How to test your LTHR
- Warm up for 10–15 minutes with a few strides.
- Run 30 minutes alone at the best effort you can sustain — as if it were a race. Avoid a group or race setting, which pushes heart rate higher.
- Press lap at 10 minutes. Your average heart rate for the final 20 minutes is your estimated LTHR.
- Note the pace for the whole 30 minutes too — it is close to your threshold pace.
This is Joe Friel’s field test as described in his guide to setting zones. Retest every 6–8 weeks or after a clear change in fitness.
Joe Friel running zones
| Zone | Name | HR, % of LTHR | Pace, % of threshold pace |
|---|---|---|---|
| 1 | Recovery | < 85 % | slower than 129 % |
| 2 | Aerobic | 85–89 % | 114–129 % |
| 3 | Tempo | 90–94 % | 106–113 % |
| 4 | Sub-threshold | 95–99 % | 99–105 % |
| 5a | Super-threshold | 100–102 % | 97–100 % |
| 5b | Aerobic capacity | 103–106 % | 90–96 % |
| 5c | Anaerobic capacity | > 106 % | faster than 90 % |
Pace percentages apply to pace (time per km), so 114 % of a 5:00/km threshold pace is 5:42/km. Source: Joe Friel’s quick guide to setting zones (TrainingPeaks).
Threshold pace from a race
Threshold pace is roughly what you could race for an hour. This calculator estimates it from your race using the Daniels & Gilbert VDOT equations — the 60-minute race pace your result implies. For fast runners that is close to half-marathon pace; for runners whose 10K takes about an hour it is close to 10K pace.
| 10K time | Threshold pace /km | /mile |
|---|---|---|
| 35:00 | 3:36 | 5:48 |
| 40:00 | 4:06 | 6:35 |
| 45:00 | 4:35 | 7:22 |
| 50:00 | 5:03 | 8:08 |
| 55:00 | 5:32 | 8:54 |
| 1:00:00 | 6:00 | 9:39 |
Can’t do a time trial? LTHR is often around 85–90 % of maximum heart rate, but individual variation is large. Use that only as a starting point.
Use your LTHR in the 80/20 zones calculator or set sub-threshold reps with Norwegian singles.
Last reviewed: September 2026 · Health disclaimer