LTHR Heart Rate Zone Calculator
Calculate your personalized training zones based on your Lactate Threshold Heart Rate (LTHR) using the Joe Friel model.
Your Training Zones
| Zone | Description | Heart Rate Range |
|---|
Understanding Lactate Threshold Heart Rate (LTHR)
Lactate Threshold Heart Rate (LTHR) is arguably the most important metric for endurance athletes like runners and cyclists. Unlike Maximum Heart Rate (Max HR), which is often estimated using inaccurate formulas like "220 minus age," LTHR is a functional marker that represents the intensity you can maintain for approximately one hour.
Why Use LTHR Instead of Max HR?
Maximum Heart Rate is largely determined by genetics and age, but it doesn't tell you much about your actual fitness level. LTHR, however, reflects your metabolic fitness. As you get fitter, you can sustain a higher percentage of your Max HR at your threshold, making LTHR-based zones much more accurate for daily training prescriptions.
How to Find Your LTHR
The gold standard for determining LTHR without a lab test is the Joe Friel 30-minute time trial:
- Perform a thorough warm-up.
- Start a 30-minute "all-out" time trial (run or cycle) alone.
- 10 minutes into the test, hit the "Lap" button on your heart rate monitor.
- Your average heart rate for the final 20 minutes of the test is your estimated LTHR.
The 7 Training Zones Explained
- Zone 1 (Recovery): Very light intensity used for active recovery days.
- Zone 2 (Aerobic/Base): The "bread and butter" of endurance training. Build aerobic capacity and fat metabolism.
- Zone 3 (Tempo): Moderate intensity that requires focus. Improves glycogen storage.
- Zone 4 (Sub-Threshold): Just below your threshold. Crucial for increasing your LTHR.
- Zone 5a (Super-Threshold): Just above threshold. Used for shorter intervals.
- Zone 5b (Aerobic Capacity/VO2 Max): High intensity for building top-end engine power.
- Zone 5c (Anaerobic Capacity): Explosive, short bursts of maximum effort.
Example Calculation
If an athlete performs a time trial and finds their average heart rate for the final 20 minutes is 170 BPM, their zones would be calculated as follows:
- Zone 2 (85-89%): 145 to 151 BPM.
- Zone 4 (95-99%): 162 to 168 BPM.
- Zone 5a (100-102%): 170 to 173 BPM.