I've been watching my Performance Condition lately (added to my data screen), and notice that it shows my best perfromance when my heart rate is pretty darn slow. Here are my personal stats:
56 year old, 6' 1", 185 lb male. I run 40 to 45 miles per week, averaging a 9 minute mile. That 9 minute pace, keep sme in the high areobic (green) zone. If I want to hold an 8:30 pace, that puts my heart rate in the threshold (orange) zone, around 157 bpm.
In order to keep my Performance Condition in a positive state, say +1 to +3 range, I have to keep my HR somewhere around 130 bpm. This is a 10 to 10:30 pace for me and feels really slow.
This is really a big picture training question for me. I know that the body is most aerobic in the 70% of max HR range. I believe that "most aerobic" means that you're burning primarily fat. As you get closer and closer to becoming anaerobic, you start burning more sugar, until you become completely anaerobic and burn all sugar, and the body starts dumping lactate into the muscles to shut them down.
Common sense (in my peanut brain) says that if you want to get better as a runner (faster and able to run farther), you should run, most of the time, pretty hard. It seems like you should be really tired and huffing and puffing when you finish a 5 to 7 mile run. I would consider running "pretty hard" as somewhere in that high aerobic to threshold zone. However, the Performance Condition says that I'm performing best in the low aerobic zone.
Here's the BIG question...If I can currently run a 10 minute pace at a HR of 135 bpm, even though this seems really slow, if I train solely by HR, always keeping it at 135 bpm for the next 6 months, would my pace at that HR probably become something closer to a 9 minute mile, giving me plenty of extra HR for harder runs (like a race), or would I just stay a slower runner?
Thanks, Grey