Looking at my log, I know I've been doing too much anaerobic work. oops! Most of the time, I'm trying to stay at MAF + 10 or 15 on AE days, but there was one 5K I tried at a faster pace just to see what would happen. I thought I was going to die. I actually walked for about 30 seconds because my HR was so high, I wondered if it would just explode. Therein lies my question. After a person finishes the base phase, is i normal to hit a higher high HR? For example: Before MAF I ran a 9:30-9:45 pace with a HR of around 160-165. After MAF basebuilding and a month or so of very little AE work, I now hit nearly a HR of 185 at that pace! (I did warm up for 2 ish miles at below MAF) I have no clue how to interpret this. Is this a sign I should go back to full time basebuilding again or what? I have no running goals right now. I'm just kicking back, having fun until I start training again in ernest for a 1/2 in November. I'm not really into building up my mileage significantly at this point. I'm trying to add in more cross-training stuff for fun. I do intend to do a bit higher mileage than I have been, but I'm taking a break from 2+ hour runs. I find myself wondering what the h#ll I'm doing most of the time.

That makes sense, and probably something for me to look into for sure. It does make sense that I wouldn't be able to just run faster after not having done it for 12 weeks. I guess I'm wondering too, am I actually nearing death at that high HR. I'm nearly 36 for reference. It just seems like if I'm asking my heart to do that for an extended period of time (30 minutes or so), that just can't be good. I have no data to go back on. I don't know my Max HR and have not had a VO2 test. My garmin had my heart rate at over 100% of max!

Before MAF I ran a 9:30-9:45 pace with a HR of around 160-165. After MAF basebuilding and a month or so of very little AE work, I now hit nearly a HR of 185 at that pace! (I did warm up for 2 ish miles at below MAF) I have no clue how to interpret this. Is this a sign I should go back to full time basebuilding again or what?

To me the most obvious reasons would be that you didn't build your aerobic system during base building (maybe your MAF HR was too high) or you quickly lost it during that period of anaerobic training (which was not long so it makes me think you didn't have enough base). That's 20 beats higher at the same pace -- this is very significant. If it's accurate, it warrants further evaluation.

Maybe the question is 'when I have I done enough aerobic base work?' This is more useful to know as we all want to most amount of aerobic base since it gives us the most fat-burning, speed, health, etc. The MAF test or some equivalent is a great way to answer this question, as has been discussed in detail here. If almost all our energy needs during a race come from the aerobic system, why not build it up as much as possible. The obsession with speed work gets people in trouble more than anything else (the old phrase 'speed kills' still works).