How can I determine my Lactate Threshold Heart Rate?

The simplest way to determine your heart rate threshold is to back into them through pace. First, follow the guidelines under the Pacing Testing section of this article to establish your Threshold Pace (TP).

The next step is to determine your Lactate Threshold Heart Rate (LTHR) from your TP. To do this, warm up with 10 minutes of easy jogging and then accelerate to your TP on a smooth, flat path or road. Wait for your heart rate to stop increasing and plateau. The number you see after it levels off is your LTHR. Now go to the Run and Cycling Heart Rate section of the 80/20 Zone Calculator and enter your lactate Threshold Heart Rate. Your seven heart rate training zones will be calculated automatically.

If you have not yet established your TP, you can find your LTHR independently through a time trial. Begin with a warm-up that consists of 15 minutes of easy jogging with a few 15-second surges at the pace you intend to run for the time trial. Next, increase your effort to the highest level you feel you can sustain for 20 minutes and hit the lap button on your heart rate monitor watch. Five minutes into the test, hit your lap button again. Fifteen minutes later, at the end of the 20-minute time-trial, hit the lap button again or end the time trial. Your LTHR is your peak 15-minute average within that 20-minutes test (the average heart rate in beats per minute (BPM) of the final 15 minutes of the 20-minute test).

Note that Lactate Threshold Heart Rate is slightly different in running than it is in other aerobic activities, so if you choose to cross-train, you’ll need to do separate tests in each activity.

Also note that heart rate is significantly influenced by factors such as temperature, humidity, sleep, stress, time of day, and even when you last ate. Therefore, your Lactate Threshold Heart Rate test result is specific to the environment and conditions in which you test. For example, an LTHR test indoors in February in the morning will not be the same as an LTHR test in July outdoors in the afternoon. Perform your LTHR in the environment that most accurately represents where you will do the bulk of your training.

For various reasons, most athletes find that their threshold is 5-10 bpm lower indoors than outdoors. For this reason, it may be practical to maintain separate indoor and outdoor HR zones. Or simply adjust your zones appropriately when moving between outdoor and indoor environments.