7/5 run 59 mins (4x1200m) @ ATT soft side in New Balance MT10 Trail Minimus
1. 6:26 HR avg 166
2. 6:33 HR avg 173
3. 6:39 HR avg 174
4. 7:03 HR avg 174
temp 85+ (about 7pm start)
HR avg 157 max 180 (average heart rate includes 10 min warm-up, 10 min cool-down and 400m rest intervals)
I think these times give a pretty clear picture of what the heat does to my performance over time. I've started walking all my rest intervals in the heat as my heart rate never drops below 135 anyway. It's interesting to look at how my heart rate during my 400m rest intervals creeps upward from interval to interval. I think this is just a result of my body trying to cool itself. I went back and looked at some of my speed work data from the cooler months and it seems I was able to recover consistently between intervals, so it definitely looks like it's the heat/humidity that's getting me.