Well sometimes we need adjustments above and beyond the T+D. Did the run feel like LR effort in the beginning?
So the HR average was 152 (within range), but by mile 7 of 12 you were climbing into the 160s? It seems like your first run your first 5-6 miles were in the 141-144 range vs this run during the same long run portion you were in the 145-150 range. Was the effort higher as well between two weeks ago and today? Your EA and EB runs show consistent HR from beginning to end with no change in effort. So would you agree you're seeing something different in these long runs? Despite no change in effort an increase in HR occurs. So not the case of gradual HR increases across all types of runs.
I also notice a lot of dropouts in your HR. Are you pausing the watch, and if so why, or is it a case of the watch dropping out? How long are those pauses lasting? Is this something you've been doing for awhile or only recently?
Yes, the 12-miler felt like a LR in the first half. Not hard, easy breathing. I agree with your assessment that the HR seems to increase for no good reason - except that I am not conditioned, I assume.
The run is an out-and-back, so the biggest drop-out in the middle is when I paused to turn around. I generally stop for about 3 minutes when the watch gives me the recovery HR info. This time, since I had planned to eat my last sport beans at 6 miles, I stopped until I ate those, which was about 5 minutes.
I have other drop-outs for pausing for several traffic light street crossings - sometimes I get lucky and get the walk sign right away and sometimes not. I did take a maybe 1-min break on each half-mile in the last few miles because I was not doing well. I generally do not take extra breaks unless I am starting to do really badly, and then it's to help me recover and be able to complete the run. I have to get back to my car!
I don't know of anything that changed when I hit my turn-around point and start coming back. In fact, the return direction is generally downhill, so it should be a bit easier. (I am applying a GAP adjustment.) For this specific run, mile 6 (and the return mile 7) have two short but very steep hills in them (that you get both ways). I took them pretty well in mile 6 and didn't get extra winded, but didn't judge so well in mile 7 and was really sucking wind after them.
So only 34 grams carbs per hr in both runs. One time with 100% liquid source and the other time with 100% solid source. I'd try experimenting with what your maximum can be. See if you can tolerate more especially early on. Like I said elsewhere, I seem to do best at 75g or more. I'm at 93 grams per hr at this point in time.
I will have to try it. I really am not sure they will get through my digestive system. I have very slow stomach emptying - a fun fact I learned some years ago when I had a tracer followed through my digestive tract for a now-resolved issue.
One other point. When I get to the point where I'm feeling very badly - heavy breathing and high HR - I also often feel "weird" in the abdominal area. Not side stitches or nausea. Maybe bloating is the best word for it - very low, below the belly button. It sometimes feels like the waistband of my shorts is too tight, which is why I settle on bloating - so sometimes I roll the waistband down a bit. This gives some immediate relief, but not for more than a few minutes. However, I don't really pass any gas, so maybe not bloating. It really makes me feel like I don't want to put anything more in my stomach, although I will generally do so anyway for hydration, at least. Just weird. And I don't know if this is a cause or effect.
, 4.5% correction
