Lactate Threshold

Lactate threshold is the exercise intensity at which lactate (lactic acid) starts to accumulate in the bloodstream. In running, this intensity level is estimated in terms of pace, heart rate, or power. When a runner exceeds the threshold, fatigue starts to increase at an accelerating rate. For experienced runners, the threshold occurs at approximately 90% of their maximum heart rate and between 10 km and half-marathon race pace. For average runners, the lactate threshold often occurs well below 90% of maximum heart rate. Knowing your lactate threshold can help you determine how hard to train or when to push yourself during a race.

If you already know your lactate threshold heart rate value, you can enter it in your user profile settings (Setting Your Heart Rate Zones). You can turn on the Auto Detection feature to automatically record your lactate threshold during an activity.

Performing a Guided Test to Determine Your Lactate Threshold

This feature requires a Garmin® chest heart rate monitor. Before you can perform the guided test, you must put on a heart rate monitor and pair it with your device (Pairing Your Wireless Sensors).

The device uses your user profile information from the initial setup and your VO2 max. estimate to estimate your lactate threshold. The device will automatically detect your lactate threshold during runs at a steady, high intensity with heart rate.

TIP: The device requires a few runs with a chest heart rate monitor to get an accurate maximum heart rate value and VO2 max. estimate. If you are having trouble getting a lactate threshold estimate, try manually lowering your maximum heart rate value.
  1. From the watch face, select START.
  2. Select an outdoor running activity.

    GPS is required to complete the test.

  3. Hold Menu symbol.
  4. Select Training > Lactate Threshold Guided Test.
  5. Start the timer, and follow the on-screen instructions.

    After you begin your run, the device displays each step duration, the target, and current heart rate data. A message appears when the test is complete.

  6. After you complete the guided test, stop the timer and save the activity.

    If this is your first lactate threshold estimate, the device prompts you to update your heart rate zones based on your lactate threshold heart rate. For each additional lactate threshold estimate, the device prompts you to accept or decline the estimate.

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March 2024