How Is Lactate Threshold Measured by My Garmin Watch?

Lactate threshold is the point where your muscles start to rapidly fatigue. Your device measures your lactate threshold level using heart rate and pace. When exceeding the threshold, fatigue starts to increase at an accelerating rate. Knowing your lactate threshold can help you determine how hard to train or when to push yourself during a race.

For more information, see our Garmin Technology page on Lactate Threshold. 

What Are the Requirements for My Watch to Detect Lactate Threshold?

NOTE: Many newer devices will no longer have the same requirements or options as listed below. For more information see: Improved Lactate Threshold Measurement Feature.

Your device can detect a lactate threshold through a guided test or auto detection when the requirements below are met. Not every running activity or guided test will provide an update.

• Compatible watch: To see if your watch supports a lactate threshold estimate, see “Lactate Threshold” in your owner's manual. 

• A chest strap heart rate monitor.

  • For best results, it is recommended to use a Garmin® branded chest strap heart rate monitor.

• An established Run VO2 max estimate must be set.

• An outdoor GPS enabled run activity profile, such as Run or Trail Run.

An accurate maximum heart rate setting is also required to obtain an accurate lactate threshold estimate. If the maximum heart rate setting is too high, the test will be too difficult to complete. If it is too low, the test will not record the lactate threshold. To accurately determine your maximum heart rate, make sure the Auto Detect feature is enabled on your device, or input your known maximum heart rate from a previous race or activity where you know that you hit your max. See "Detecting Performance Measurements Automatically" in your owner's manual for more information.

For best results, go for several runs after first using the watch in order for your watch to accurately learn your overall fitness level. Subsequent lactate threshold results will be more accurate once this is established.

The following are requirements specific to the different methods of detecting a lactate threshold.

Guided Test

NOTE: Newer devices do not have a guided test available. For more information see: Improved Lactate Threshold Measurement Feature.

Performing a guided test can help determine your lactate threshold estimate. The test must be completed while running outdoors with a GPS signal lock. Completing a warm-up jog prior to starting a guided lactate threshold test is recommended.

For instructions on performing a guided test, search "Performing a Guided Test to Determine Your Lactate Threshold" in your owner's manual.

Auto Detection

Auto detection is always on for a lactate threshold compatible device and will update when you achieve an activity that qualifies. Auto detection works best on runs that you spend some time in each zone as you increase the intensity of the activity. 

NOTE: Newer devices have the ability to turn off the auto detection feature. For more information see: Improved Lactate Threshold Measurement Feature.