Hello TheEd,
From January of this year, I decided to start running more seriously.
I started with your sub 50 10k training plan.
In the past, I had a couple of runs here and there but not too often and without a training plan. Generally speaking, I'm a couch guy how wants to change a lifestyle finally. I'm male/31y old (173cm / 71kg).
My current PBs:
1K - 3:59 (probably could do 3:55)
5k - 23:59 (avg HR - 194)
10k - 49:50 (avg HR 183)
HM - 1:59:06 (avg HR 179, effort 8/10, I just wanted to test myself)
Volume since the beginning of the year:
January - Distance: 122.18 km / Time: 14:00:30
February - Distance: 171.87 km / Time: 19:46:10
March - Distance: 134.14 km / Time: 15:12:04
April - Distance: 206.83 km / Time: 23:21:20
May - Distance: 70.31 km / Time: 8:27:03
June - Distance: 102.62 km / Time: 11:28:07
Of course, after I increased weekly volume in April too quickly to 60km per week for 2 weeks in a row I got injury 
After HM I did not rest adequately but took just 1 day off and that cost me of knee bursitis (inner knee pain)
I'm trying to return to 5-6 days of the training regime and actually this is my first "official" week back after the injury so my focus is to build a base.
While I was off, I did Vo2max lab test so I could figure out my real HR zones.
I have 207bpm max HR (but I think this could be even 210) and as you can see I can hold 180 bpm during 2h run (HM).
Lab results:
Vo2max: 50.9
L1: 166 bpm (34,2 ml/kg/min)
L2: 180 bpm
The doctor said that I should keep my easy runs between 145 and 165bpm.
So my question is should I take my L2 as a base for my HR zone training?
This is what I would have if I go with L2:
Zone 1 - 117-143
Zone 2 - 144-159
Zone 3 - 160-170
Zone 4 - 171-179
Zone 5 - > 179
My current pace is 6:50-7:00km/min for easy runs. My current HR easy pace is around 140-149 depending on the weather. It's calculated by Garmin based on my max HR.
The thing is I can keep conversational pace while holding 150-155 bpm so I'm confused should I run faster on my easy runs or not?
I want to build a strong aerobic zone and keep improving (speed and distance) in running so any advice will be appreciated.
Thank you for your help!