I did my heart rate test this morning. I won't repeat all the gory details of the protocol, but suffice to say it involves running a 2.15 km lap of a park at a standard heart rate after a standard amount of warm up and recording the time. Well, the last time I was able to do it, the penultimate week before Tokyo Marathon, I recorded 4:04/km for an average HR of 149 (80%). On that run, and around that time in general, I was finding my heart rate incredibly low, and I would have to work my legs hard to get up to target heart rates.
Today it was a different story: 4:15/km. Yikes. And it was definitely hard to stop my heart rate slipping up to a higher level; the average for the lap was in fact 150 instead of the target 149. I noticed the same tendency towards slightly higher than expected HR during Saturday's and Sunday's runs (I'm sorry now that I wasn't wearing the monitor when I felt so sprightly running the Palace in 19 minutes last Thursday!).
So the million dollar question is: Is this a reflection of fitness lost during the low mileage of the taper and recovery, or is it lost fitness through the battering of the marathon itself, or is it a reflection of not yet sufficient recovery?
My hunch is that it is a combination of all three and it would be impossible to disentangle them. If you simply didn't run, by the time you were "fully recovered", whatever that means, your fitness would surely have slipped. I mean, I couldn't sit on my arse for three weeks eating fruit and protein shakes and then come out and run the test at 4:04/km again could I? Yet if I run too hard, residual fatigue from the marathon will knock me around and again, the test results will suffer. So you are supposed to come back gradually, in a reverse taper, repeating the stimulus training runs, and eventually at some point you could re-hit the pre-marathon test results.
I suppose the moral of the story is that when you run a marathon, it takes a fair while before you come back to your pre-marathon condition. And you have to really train again to achieve it. You don't just "recover" to pre-marathon condition in the way you could with a 5k or 10k race. Well, that's as measured by this test anyway. I guess there are other energy and endurance systems that I am ignoring completely.
Today: 15.3 km, average pace: 4:35/km; average heart rate: 140 (75%)