Lactate Threshold and HR Training Zones

I've decided to utilize Matt Fitzgerald training zones based on heart rate at lactate threshold effort. His zones, with the focus on lactate threshold heart rate, are very similar to Joe Friel's. You determine your lactate threshold (LT) heart rate by one of several test runs. The simplest is to run 30 minutes very hard and use your average heart rate for the last 20 minutes as your LT heart rate. I've gotten pretty good at estimating my lactate threshold based on increased breathing rate. Fortunately, the two methods (rapid increased breathing HR and 30-minute test) give me the same result. So did my metabolic fuel test (with less precision). My current lactate threshold is about 160. My tempo intervals this morning confirmed it to be around 158-162. Calling my LT heart rate = 160 seems fine for my purposes. Here are self-testing details and more options:

Matt Fitzgerald Self-Tests
Joe Friel Self-Test

Once you determine your lactate threshold heart rate, you can set training zones. Both Friel and Fitzgerald agree that aerobic training should not exceed 89% of LT HR. For me, that is HR=143. The other zones vary a bit between Friel and Fitzgerald. I'm using Fitzgerald's zones because they are a little simpler (see his training zone calculator in link below). My HR zones are:

Easy recovery: 117-129
Basic Aerobic: 130-143
Tempo: 153-160
VO2 max: 163+ (based more on perceived effort than HR)

According to Fitzgerald, in his 80/20 book and web site (with heart rate zone calculator), 80% or more of your weekly miles should be in the recovery or aerobic zones. Only 20% (or less) in the harder tempo and above zones. And you should avoid the middle "grey zone" between aerobic and tempo--not hard enough to stimulate real positive change, but too fast to allow full recovery. Train hard (20%) or easy (80%). No middle ground. For a full description of the 80/20 running plan, with rationale and example runs for each zone, see Matt Fitzgerald's excellent running book.