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How Does Garmin Measure Your Heat & Altitude Acclimation?

By Jiri Kaloc

Are you planning a cycling holiday somewhere warm and mountainous? Cycling in harsh conditions like high altitude and heat feels a lot harder at first. Your Garmin can help you understand how quickly your body adapts to these environmental factors. Let’s review how to read these features correctly.

When you first arrive at a significantly higher elevation or significantly warmer climate than you are used to, your performance takes a hit. It feels harder to push the same watts and you get tired quicker. But as you spend more time and complete more training hours in that environment, your body adapts and you will get back to your normal. This process is called acclimation and Garmin came up with a way to track it for you.

Heat acclimation

Garmin starts tracking your heat acclimation when the outside temperature is above 22°C. For most of us, this happens during summer rides, on vacation, and in training camps. Your device has to be connected to your phone to get accurate weather data in order for this functionality to work properly. Even if your device is able to directly measure temperature, heat acclimation is always calculated based on weather. Also, note that heat acclimation is exclusive to GPS activities.

  • Heat acclimation shows as a scale of 0 – 100% of how well you are adjusting to heat during training.
  • Full acclimation takes a minimum of four training days.
  • Non-training days have no effect, so you don’t need to train in heat four days in a row.
  • Heat acclimation will begin to decay after three days of no heat exposure training.
  • After about one month away from heat exposure, your heat tolerance will return to baseline.

You can use heat acclimation data from your Garmin to better pace yourself. If you’re seeing low percentages of heat acclimation, it’s better to plan shorter or easier rides. If you’re planning to break a PR or go for a Strava segment, make sure you’re 100% acclimated for a given temperature.

Altitude adaptation

Your Garmin device will start offering acclimation notifications when the altitude is more than 800 m above sea level. Most of us will only experience this when cycling or hiking in the mountains. It typically takes about 21 days to gradually acclimatise to a higher altitude. Your Garmin allows you to watch your progress. For example, let’s say you go to the Alps for a cycling vacation and ride at 3,000 m of elevation every day. On day five, your Garmin will show that you’re fully acclimatised to an altitude of 2,000 m.

  • Altitude acclimation shows you the number of elevation meters you’re fully adapted to.
  • The minimum and maximum acclimation values are 800 m and 4,000 m.
  • After about 21-28 days back to your regular altitude, you will lose all of the altitude adaptations.
  • For most accurate results, make sure your Garmin device is synced with your phone daily. This will allow your device to check your living altitude level and keep it up to date.

Training at altitude can be very beneficial for cycling performance, which is why most pros have their training camps at altitude. If you want to learn more about the impacts of altitude training on your physiology, check out our previous article.

Your VO2max and Training Status are more accurate

You may feel much less fit during a really hot ride and you might need a break to catch your breath in the mountains, but this doesn’t mean that your training isn’t productive. Without the acclimation features active, you would likely see a drop in VO2max. The heat and altitude acclimation features allow your Garmin device to take these environmental effects into account and accurately calculate your VO2Max and Training Status.