What heart rate is sub-threshold?
Just under your own threshold heart rate. In Norwegian singles practice, your reps sit from roughly 90% of it up to just under it. Early reps finish 10 to 15 beats below it, and later reps finish nearer to it. On a watch that's Zone 4, 80 to 90% on either method. The cue that matters is crossing into Zone 5.
Don't be thrown when percentages of max disagree, Bakken's 80 to 87% against 85 to 90% on coaching and calculator sites. They scatter because the threshold itself varies: 90.6 ± 2.5% of max in recreational runners.
With Intervals + HR Zones on, RunBeat calls each rep and tells you your zone inside it, so when you hear Zone 5, ease off:
Distance Intervals in RunBeat
RunBeat calls the start and end of every rep, measured by GPS.
What heart rate should a tempo run be?
Daniels puts a tempo run at 88 to 92% of maximum heart rate. Pfitzinger puts it at 82 to 90% of max heart rate, or 76 to 87% of heart rate reserve. On percent of max, Pfitzinger's band sits inside Zone 4 and Daniels' runs from the top of Zone 4 into Zone 5.
A tempo run is the coaching name for a continuous run at threshold. Both coaches anchor the number to a race effort you could hold for 50 to 60 minutes (Daniels) or 45 to 60 (Pfitzinger).
Where does Zone 2 end and the first lactate threshold begin?
Zone 2 ends at 70% on either method, and the first lactate threshold sits above it: 80.7 ± 4.9% of maximum heart rate, or 73.3% of heart rate reserve, in recreational runners. On a watch, that's the Zone 3/4 line under percent of max and inside Zone 3 under heart rate reserve. Either way, the average runner's Zone 2 ends before the first threshold.
A 2025 expert panel, mostly from cycling, expected zone 2 just below the first threshold at roughly 70 to 80% of max. Without a lab, some coaches use the decoupling test to estimate where your own first threshold sits.
How do you find your lactate threshold heart rate?
Run 30 minutes alone at race effort, press lap at 10 minutes, and take your average heart rate over the last 20. That average approximates your threshold heart rate, in Friel's test. If you run it with others or in a race, make it 60 minutes.
In competitive runners and triathletes, a 30-minute trial's heart rate landed within about 8 beats of a threshold measured directly at 4.0 mmol/L of blood lactate. Wear a chest strap, so wrist-sensor error isn't part of the result. In Norwegian singles practice, 98% of the result is taken as the threshold heart rate.
What do Garmin and Apple Watch do with a lactate threshold heart rate?
Garmin takes the number and Apple Watch doesn't. Enter it in your Garmin's user profile, or let Auto Detection, on by default, estimate it during an activity. You can base your zones on it, with the threshold as "the boundary between zone 4 and zone 5" in Garmin's words. Some models still document a guided test, which needs a Garmin chest strap, a VO₂ max estimate, and GPS.
Apple Watch sets your zones as a percentage of maximum heart rate from your health data, and lets you edit zones 2 to 4 by hand. No lactate threshold appears in the watchOS 27 guide or the Ultra 3 pages as of October 9, 2026.
How long should a threshold run be?
20 to 60 minutes continuous in Daniels' coaching, 20 to 40 in Pfitzinger's. Daniels' ideal tempo run is a steady 20 minutes. He caps a week's threshold work at the lesser of 10% of mileage and 15 miles (24 km).
Norwegian singles counts work time instead: 20 to 25% of your weekly running time, maybe 30%. At seven hours a week, that's 28 to 35 minutes of work in each of three sessions.
How often should you do threshold runs?
Two to three sub-threshold sessions a week in Norwegian singles, plus a long run, with the rest easy. Pfitzinger's published schedules carry one lactate threshold day a week.
The method's week is three quality sessions, three easy runs, and a longer easy run. Start with two quality sessions if structured intensity is new to you. The method's own reasoning for the higher count is that its reps stay under the threshold rather than at it.
Sources
- Nuuttila O-P, Kaikkonen P, Sievänen H, Vasankari T, Kyröläinen H. The accuracy of fixed intensity anchors to estimate lactate thresholds in recreational runners. European Journal of Applied Physiology. 2025;125(8):2161-2171. doi:10.1007/s00421-025-05748-8. Full text read. 165 recreational runners (64 women, 101 men, 36 ± 6 years), maximal incremental treadmill test with measured maximum heart rate. Source for the first lactate threshold at 80.7 ± 4.9% of maximum heart rate (women 83.6 ± 4.2, men 78.9 ± 4.4) and 73.3 ± 6.5% of heart rate reserve (women 76.5 ± 6.1, men 71.3 ± 6.0), blood lactate 1.7 ± 0.5 mmol/L; and for the second threshold at 90.6 ± 2.5% of maximum heart rate (women 91.7 ± 2.2, men 89.9 ± 2.4) and 87.0 ± 3.4% of heart rate reserve. The two methods describe the same runners; neither is ranked by these figures.
- Hafen PS, Vehrs PR. Sex-Related Differences in the Maximal Lactate Steady State. Sports. 2018;6(4):154. doi:10.3390/sports6040154. Full text read. 22 well-trained distance runners (12 women, 10 men). Corroboration for the spread of the second threshold: maximal lactate steady state at 89.5 ± 8.8% (men) and 88.6 ± 6.8% (women) of maximum heart rate.
- Sitko S, et al. What Is "Zone 2 Training"?: Experts' Viewpoint on Definition, Training Methods, and Expected Adaptations. International Journal of Sports Physiology and Performance. 2025;20(11):1614. doi:10.1123/ijspp.2024-0303. An invited commentary from a 14-expert panel working mainly in cycling, not a study. Source for the panel's placement of zone 2 just below LT1 or VT1 and its expected heart rate there, roughly 70 to 80% of maximum or 80 to 90% of the heart rate at LT1, stated as an expectation and never as a cutoff.
- Daniels J. What You Need to Know About Threshold Training. Runner's World, December 1, 2005, updated December 31, 2022, adapted from Daniels' Running Formula by permission of Human Kinetics. The author's own text, read at the Internet Archive's August 27, 2026 capture; the live page blocks automated reading. Source for T-pace at 83 to 88% of VO₂ max or 88 to 92% of maximum heart rate, the 50-to-60-minute race-effort anchor, the steady 20-minute tempo run, and tempo runs of 20 to 60 minutes.
- Daniels J. Daniels' Running Formula, 3rd ed. Human Kinetics, 2014, p. 243, publisher-authorized preview. Source for the cap on threshold work: no more than the lesser of 10 percent of weekly mileage and 15 miles (24 km) at T pace.
- Pfitzinger P. About the plans; Training pace table. pfitzingercoaching.com, read October 9, 2026. The author's own site. Source for LT pace at about 82 to 90 percent of maximal heart rate, 76 to 87 percent of heart rate reserve, for experienced runners, and the 45-to-60-minute race-effort anchor. His books give slightly different bands by edition; those are not stated above.
- Pfitzinger P, Latter P. Faster Road Racing. Human Kinetics, 2014, p. 15, publisher-authorized preview. Source for the tempo run as a continuous run of 20 to 40 minutes at LT pace. Pfitzinger P, Douglas S. Advanced Marathoning, 3rd ed. Human Kinetics, 2020, p. 193, publisher-authorized preview. Source for the one lactate threshold session a week in his schedules.
- Friel J. Joe Friel's Quick Guide to Setting Training Zones. TrainingPeaks, May 4, 2012, updated July 18, 2026; and Determining your LTHR, joefrieltraining.com, April 28, 2011. The author's own text at his publisher and his own site. Source for the 30-minute solo time trial, the lap at 10 minutes, the last-20-minute average as the approximation of lactate threshold heart rate, and the 60-minute version with others or in a race.
- McGehee JC, Tanner CJ, Houmard JA. A comparison of methods for estimating the lactate threshold. Journal of Strength and Conditioning Research. 2005;19(3):553-558. doi:10.1519/15444.1. PMID 16095403. Abstract read; the full text is paywalled with no open-access deposit. 27 competitive distance runners and triathletes; the criterion a directly measured blood lactate of 4.0 mmol/L, one threshold convention among several. Source for the time-trial heart rate not differing significantly from the criterion, SEE 8.0 beats per minute. The abstract does not state whether the heart rate was the last-20-minute or the whole-trial average, so nothing above says the paper tested Friel's averaging.
- Vobejda C, Fromme K, Samson W, Zimmermann E. Maximal constant heart rate: a heart rate based method to estimate maximal lactate steady state in running. International Journal of Sports Medicine. 2006;27(5):368-372. PMID 16729378. Abstract read. 31 subjects. Corroboration only: a 30-minute maximal-constant-heart-rate method against the heart rate at maximal lactate steady state, r = 0.820, SEE 6.73 beats per minute.
- Sartor F, et al. Wrist-worn optical and chest strap heart rate comparison in a heterogeneous sample of healthy individuals and in coronary artery disease patients. BMC Sports Science, Medicine and Rehabilitation. 2018;10:10. doi:10.1186/s13102-018-0098-0. 199 volunteers, a 2018 prototype wrist sensor. Source for the chest-strap sentence only, as a pattern: the spread against a strap was widest where the sensor moves, with mean error under 3 BPM. No figure from it attaches to any named product.
- The sub-threshold archive, sites.google.com/view/sub-threshold (home page and the sirpoc84 posts page, read October 9, 2026), and the Norwegian singles community guide, norwegiansingles.run (updated September 30, 2026, §1.2 and §2). The method's own documents, in the community register. Source for Copeland's practice: threshold heart rate taken as 98% of the 30-minute test's number, reps "even up to 90% under" it, early reps finishing about 10 to 15 beats below it and later reps approaching it from below; the share of weekly running time at 20 to 25% (maybe 30%), 28 to 35 minutes of work per session at seven hours a week, and three sessions of 24 minutes of work; two to three sub-threshold sessions a week plus a long run, three quality sessions with two to begin; and "a chest strap helps avoid measurement errors."
- Runner's World, April 23, 2026 (Marius Bakken, quoted). Source for sub-threshold at "80 to 87 percent of max heart rate", Bakken's figure. The page blocks automated reading; the quote was read from a search-index extract of it, which is the floor for this entry.
- trainingzones.io (April 2, 2026), sweetspot.run, and runlovers.it (February 9, 2026), read October 9, 2026. Source for the 85 to 88% and 85 to 90% of maximum heart rate renderings of sub-threshold work, stated as what each site gives; none cites a measurement.
- Garmin Forerunner 970 Owner's Manual, v6, September 2026 (www8.garmin.com). Source for manual entry of a lactate threshold heart rate in the user profile, Auto Detection on by default for maximum heart rate and lactate threshold, and zones based on BPM, %Max. HR, %HRR, or %LTHR. The manual prints no %LTHR bands and carries no guided-test topic. Garmin fēnix E Owner's Manual (EN-SG). Source for the guided test's requirements: a Garmin chest heart rate monitor, the VO₂ max estimate, and GPS. Garmin blog, May 2, 2025, "Your lactate threshold then becomes the boundary between zone 4 and zone 5", quoted. Whether manual entry changes auto-detection is not stated above; Garmin's support page on it blocks automated reading.
- Apple Watch User Guide, View Heart Rate Zones (watchOS 27); the watchOS 26 and 27 release notes; the Apple Watch Ultra 3 newsroom post and tech specs. All read October 9, 2026. Source for zones as a percentage of maximum heart rate calculated from health data and for manual editing of zones 2, 3, and 4. The words "lactate" and "threshold" appear on none of them; the absence is stated as of that date.