Garmin drops heart strap need for Lactate Threshold tracking

Garmin has released firmware update 21.14 a few days ago for its Forerunner series, including the 165, 265, 955, and 965 models. This brings a big improvement to how runners can track their lactate threshold measurements.

Lactate threshold, a crucial metric for endurance athletes, represents the highest intensity level at which a person can maintain steady-state exercise. Above this point, the body transitions from primarily using oxygen for energy to relying more heavily on anaerobic processes, leading to increased lactate production in the muscles. For example, my lactate threshold is estimated by Garmin at 161bpm. Above that I will struggle to maintain the same running pace and will need to slow down after a while.

The change-log of firmware 21.14 describes the new feature as follows: Lactate Threshold estimates are applied automatically after training with heart rate.

Now that statement doesn’t bring a lot of clarity as to what the improved functionality actually consists of. Luckily, this was further explained by a Garmin employee on the company’s official forums.


No more need for a heart-rate chest strap

The big change is that new firmware eliminates the previous requirement of wearing a chest heart rate strap and performing a guided test to determine lactate threshold. Instead, runners can now capture this data using just their watch’s built-in optical heart rate sensor during regular outdoor runs. The update maintains accuracy while making the feature more accessible.

To access this improved functionality, users need only maintain an established VO2 Max estimate and ensure they’re using GPS-enabled outdoor running profiles such as Run or Trail Run. The lactate threshold auto-detection feature, enabled by default, handles the rest during regular training sessions.

Essential reading: Aerobic and anaerobic training with wearables, what you should know

For those preferring manual control, Garmin has retained the option to input lactate threshold readings directly through the watch’s user profile under heart rate zones. However, choosing this manual route will disable the auto-detection feature.

Now this is an early Beta which has kickstarted the Q4 firmware release cycle for these Forerunner watches. So the feature may still be work in progress.

Garmin says, “If the results you are seeing after activities looks incorrect, we definitely want to investigate. Please respond with permission for us to view your Connect account and to reach out via email.”

The firmware update is currently rolling out. You need to be enrolled in the Beta programme, and initiate the download manually from your watch. Or simply wait until it gets to public release.

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Ivan Jovin

Ivan has been a tech journalist for over 7 years now, covering all kinds of technology issues. He is the guy who gets to dive deep into the latest wearable tech news.

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