Great to see some newbies to the thread, the more the merrier.
Chickadee, you have decided that your baseline running will be 75% of MHR (some say 70% but I think 75% is more realistic and indeed comfortable). Therefore in your first 6 weeks (or 5 if you wish) you do all your running at 136 or lower (average for the run), but not running at 150 for 80% of the time and then walking the last 20% to get a 136 AHR).
Phase 2 is when you look to put a couple of sessions, preferably longer runs, in at the next step up which will be 145-150 AHR but keeping the rest of the runs at 136AHR .
When I did my HADD test (week 1 of phase1) then I could not get to 150 and my AHR for that 2400m was 137 with a max of about 145.
As far as what to do in phase 1 then it really depends on what you are after. I wanted to use the easy running as a means of building up the base mileage and remember HADD is a foundation approach, not race specific speed work. I have done some double days, got my long run in but only ran between 5-6 days ever week. My totals for the 12 week period finishing yesterday which incorporated normal training and HADD Phase 1 is as follows
Normal 6 weeks Total 132 Average 22 longest run of 8 milestwice in that period
Hadd Ph 1 Total 223 Average 37 longest run13.5 miles (yesterday) and many over 8 miles.
Bluenose, looking for to seeing your Hadd test results. I am now starting phase 2 and will be doing a test tomorrow or Wednesday. I don't particularly anticipate any earth shattering news but as you can see from the figures above, I am pleased that my foundation work has improved and that is solely down to me doing HADD otherwise I would not have had the motivation and I would have been too tired to do some of the runs I have done if done at my normal pace.
CW, I reckon you should be doing base running at more like 135 than 140 average but that can be adjusted. As you get into it it does become easier to keep the same pace but at a lower HR