Be careful in the heat

Today I had a 10 mile run on tap with 6 at tempo on a rolling hills section of my town.  Last week I did very well on this run, with paces a little faster than the goal.  I felt strong and solid on the run.

The weather last week was overcast and 9 degrees cooler than today, and humidity was slightly lower than today.

Today was a different story. 73 degrees F when I left the house at 6 AM and 92% humidity.  By the time I reach 2.5 miles in the run (the end of my warm up before my tempo– 6 miles at 7:37 pace, my goal marathon pace), there wasn’t a dry piece of clothing on me and my HR was creeping up a bit.

I started at my usual spot for the tempo miles (I do so each week so I can run the same course and compare from week to week).  The first two miles were at, or just below, goal pace.  But as I ended mile 2, my HR was into the 160s, which is what it normally would be by mile 18 of a marathon, NOT mile 4 of a training run.

Everything began to fall apart as I pushed harder uphill and my HR spiked near 170, which is danger zone for me.  Too high and I risk damage rather than gain.  Prevailing thought in marathon training now is that training at a level too intense risks longer recovery time for the next run. In short, don’t blow up on your training runs as you will place at risk future runs.  Recovery time from a run where you go too hard for too long is much longer than one where you stay pace or HR disciplined.  It can create a cascading effect where you struggle to regain strength for longer than necessary after pushing too hard.  In short, don’t be a hero.

My HR spiked and as my body struggled to cool itself, it took a toll on my legs (circulation now focuses on cooling the body core temp and not sending blood to the legs), and heavy fatigue set in, as I found myself struggling to get deep breaths.  At mile 4 I changed the Garmin screen to show HR only.  I ran by that.  If HR creeped into the higher than the mid-to-high 150s, I eased back.  I honestly don’t remember miles 5-8. The rest of the run was a death march back to the house.  My last mile, a cool down mile, was a minute slower than normal, yet the HR was 15 beats a minute HIGHER than normal.  I went out too fast, as if I was running in ideal conditions.  This dug a hole from which I couldn’t escape.  Had I started slower and let HR build slowly to my normal tempo number, then I would’ve not struggled so much.  The irony is that I’ve had a pretty solid summer of running so far, but the heavy killer heat and humidity is beginning to descend upon us here.  Milder conditions in the past few weeks led me to a false sense of security and confidence about maintaing goal pace in this junk.  Today was a major slap down, and a realization that to get what I need out of my  training this summer, I need to be careful, scale back my paces, and run my HR on long and tempo runs.

What did I learn, that I already knew and should have realized before setting out to run? Summer in Alabama requires running by HR, not pace.  I know what my HR should be on certain types of run.  Late in marathons my HR should be mid-160s.  On zone 2 (easy) runs, it should range from 130-140.  on tempo runs such as today it should be nor higher than 158 or so at the hardest point. DO NOT wait for the body to get into alarm mode to adapt your training.  I did that today and paid the price.  You will receive the same benefit from training at marathon pace HR or effort in hot/humid conditions as you will by training at goal pace in ideal conditions.

This is a great link for thoughts on Heat running.

(There has been a lot said about the Central Governor and us forcing a little more control over it, but there are times when the Central governor is right to slow us down. Running in extreme conditions is one of those times)

The silver lining to this is that as crappy as we feel running in hot/humid conditions those feelings are NOT a true indication of our true fitness.  Once the temps cool and humidity drops a bit in the early fall I will feel like super man.  It happens every year.  And yet I still struggle with the feelings of loss fitness or losing ground on a marathon goal in this heat.   Sometimes running smart take more strength than running fast.


  1. I wish I would have read this before my similar run yesterday. Although I did adjust slightly I also went out a little too fast (St. Louis is also hot and humid), What I didn’t know was that my recovery would take longer even though it makes perfect sense.
    Thanks for the advice and reminder to adjust to the heat.

  2. With a group of youngsters, you can do six to eight runs of 45 seconds, followed by some 10 second sprints on a steeper hill. With top class senior runners, you can do 12 to 15 runs of about 70 seconds, so that it is the equivalent of an interval training session on the track. A good practice is to increase the number by one or two each time the session comes around, while trying to run them at about the same pace. The recovery is a slow jog back to the bottom, and when the times start falling much below those of the first few runs, it is time to stop.

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