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Marathon Training: Respect the Heat


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I’m at the two week countdown to marathon day and my confidence heading into the race is at the lowest point that it has been this training cycle. My major goal for last week was to get in a final, solid 20+ mile training run. Well, I ran 20 miles last Tuesday, and it was far from solid. In fact, it bordered on disastrous.

I’ve never had a good experience in a Spring marathon. Boston 2011 left me in the med tent at the end, and both previous times I’ve run the Vermont City Marathon resulted in me hitting the wall hard around the big hill at mile 15. I think the reason is twofold. First, my training is typically lousy through the winter (due to work and weather) and I enter the marathon buildup with an inadequate base. Second, I start the training cycle in cool weather and finish it in the relative heat of late Spring. I’ve come to realize that I am really sensitive to the change in temperature, and I need quite a long acclimation period before I can handle running long in warmer weather.

The plan last Tuesday was to get out as earlier as possible since the forecast was calling for the warmest day of the year so far. Unfortunately the morning wound up being busier than expected and I didn’t leave the house until around 11:00 AM with temperatures nearing 80 degrees Fahrenheit. Being the stubborn runner that I am, I opted to go for it anyway and set out for the 21 mile run that Caleb had put on the schedule.

My legs have felt dead for a few weeks now, but I felt ok at the start of the run. Not great, just ok. Given that it was going to be warm, I opted to wear a hydration pack and bring along a few gels. I planned to stop back home at about the midpoint for some sports drink, and the first 12 miles were fairly uneventful aside from the fact that I was tired, hot, and getting really hungry. I stopped at the house around mile 12 and had half a peanut butter and jelly sandwich and some Powerade. Shortly after heading out again things started to go badly. Here’s how I described the run on dailymile:

“This one was a complete mess. I made the epically stupid decision to run at mid-day on one of the hottest days of the year so far here in NH. By mile 14 I was reduced to a walk-jog mess, but was determined to get in the full 20 (finished the run at an average 9:37 per mile pace). In retrospect I probably shouldn’t have pushed it because I think I ran myself into heat exhaustion. Started cramping in places I’ve never cramped before after I stopped (neck, abs…) so think it was salt/hydration related and not just neuromuscular fatigue. Cooled off in the kiddie pool with some cold water, cramping the entire time, and it was intensely painful. Had some salty bouillon on the couch and fell asleep for about an hour, felt better when I woke up. Need to work on strategies for running long in heat, don’t ever want to feel like this again. On a positive note, the Saucony Kinvara 4 worked well, my feet are about the only part of me that doesn’t hurt :)”

So yes, miles 14-20 were a total mess. I’m pretty sure the heat was the major factor. I was caked in salt by the end of the run, and the cramping was quite unlike anything I’ve experienced before. Bad day all around, and not how you want to head into your taper. I’ve taken it super easy over the past week so I don’t totally wreck myself, we’ll see what happens…

So now I’m left to figure out how to approach the race in two weeks. My original plan was to just go easy since I knew I’d be doing a rapid and inadequate buildup, but a really solid 18 miler several weeks back got me to thinking about pushing it a little harder. That may have been my big mistake as things started to fall apart shortly thereafter. Not sure if I pushed the training too hard too soon, or if the heat is the really big factor. Probably a bit of both.

I’ve come back around to just heading into the race with a plan to have as much fun as possible. That’s how I approached Disney back in 2010 and it was probably the most enjoyable race that I’ve run. I’m not shooting for a PR (that was never part of the plan) so there’s no point in running myself into the ground and dealing with an extra long recovery. If the forecast is hot on race day I’ll need to go really easy since it’s clear to me that I’m still not ready to run long in the warmer weather. I’ve solicited some advice on Facebook about using S-Caps or Salt Stick and I think I may give that a try.

I’m reminded once again that marathon training is hard, and I’m trying to figure out what to do in the Fall in terms of races. I don’t think I’ll be doing a road marathon. I had a blast training hard for the half-marathon last summer (I like shorter and faster better than longer and slower on the roads), but I’m also suffering a bit of peer-pressure about running the Vermont 50K in September. Decisions, decisions…

On an unrelated note, my blogging has been minimal the past few weeks since I’ve had to prioritize packing up my office and lab, and tying up loose ends at the day job. My contract is up at the end of this week, so expect a return to normal posting soon. Tons of reviews to get through!

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About Peter Larson

This post was authored by Peter Larson. Pete is a biology teacher, track/soccer coach, and dad (x3) with a passion for running, soccer, and science. If you'd like to learn a little bit more about who I am and what I do, click here, or visit


  1. Amanda Loudin says:

    There’s a reason i never sign up for May marathons…even with the fall races, I tend to stick to November b/c it is just a much surer bet. Heat and marathons just don’t mix for some of us!

  2. Andrew Bentley says:

    I found this really interesting as i’m also prone to bad experiences with heat acclimatization during spring and early summer.

    I wonder if running with a Heart Rate monitor could be beneficial to alleviate this issue during training to help the runner moderate their effort whilst adapting to the temperature and avoid overheating etc?

    If you know the HR that you can comfortably train at for a long run (for example) then so long as you don’t go over that figure for extended periods of the time you’ll stand a better chance of being ok. That’s what I’ve been trying to do this year anyway.

    On the hydration / electrolyte issue, I’ve found it interesting to follow what Prof. Tim Noakes has been saying on that subject recently….

    • Andrew Bentley says:

      This may be obvious from the comment above but forgot to add the point that the rationale behind wearing the monitor is that at the same pace, your HR will be higher in warmer temperatures

  3. RichFrantz says:

    I don’t know what the consensus is, but if it was me, I would do the rest of my taper runs at the hottest part of the day. They are by definition less taxing, so I would use the time for heat acclimation.

  4. Robert Osfield says:

    Tough sounding workout. Quite the opposite from a long hill race I completed ten days ago – gale force winds, freezing temperatures and sleet at the summits, and bogs so deep they swallowed a whole leg! Numerous runners ended up with exposure with two runners and a Marshal taken off to hospital!

    Getting used to heat is something you can do within a two week window, you’ll adapt to sweat more and loose less salts. All you need to do is exposure yourself to an hour or two of hot conditions for as many days as you can manage. You needn’t be running, just get hot, get sweating, replace the fluids and and let you’re body will do the rest.

    One thing I’ve done here is to spend some time in the Sauna at the local swimming pool when my kids are swimming. With a Sauna I can’t yet say in more than ten minutes on the trot, but I’m sure if I went more regularly I’d adapt.

    Being heat acclimatized will help your performance whether it’s hot or cold so either way you’ll win.

    Good luck with the taper.

  5. Chris Kilmer says:

    I’ve had PLENTY of days where I had an AWFUL run one day and then a PR the next.

    Don’t get flustered. It was a training run. Seems to me like you learned some good lessons. Let the experience boost your confidence on race day :-)

  6. April Pratt says:

    My dad and I have been using salt tabs for long runs for a few years now, they definitely are a must on warm days for me.

  7. Tim Dyches says:

    Worst run I ever had was a out and back trail run supposed to be a 17mile. Relied on a drinking fountain that was on the trail instead of carrying water. Major dehydration and heat stroke. Ended at 15 puking and laying on the ground. Good news is the next run was perfect. Good that you got this one out of the way.

  8. It seems like I’m always caked with salt after long runs. Decided to order endurolytes fizz from Hammer for the marathon next Sunday. I’m an idiot. I thought I could just pop them in my mouth, and they’d be a nice refreshing fizzy pick-me-up. Of course, when they arrived and I tried that, my mouth foamed up like Cujo. Ordered the S-Caps, which is what I should have done in the first place.

    • Pete Larson says:

      Nice! I probably would have done the same thing with the fizz :)

      Sent from my iPad

      • Tried the S-caps today. It was about 80 degrees, and I did 9 miles. Took one tablet with a half glass of water so I could get a sense of how it would make my stomach feel. About 20 min. into my run, starting getting major sloshing in my gut. I thought this was exactly the kind of thing the S-caps were supposed to prevent. What’s the deal? Not going to use them Sunday.

  9. SportsSignup says:

    It’s really amazing how much difference a few degrees can make for a runner. Not many other sports are so affected by temperature changes but then again they aren’t doing quite the same thing to their bodies as running 20 miles!

  10. Sarah @RunFarGirl says:

    The humidity on Saturday is what got me. I raced big-lake and had pretty solid training for a sub 1:45. But I was overdressed for the humidity and heat. At around mile 10 my legs were tingling–weird. Also cramping in my side, which doesn’t usually happen. And as soon as I stopped I had severe cramping. Needless to say I didn’t get the finish I wanted. I should have changed my race plan according to the temps. I’ve been running in the cool early mornings of 38-45 degrees. My body did not like the sudden change.

  11. Samuel Ho says:

    Do you think the horrible run would help with acclimatization or is it just suffering for suffering’s sake?

  12. Robert Youngren says:

    If you tend to wilt in the heat like I do, never been a good heat runner, then I strongly advise sauna training. I incorporated Arthur Webb’s heat training guide before Badwater a couple years ago and it made all the difference. Basically crank that baby up as hot as it will go and just sit in there with a bunch of ice and water. Build up to 45 minutes sessions over whatever time frame you have available but DON”T try and exercise in there. Since Badwater I don’t feel as affected by the heat and humidity near as much as I used to (that race changed me! Now I know what heat is!). But I still hit up the sauna for any upcoming event where heat may be a factor as I am still a lightweight in that department!

  13. packrats999 says:

    Speaking from personal experience, it’s possible you are starting your Spring training cycle in better shape than you are in the Fall. The temptation is to train too hard too soon in the Spring. As a result, there are too many “withdrawals from your account” rather than “deposits into.” I’ve met great runners who can train hard all the time. I’m not one of them. If I see a trend of too much “hard run/recovery run” accumulating in the cycle rather than enough boring daily distance, I will crash and burn at the end of the cycle.

    • Pete Larson says:

      Could very well be the case, was pushing hard when I was feeling good several weeks ago, may have overdone it.

  14. I have had (and continue to have) similar experiences w/ spring training. One thing that you did not mention is teaching. I’m a high school teacher and I’m done, both physically and mentally this time of year. When I look back on my journals, May is usually a disaster. I just got over a bad 2 weeks, took time off and now things are looking up. I almost registered for VCM back in January, glad I didn’t . I have decided on Boston for 2014, but for me I can handle winter better than spring. Best of luck.

  15. There’s always a transition from winter to spring to summer training. Especially here in MN where our winters are long. 60 degrees now feels a lot warmer then it will come September!

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