Heat acclimation - just turn the fan off?

If I read the abstract correctly, it suggests the device is reliable but lacking validity (at least by their predetermined definition). Meaning it hits the same spot with repeated measures but that spot is off the “bullseye”. Granted, one might question whether the gold standard or definition of validity is overly stringent for a different application. Am I misreading?

This is my understanding, as well.

My main concern is that the validity is particularily poor at higher temperatures. They conclude:

In particular, care should be taken when assessing/monitoring higher Tc (above 39.5 °C) associated with heat-related medical problems, since the CORE sensor underestimates such elevated core body temperatures.

My main intention for getting such a device would be to ensure that I don’t overheat. I’ve already suffered a heat stroke once, not funny. And this is the area where the sensor seems to fail (somehow). If it was a sensor for 50 bugs or so I wouldn’t mind so much, but at this price tag I’m not willing to be a beta tester again.

However, I see great potential for these things. Just got back from vacation in South Europe. Here in Central-Europe we’ve had winter for the last 1.5 years. Riding at 34°C for the first time after such a long time was massively shocking. If you have an A race in July or August in a normal year (not this year) it may make sense to go through a heat acclimaisation phase first. I’ve already suffered so often under these conditions in my important races. And appears to be fairly easy to get the heat adaptions.

Coaches are always trying to build a body of experience ahead of the science. ‘Proving’ something takes a long time and by that time the experts already ‘know’ how it works for the most part. Both sides are important.

This post makes me miss the “good old days of the podcast”, with stories about the coaches installing saunas and riding in their steamy bathrooms. :smiley:

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Wow. I can totally understand wanting a method to monitor heat stress - in addition to symptoms which will be nonspecific with exertional stress. I expect the trend would still be of value even if not directly equal to core temp. Similar to EtCO2 and PaCO2 relationships. After all many monitors have significant margins of error - pulse ox, lactate meters, blood glucose etc. take good care of your health, cheers

That is troubling, and I agree that it would stop me from buying such a device.

Yes, especially if its humid. I’m fortunate to get heat training ‘for free’ in California. Our area has summer weather is hot and dry like in Cordova/Granada/Seville Spain.

Living in an area like this, the protocol is quite simple. After 2-3 weeks of riding in the heat, under reduced power, I’m able to ride at full or nearly full power except when temps are above 35C. However that isn’t true for everyone - a few months ago a 22 year old set power PRs and Strava KOM on Wednesday night worlds when it was 39C outside (and he had a couple 39 and 55+ year olds right behind him!). As for myself, that includes doing sweet spot intervals at 28-34C, and vo2/anaerobic intervals. I’ve done plenty of intervals on the trainer in a 28C garage with two fans, one pointed at the back of my head and the other pulling in 35-38C hot outside air in and directed at my chest.

I definitely learned to monitor signs of overheating. I’m not sure how I would approach heat training if living in a cooler climate. :thinking: I’d probably buy a sauna and spend evenings in it.

Check out Evie Richards Toyko prep stuff

She setup a cheap plastic greenhouse in the garage, with the trainer setup inside it, with a small electric heater going inside the greenhouse. Didnt win at Toyko but in the form of her life for the XCC/XCO World Champs a few weeks later

I’ve actually been wondering if athletes were passing out in hot baths or saunas after heat training.

When on vacation I usually notice this acclimatisation after 2 or 3 rides in the heat. I read somewhere that 70% of the heat adaption occurs after the first few rides. So I guess just riding under these conditions will already bring a lot.

The special allure for me are my two A races in July and August. Last year the August race was in brutal hot conditions. This was so tough. Now with Tokyo one could read a lot about this acclimatisation and it seems pretty straight forward. For 10-14 days hop on the indoor trainer after a regular ride sweat for 30-45minutes. Low intensity seems to be enough. Seems to be sufficient. That’s a pretty low hanging fruit for me given the watts lost when not used to heat.

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Maybe I’m a slow responder, it definitely takes me 2-3 weeks via training outside in the heat. There is definitely a quick response during the first week but it’s not enough to allow regular training in the heat.


So if the CORE body sensor is unreliable at higher temperatures - is it any better than taking temperature orally?

Or to put it another way, can I just use a sufficiently accurate oral thermometer?

At the start of this year Garmin seem to have introduced a heat acclimation stat I’m no idea how good it is though. What’s folks experience?

I’m guessing that this is from fancy head units?

Not supported on my device. Sad times. What Is the Heat and Altitude Performance Acclimation Feature? | Garmin Support

On bike head units the heat and altitude acclimation features rolled out to the 530 and 830 in April 2019 (not sure when on 1030). Earlier on some Garmin watches.

Gives a reasonable estimate but not individualized and ultimately comes down to paying attention to your body.

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