LSD runs, long slow distance runs, with 'slow' being a relative word, of course. The real idea is to run totally within the aerobic heart rate window. I could not do that yesterday, but like I said before, coming back has to be earned.
Regarding heart rate and running windows, I will share what I will use and why. The first thing to have in determining workout zones is maximum heart rate. I prefer to use Tanaka's equation, which is based on a study he did for a wide range of ages, even up to 90 years old:
HR-max, Tanaka = 206.9 - (0.67*age) (+/- 6.5)
For me, the above equation tells me my HR-max is 168.7, but could be anywhere from 162.2 to 175.2 bpm. Now, armed with an estimate of my maximum heart rate, I know that the aerobic window is 70-80% of HR-max, my aerobic heart rate midpoint would be 126.5, with a possible range of 113.5 to 140.1 bpm. That is a wide range, and one has to determine by feel what works best for them.
The above discussion involves a 'straight percentage' of HR-max to determine zones. What running coaches and serious runners seem to use is the "working heart rate" (WHR) method, proposed by the Finnish cardiologist Karvonen, for athletes. Karvonen's method takes into account the resting heart rate when estimating workout zones.
WHR = HR-rest + ((HR-max -- HR-rest)*target zone percentage)
One still needs to calculate or measure a HR-max, and measure HR-rest, usually done before getting out of bed in the morning, before any activity. Mine is 53 bpm. My aerobic range (70-80%), and accounting for the statistical variation in the HR-max calculation as before, is 129.44 to 150.8 bpm.
I will be using the Tanaka method for HR-max and the WHR method for determining workout zones. The numbers are not exact, but are meant to be a guide, and as for me, having looked at every heart rate maximum equation going, and what others use to determine zones, I am going with what I have stated and sticking to it. It keeps things simpler.
What else can I say about this run? My running dynamics were good except for cadence. It was still around 200. This is wasted energy. In the recent past I could run anywhere from 6 mpm to 12 mpm at 180. I came home and replaced the batteries in my digital metronomes, as this will be a focus of next week. By the way, do not count run cadence with your feet -- count it with your arm swing, as it has a more consistent feel throughout the run. I made this run with better balance, though not perfect. Better is still progress, so I will take it.
Next week the intervals 'progress' to 3x2, or roughly 150 m by 100 m. Gradual progress, and paying attention to the right things...