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Why doesn't heat acclimation use temperature from the device sensor?

silentvoyager
over 2 years ago

I know the device measured temperature is affected by the body heat, but the effect is strong only when the outside temperature is low. When it warm enough for heat to have effect on performance, I'd argue that the influence of the body heat on the device measured temperature would be small to minimal and perhaps the algorithm could be calibrated to take the device temperature as opposed to the weather data.

Consider the following temperature graph from a recent trail run in Grand Canyon:

Despite device temperature reaching 99°F at the peak, this run didn't produce any heat acclimation effect. None! Furthermore, my VO2MAX dropped by 2 points after this run, although later it quickly recovered back to the previous level. That indicates that the VO2MAX algorithm didn't take the temperature into the account either. 

The temperature at the start of the run was 37°F according to the weather forecast. That is because we started at the top of the rim. But as we descended the temperature quickly raised and was unbearable in the afternoon.

I can imagine other similar cases. Any mountain activity with a lot of elevation change could involve an equally wide range of temperatures where the weather can be balmy at the bottom but chilly at the top. So a temperature from weather data would be equally unreliable. 

  • 0 over 2 years ago

    Humidity also feeds the Acclimation algorithm.  That's why the weather data at your location is used to adjust the acclimation software:

    https://www.garmin.com/en-US/garmin-technology/running-science/physiological-measurements/heat-and-altitude-acclimation/

  • 0 over 2 years ago in reply to Dan.Boilermaker

    Air humidity doesn't vary as much as the temperature. 

    In any case, it isn't clear if the algorithm considers the entire temperature range during an activity, if it takes a long time, rather than just the temperature at the start. 

    The reason I think that way is because it shows 37 degrees as the weather data for the run in Garmin Connect:

  • 0 over 2 years ago in reply to silentvoyager
    silentvoyager said:
    The reason I think that way is because it shows 37 degrees as the weather data for the run in Garmin Connect:

    I think you are correct about the start temp.  This situation is certainly not the norm.

    Off topic, but I truly love going down into the canyon.  Such a different world from what you see from the Rims.  Looks like you turned around near Cottonwood?

  • 0 over 2 years ago in reply to Dan.Boilermaker
    Dan.Boilermaker said:
    Looks like you turned around near Cottonwood

    Yes, unfortunately the trail to North Rim was washed out and closed for all traffic by the park services. The original plan was to do R2R2R.

    I should add that I was disappointed by how many watch issues I'd run into. The satellite tracking with multi-frequency GPS worked quite well even in the narrow canyons, which was impressive, but a lot of other things had glitched. It feels like nobody in Garmin has ever tested the watch on a route like this. All the issues are so obvious! Some of those issues I've reported a long time ago.

  • 0 over 2 years ago in reply to silentvoyager

    Nice.  Hope you get another chance.  NR down to Cottonwood is my favorite section.  I'm amazed by the amount of vegetation that surrounds Bright Angel Creek.

  • 0 over 2 years ago
    silentvoyager said:
    Despite device temperature reaching 99°F at the peak, this run didn't produce any heat acclimation effect. None!

    From my POV, acclimation is the long-term adaptation of the body to changes in environmental conditions, which usually takes 1-2 weeks. It is not about the change in temperature or altitude during an activity. Therefore, acclimation is not considered during an activity. So I don't think temperature or altitude play an important role, but only serve as triggers that environmental conditions have changed and acclimation needs to be initiated. Using the temperature sensor in the watch doesn't help in this case.

     

    silentvoyager said:
    Furthermore, my VO2MAX dropped by 2 points after this run, although later it quickly recovered back to the previous level. That indicates that the VO2MAX algorithm didn't take the temperature into the account either. 

    VO2max is calculated based on the relationship between HR and speed. When running in the heat or uphill, HR is higher than usual or speed is lower than usual. Since the estimation model doesn't take heat or hills into account, VO2max decreases. When running for the first time in new conditions, this can be considered an outlier and smoothed out, but when running more often, VO2max stabilizes to the new value over time. If the deviation of the last activities is sufficiently small, acclimation is achieved.

  • 0 over 2 years ago in reply to subra

    Not according to this Garmin article: https://support.garmin.com/en-US/?faq=PQCtbgWxJ65nRatXoHCmy7

    It states that "Compatible watches and cycling computers provide acclimation notifications and corrections to your recorded VO2 Max Estimate and Training Status when the outside temperature is above 22ºC (72ºF)".

  • 0 over 2 years ago in reply to silentvoyager

    What the article does not mention is that they only seem to take account the temperature at the start of your ride/run. I stay in South Africa and often get into the situation where I start early and temp is 20. Half an hour later it is 25 and you spend 5 hours in the heat thereafter. Zero heat acclimatisation. Go for a quick 30 min recovery run after work and your acclimitisation pops up severely. 

    But truth be told, the acclimatisation happened, whether Garmin says so or not! But fully agree that, if not the temp sensor, at least the entire ride's temp should be considered. 

  • 0 over 1 year ago

    Yes, Garmin's algorithm for heat acclimation is severely lacking, to the point of just being a gimmick.   It just seems to use one temperature point (the starting temp) as the basis for the full activity.   My longer rides, with a lot of heat exposure (summer in Texas), don't register because I start early.  Come on Garmin, you can do better!

  • 0 over 1 year ago in reply to norwaysheley
    norwaysheley said:
    My longer rides, with a lot of heat exposure (summer in Texas), don't register because I start early.  Come on Garmin, you can do better!

    I recommend suggesting it to Garmin at Share Ideas | Garmin. In the meantime, there are two possible workarounds: 

    1. Use the Multisport / Change Sport feature. When the temperature rises, use the Change Sport function, and start the same activity type again. The temperature for the acclimation will be re-acquired from the watche's Weather Widget data.
    2. This one is not tested, but could perhaps work too - pause the activity, using the feature "Resume Later", and then start it again (you do not need to wait, just start it after you paused). Typically all the activity initialization happens during the activity resuming, so there is a good chance the temperature gets reread again.

    As to the request in the OP  - the internal sensor cannot be used, because it does not measure the ambient temperature. The internal temperature depends on many factors (body heat, sun exposure, moisture, wind, cover, ...), and does not really reflect the ambient temperature much, unless you keep it off the body and in a shadow, or unless the watch is underwater (due to the 24 times higher thermal conductivity of water).

    I have plenty of winter activities where the internal sensor shows temperatures above 30°C, despite freezing air temperatures (it is enough to have the watch under a sleeve). The Heat Acclimation algorithm kicks in already at 22°C

    Also please note, that the temperature shown on the map of the activity is not necessarily the same as used by the watch for the acclimation. What is important is the temperature shown by your Weather Widget on the watch. The temperature on the map comes from a different data source (I have tested it many times), and it is often significantly different.