When lactate threshold goes missing: Garmin Forerunner issues

Users of Garmin Forerunner watches have been frustrated by an on-going problem with lactate threshold. For the past few weeks, the detection of this crucial measure has not been functional.

It appears that the issue affects the majority of Forerunner timepieces, including the 265 and 965 that were just launched. Lactate threshold detection was working fine up until mid-January, but users complained that Garmin Connect was not updating the numbers. The problem was resolved briefly and both detection and uploading functioned well from the middle to the close of January. Since February both stopped.

Garmin is aware of the issue and is actively investigating the root cause. However, this is not a widespread issue. They’re currently working on determining why the functionality works for some people but not for others.

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There’s a massive thread on the Garmin Forerunner 955 forum discussing the ongoing problem. About a week ago, a Garmin moderator made a mistaken post claiming that firmware update 14.20 resolved the problem. However, this is untrue. The following was posted four days ago by another Garmin employee.

“SW14.20 has no relation to LTH. The agent you heard from was referring to something different, involving LTH and the Connect app that was resolved in a previous sw version. We have a different case going right now for this specifically, it is under investigation and has not been resolved yet. I’m sorry for the miscommunication.”

Why this is a important

The lactate threshold metric will be familiar to serious runners. It is an essential indicator of performance because one of the best indicators of success in endurance sports is the capacity to maintain exercise at or near the lactate threshold. By increasing the body’s ability to clear lactate, the muscle’s capacity to act as a buffer, and mitochondrial function, training at or just above the lactate threshold can enhance endurance capacity.

Garmin watches use a combination of heart rate data and GPS tracking to estimate a person’s lactate threshold. This is based on the relationship between heart rate and exercise intensity. If you wear a heart rate chest strap during your run and exert yourself sufficiently for an extended period of time, this is updated automatically.

The other option is to do a Garmin lactate threshold test. Usually, a user must warm up for 10 to 15 minutes at a leisurely pace before beginning the 20-minute time trial effort. The goal of the time trial is to maintain the highest sustainable pace. After the test is complete, the Garmin watch determines the user’s lactate threshold based on the heart rate during the exercise.

Once a user’s lactate threshold has been estimated or measured, Garmin watches use this information to set training zones. These can be based on heart rate, power, or pace. Depending on a user’s goals, the zones assist athletes in training at the proper intensity to increase their endurance, speed, or power. For instance, the Garmin watch can recommend training sessions that include intervals performed just above or below the lactate threshold to improve an athlete’s endurance capacity if their lactate threshold is known.

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