That heat index is getting up into the range where I would just suck it up and go running in the morning. I hope you're recovering and drinking a lot of water.
Thanks for the sentiments, I am feeling pretty good now. This happened in the morning (at least for me); I started just before 9. Starting an hour earlier would have definitely been smarter. To make me seem slightly more sane, I did run with a camelbak (and nearly became an accidental drowning by breathing while drinking :)
Working on getting my runs into more distinct pace/effort levels has the beneficial effect that long runs are not so draining but I think that they do seem to be providing decent endurance training. [n.b. The origin for this approach is that I felt trapped in a local minimum where I wasn't getting much from my runs and feeling like, when I needed to run, that I was sliding backwards. Jury's still out, we'll see how fall goes]
I've been trying to keep HR in zone 2 (< 130) for easy and long runs which usually translates to an 8:30-9:00 pace. I started at 6am Saturday morning, similar conditions. At mile 14, HR was 140+ at a 9:15-9:30 pace on a pancake-flat stretch of trail, in the shade. Consumed 80+ oz fluids during the run, another 100+ in the 3 hours after. Was still down 2 lbs when I went to bed that night.
I am finding it nearly impossible to stay <130. Maybe it is my fitness level but there seem to be three low "plateaus" around 125, 137 and 142 bpm. In long runs and good weather, I can spend a good bit of time at 137 and late in the runs it creeps up and I can usually stay at 142. Maintaining around 125 bpm for an extended period of time, I feel like my coordination just is a mess and I loose all form. I am hoping that if I can do long runs this way frequently enough, I may be able to move toward 130.
But to your point, hot, dehydrating, yuck! Loosing 4-5 pounds during a run really sucks the life from the rest of your day.
Definitely sucks the life out, but it sure helps to pound the fluids. I've been using NUUN tabs. Drop one in each of my 20 oz bottles during and then alternate diluted apple juice and water with NUUN tab in a giant glass after. Salty food too.
Depends on your zones, those plateaus might be totally reasonable and 125 might be too slow a pace for you. Anything 119 and below would be a recovery pace for me and starts to feel pretty sloppy form-wise. My max HR is about 176-180.
My racing partner has a super high HR compared to me. His max is like 220, so his easy runs are in the 140's and 150's.