Tag Archives: heat acclimation

Checking in 6/22/2021

Yesterday I woke up later than usual, and skipped my planned fast finish run before work that morning.

I decided I would try and run it after work, something I hadn’t done since early spring. Obviously, the heat is a key reason I avoided late afternoon runs, but also I had been wary of a late day run’s effect on my sleep. That said, my sleep hasn’t been what I’m looking for this last month (my waking up late yesterday is a product of that), and so I had a lot less to lose trying a late workout yesterday. Worst case scenario, I’m not drifting off to sleep until later in the evening, which I’ve already been doing.

I also decided I’d try another avoided tactic: I would do the whole workout on the treadmill at the gym. I generally have a hard time with the old treadmill not just because of the relative monotony, but also because with no wind resistance I can get hot fairly quickly at room temperature.

(An aside: Room temperature and humidity are actually fairly hot conditions for a run, typically around 73-76°F (23-24°C) and 30-40% humidity. At my mild pace and weight, my perceived temperature was around 101°F, 38°C. If I had run the same in typical warm Chicago conditions, say 70°F with 50% humidity, the perceived temp would only be 97°F, 36°C. While I haven’t written any pieces about this, room temperature’s perceived heat index for runners is a legit issue with using the treadmill, and again remember there’s no wind indoors to provide any sort of breeze.)

I had a triple whammy surprise waiting for me after work, on top of still feeling a bit tired and sore from the weekend’s many workouts. I had brought my running shorts to change into, but I forgot to bring my fanny pack, in which I always carry my keys/phone/IDs since while the shorts have pockets they can’t handle the weight of all the above. Also, I will lose things I put down in public, so carrying them in my hands is not a practical solution.

So, to do the treadmill workout, I’d have to do it in my slacks with my keys/phone/ID in my pockets, just like the work break runs. Fine for a 10-15 minute break jog, but a full 30 minute treadmill workout?

Recall that I now use a Stryd footpod, and one of its many benefits is it calculates accurate running stats (pace and power) on the treadmill. The Stryd even indicates how much a given treadmill’s displayed pace is miscalculated. I have found the Stryd rather accurate, and it often shows within 0.02-0.03 miles (40ish meters) of the treadmill’s stated distance, whereas my Garmin’s distance/pace estimates were never close.

I mention this actually because I could do this workout not by heart rate but by power readings from the Stryd. As long as a given treadmill pace got me to my desired Zone 1-5 power ranges, I could run steady at those paces. I find the needed pace is often slower than I would previously run on the treadmill.

Sure enough, I found my needed power range at an easy pace and cruised there comfortably. On top of that, and maybe the air conditioning was really strong, but the whole run felt super comfortable! Only towards the end as the sweat and body heat began to accumulate did I feel all that uncomfortable. Even the surge into the fast finish during the workout’s last 5 minutes didn’t feel unduly challenging.

Whether it was heat acclimation from running outside so much, whether the A/C was blasting real strong yesterday in the gym, whether my reliance on accurate power data led me not to push as hard as before… instead of the treadmill run being painful, hot, a struggle, the workout felt do-able, and my effort felt consistent.

I could now actually see myself doing most of my midweek training runs, and maybe even with some adjustments the long runs as well, on the treadmill this summer. As long as I’m still taking work break jogs, I’ll still get heat acclimation exposure during exercise (I obviously won’t stop taking those jogs) so I won’t lose those adaptions. Plus, the 70-75°F 30-40% conditions indoors are a better prep environment for the potential Indy Monumental conditions (likely 50-60°F, 13-18°C, with 70-80% humidity) than the dry and hot Vegas air.

Also, regarding the evening workout and my sleep being affected: I drifted off around 9:30pm, consistent with my recent patterns, and I slept a good 8 hours before waking around 5:30am this morning. So I think my sleep patterns can work with these evening training sessions, provided they’re not unduly difficult.

Also, while a slightly separate subject, minimizing AM training may be beneficial for my recovery since morning workouts tend to produce high stress levels and minimal heart rate variability throughout the rest of the day. If I don’t work out in the morning, my HRV stays balanced and my overall stress in the morning stays low.

So okay, Treadmill, I think I can work with you now.

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Heat Acclimation and Blood Volume In Running

One of the subjects Jonathan Savage (the FellRNR running guy) discusses at length is heat acclimation training, where you train specifically in hot conditions to either prepare yourself to race in hot conditions or to successfully race in less extreme, even more normal temperatures.

This is of course amusing to me as we in Las Vegas (and most of the United States, admittedly) are currently suffering through a bout of extreme heat. And in Vegas, we’re used to high heat, with summer days topping 100° Fahrenheit (38° Celsius), but the 110-120°F heat we have now is even above our typical pay grade.

Thus, those of us who run in Vegas get to practice heat acclimation training whether we want to or not!

Of course, Savage refers mainly to winter training for a spring marathon. In the winter temperatures fall below freezing in most parts of the country. If eventually you have to run a marathon in 60-80°F weather (15-25°C), you’re going to get hit hard by relatively warm conditions, even though you’d love to have those conditions in the middle of August. Your body will have acclimated to the other extreme of those cold conditions.

On top of that, Savage typically runs ultra-marathons in more extreme conditions like the hot and dry Badwater 135 race. So he’s not just dealing with a slightly warm marathon in London or Boston. He’s dealing with potentially 100°F heat with doubly dehydrating dry conditions. So even if it’s negative celsius or fahrenheit outside he needs to bundle up to prepare for running in 100°F weather.

Now, all that said, just because you or I have no intention of attempting such a race coming out of winter doesn’t mean that heat acclimation isn’t valuable.

Even with no races on the horizon, running in summer heat and the resulting heat acclimation (within healthy reason: Don’t go taking extended runs once the temperatures are over 100° without an abundance of cooling resources and support)… has one additional key benefit.

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