Chinese recovery run torture

What's harder? An 8 mile steady pace run at 80% of Maximum Heart Rate or an easy recovery run of 6 miles at less then 70% MHR? This isn't a joke along the lines of "What's pink and hard in the morning?*", but a question that get's to the core of the base training philosophy.

A lot of folks will talk about "junk mileage" and the need for quality. If my recovery runs are junk mileage then why are they so tough?

Each week I do 2 'work sessions' - they are what most people call quality sessions but they are not the classic anaerobic, eye balls out, puke your guts up sessions that some seem to love (?!). They are aerobic sessions, run at higher heart rates but still below the aerobic threshold, typically (for me at least) a medium distance (6-9 miles) run at 80% MHR, or some long intervals of 1-2 miles run at 83% MHR. The aim of these runs is to slowly push up the aerobic threshold so that ultimately I will be able to sustain a higher heart rate in the marathon. Monitoring the aerobic threshold is by means of examining cardiac drift, but this is a subject for a later post.

The days following the work sessions are easy recovery runs, to put me in good shape for the next work session. I believe that far from being 'junk mileage' these runs get to the heart of the base training idea and the need for daily running. By running tired and depleted of glycogen they train the fat burning system (this might just be my opinion rather than statement of fact - comments welcome). I also believe that no mileage is 'junk' when it comes to improving your aerobic efficiency. The following day I feel great, so there is a benefit there.

These recovery runs feel tough though, unlike the work sessions when I'm fresh and ready to go. I seem OK for the first few miles of the recovery run, but as the distance ticks monotonously by I get a really hollow feeling and it becomes more of a struggle to keep going.

So after 5 miles of running on empty, we have the following inner dialogue:
Head: "Only another mile and we're done"
Heart: "I'm cold and tired and I want chocolate!"
Head: "We need to do at least the same mileage as last week. Another mile is nothing"
Heart: "My knee hurts, the bruise on my hip hurts, and I want chocolate!!"
Head: "This isn't junk mileage. These are the bread and butter runs of base training"
Heart: "What if my knee isn't just tired muscles but the return of ITBS? Chocolate and a sit down will help!"
Head: "A nice vegetable stir fry with peanut shoots and cashews awaits us - far healthier and better for recovery. Come on - less than a mile!"
Heart: "I want chocolate!!!"

In the end 'we' compromised and did 5.5 miles. The 'chocolate' was an SIS Rego recovery drink, chocolate flavour. The stir fry went ahead though - I quite like them!

*and to answer the other question: The Financial Times crossword. Surely you knew that old chestnut?