10K/ half-marathon and 10K pace for a marathon?
Previews for a couple of Lynch's books:
It seems that this is already lingering on my amazon wishlist. It's probably time to have it ordered!