A threshold run is one of the most effective workouts for building speed and endurance. Done at 83-88% of your max heart rate, threshold running sits right at the edge of your comfort zone—just below the point where your body fatigues faster than it can recover.
Running at this “threshold” effort teaches your body to clear lactate more efficiently, allowing you to sustain harder efforts for longer periods. In simpler terms, it helps you hold a faster pace with less strain.
Whether you’re training for a 5K or a marathon, incorporating threshold runs regularly can dramatically improve your aerobic capacity, running economy, and mental toughness. They build the bridge between your easy miles and your top-end speedwork.
If you’re serious about becoming a stronger, more efficient runner, understanding and executing threshold training correctly is essential. In this guide, we’ll break down what threshold runs are, why they work, and how to incorporate them into your training plan safely and effectively.
The Honest Truth About Threshold Runs
Threshold running is one of the highest-yield training tools available to distance runners and one of the most commonly mis-prescribed. The popular framing of “threshold pace” collapses two distinct physiological landmarks (LT1 and LT2) into one number, and the right pace for a threshold run depends on which one you’re actually targeting. Knowing the difference between the two thresholds and what each session is meant to drive prevents the runner from training the wrong system at the wrong intensity.
LT1 vs LT2: two different thresholds, two different sessions
The lactate-threshold literature distinguishes between LT1 (the first lactate inflection, where blood lactate rises measurably above resting baseline, around 2 mmol/L for most amateurs) and LT2 (the maximal lactate steady state, where lactate clearance still keeps up with production, typically 3.5–4.5 mmol/L). Faude and colleagues’ comprehensive review documents that these two landmarks correspond to different paces and different physiological adaptations — they’re not interchangeable 1Faude O, Kindermann W, Meyer T. Lactate threshold concepts: how valid are they? Sports Med. 2009;39(6):469-90.. LT1 sits at roughly marathon pace for trained runners; LT2 sits at roughly the pace you could sustain for an hour all-out, which is closer to half-marathon pace. Most popular “tempo run” prescriptions implicitly target LT2 (the higher landmark), while many Norwegian-style polarized plans deliberately target LT1 (the lower landmark) for higher session volume and reduced fatigue cost.
What threshold sessions actually adapt
Sustained threshold work drives multiple physiological adaptations simultaneously: increased lactate clearance capacity (improving the pace at which lactate accumulation outpaces removal), improved running economy at race-relevant paces, and enhanced mitochondrial enzyme activity in slow-twitch fibres 2Holloszy JO, Coyle EF. Adaptations of skeletal muscle to endurance exercise and their metabolic consequences. J Appl Physiol. 1984;56(4):831-8.. The Seiler 80/20 polarised distribution — 80 percent easy aerobic, 20 percent at threshold or above — consistently outperforms threshold-only and pyramidal distributions in trained distance runners across multiple studies 3Seiler S. What is best practice for training intensity and duration distribution in endurance athletes? Int J Sports Physiol Perform. 2010;5(3):276-91.. Esteve-Lanao and colleagues showed that runners following polarised distributions improved 10K performance more than those following threshold-emphasis plans across the same training duration 4Esteve-Lanao J, Foster C, Seiler S, Lucia A. Impact of training intensity distribution on performance in endurance athletes. J Strength Cond Res. 2007;21(3):943-9.. The implication: threshold work is one component of a polarised plan, not the dominant one.
Calibrating threshold pace: what works and what doesn’t
Lab-based lactate testing is the gold standard for identifying LT1 and LT2 individually, but it’s expensive and impractical for most runners. The accessible alternatives have known accuracy limits. The “comfortably hard” or “could speak in short phrases” subjective marker corresponds reasonably well to LT2 for most runners. Heart-rate-based estimation places LT2 at approximately 88–92 percent of maximum heart rate for most amateurs, with LT1 at 78–82 percent 5Joyner MJ, Coyle EF. Endurance exercise performance: the physiology of champions. J Physiol. 2008;586(1):35-44.. The Daniels Running Formula approach uses race-time-based pace tables to back-calculate threshold pace as approximately 25–30 seconds per mile slower than 5K race pace for most amateur runners 6Daniels J. Daniels’ Running Formula. 4th ed. Human Kinetics; 2021.. The honest reading: any of these methods works adequately for training prescription; the runner who obsesses over precise pace calibration is solving for a level of accuracy that rarely matters in practice.
Session formats: tempo, cruise intervals, progression runs
Three session formats deliver threshold-zone work with slightly different cost-benefit profiles. Sustained tempo runs (20–30 minutes continuous at threshold pace) are the canonical session and produce the strongest LT2-specific adaptation when programmed once or twice weekly. Cruise intervals (4–6 minute reps at threshold with 1–2 minute easy jog recoveries) deliver comparable total time at threshold with reduced subjective fatigue cost — useful for runners with limited recovery margin 7Daniels J. Daniels’ Running Formula. 4th ed. Human Kinetics; 2021.. Progression runs that finish the last 4–6 km at threshold pace (after starting easy) layer threshold work onto long-run volume, which compounds aerobic-base development with threshold-specific adaptation. The Norwegian-singles training method extends this concept further with twice-daily sub-threshold (LT1) sessions accumulating high weekly volume at lower individual session intensity. The dose-response curve for threshold volume flattens past about 90–100 km/wk total training volume for most amateurs 8Tanda G. Prediction of marathon performance time on the basis of training indices. J Hum Sport Exerc. 2011;6(3):511-20..
Common threshold-run mistakes
Three patterns reliably make threshold sessions counterproductive. First, running threshold sessions too fast: most runners drift above LT2 into the “moderate-intensity grey zone” that produces fatigue without the threshold-specific adaptation, breaking the polarised distribution that drives endurance performance gains. Foster and colleagues documented that session-RPE drift past target intensity is one of the most common training-error patterns in distance runners 9Foster C, Florhaug JA, Franklin J, et al. A new approach to monitoring exercise training. J Strength Cond Res. 2001;15(1):109-15.. Second, running them too often: more than 2 threshold sessions per week with adequate recovery is rare in elite training and unsustainable for most amateurs — the Hulme review of running injury identifies sudden volume or intensity spikes as the dominant injury predictor 10Hulme A, Nielsen RO, Timpka T, et al. Risk and protective factors for symptoms and risk of injury among long-distance runners. Sports Med. 2017;47(5):869-86.. Third, running them on hilly terrain that breaks pace consistency: threshold work is intensity-controlled work, and hills convert it into VO2max-zone effort, which produces a different (and overlapping) adaptation but compromises the steady-pace stimulus that LT2 work specifically targets. The honest reading: threshold work is one of the highest-yield training tools when done at the right pace, the right frequency, and on the right terrain; it’s the most-mis-applied tool when those conditions aren’t met.
Understanding the Lactate Threshold: Where Your Body Reaches Its Breaking Point
We used to think that the lead-like, burning, heavy feeling in your legs during the last mile of a hard 5K or the last lap of an all-out mile resulted from “lactic acid” buildup.
When your effort level and running pace reach a certain point, you’ll notice you suddenly become much more breathless. This point, called the ventilatory threshold, is the point at which your body can no longer get enough oxygen with each breath, and it is closely tied to the lactate threshold.
The lactate threshold11Hoff, J., Støren, Ø., Finstad, A., Wang, E., & Helgerud, J. (2016). Increased Blood Lactate Level Deteriorates Running Economy in World Class Endurance Athletes. Journal of Strength and Conditioning Research, 30(5), 1373–1378. https://doi.org/10.1519/jsc.0000000000001349 is considered the tipping point at which your body must start producing energy anaerobically (without oxygen) via the metabolic pathway glycolysis rather than aerobic metabolism.
Glycolysis produces an end product called lactate, and while the lactate itself isn’t actually what causes the heavy, burning feeling, lactate production is associated with the production of hydrogen ions and other waste products that do cause discomfort and muscular fatigue.
At the lactate threshold, your body suddenly shifts from being able to clear lactate and other deleterious metabolic waste products at the same rate they are produced to becoming inundated with them due to the increased reliance on producing energy without sufficient oxygen (anaerobic threshold).
The lactate threshold in and of itself isn’t necessarily helpful, but knowing your running pace at your lactate threshold tells you how fast you can run before tipping the scales past “the point of no return.”
In other words, if you’re running a marathon or long-distance race and can keep your pace at or below your lactate threshold pace, you’ll be able to stave off crippling fatigue.
What is a Threshold Run?
In simple terms, a threshold run is when you run at or just below your lactate threshold pace, where your body can still clear lactate so you don’t reach complete exhaustion.
Threshold runs are also often called tempo runs, since threshold pace is sometimes referred to as tempo pace.
How Can I calculate My Threshold Pace?
There are several ways to find your threshold pace:
#1: Get A Lab Test
The most precise and accurate method to calculate your threshold pace is to get tested in an exercise physiology lab with blood lactate testing, but this is invasive and can be expensive.
If you’ve done a VO2 max test, your lactate threshold occurs around 83-88% of your VO2 max, so your threshold run pace would be the pace you are running at 83-88% of your VO2 max, according to your lab results.
#2: Calculate Your 60-Minute Max Effort Pace
Your threshold pace is roughly the pace you could hold at max effort for an hour of running.
In other words, if you were to enter a race measured in time instead of distance, and the goal was to run as far as you could in one hour, the pace you could hold for that one-hour race would be a good estimate of your threshold run pace.
#3: Use Recent Race Results
For most runners, threshold pace is somewhere between 10K and 15K race pace.
You can also take the results of these races or run a 3K or 5K time trial at a very hard effort, and then pop those race times into Jack Daniel’s VDOT running formula.
Here, you will calculate all of your current training paces, including interval training paces, half-marathon paces, marathon paces, threshold paces, etc.
#4: Use Your Heart Rate Training Threshold Zone
Threshold run pace can be determined by the pace you’re running when your heart rate is about 75-80% of your maximum heart rate.
#5: Use Rate of Perceived Exertion
A less precise estimate of your threshold training pace is to use the pace you’re running when your rate of perceived exertion (RPE) is about 6 out of 10, where 10 is an all-out sprint.
What Are The Benefits of Lactate Threshold Training?
Threshold runs can push the lactate threshold to faster paces, meaning that you can maintain a faster pace while still relying on aerobic metabolism without accumulating the byproducts of glycolysis. This means you can run faster and for a longer period of time without fatigue.
Additionally, threshold runs improve overall aerobic fitness and VO2 max. They train your body to be more metabolically efficient and can improve your ability to use fat for energy at faster paces.
Related: What’s a Good VO2 Max? Average VO2 Max By Age And Sex
How Do You Structure A Threshold Workout?
Threshold training12Burke, J., Thayer, R., & Belcamino, M. (1994). Comparison of effects of two interval-training programmes on lactate and ventilatory thresholds. British Journal of Sports Medicine, 28(1), 18–21. https://doi.org/10.1136/bjsm.28.1.18 involves any workout in which you maintain your threshold pace for a certain period of time. A threshold run may involve one continuous interval at the threshold training pace or several shorter intervals with slower recovery rest periods in between.
However, because the threshold pace isn’t an all-out effort, rest periods should be short. Here are some sample threshold workouts:
#1: Continuous Tempo Run
- 10–20 min warm-up
- 25–60 min at threshold effort (a sustainable hard pace you can sustain for about an hour)
- 5–10 min cool-down
#2: Broken Threshold Repeats
- 10–20 min warm-up
- 3–6 x 6–8 min at threshold pace with 1-3 min easy jog recovery between reps
- 5–10 min cool-down
#3: Long Threshold Intervals
- 10–20 min warm-up
- 3 x 10–15 min at threshold pace with 1-3 min easy jog between reps
- 5–10 min cool-down
#4: Extended Effort (10K Effort Focus)
- 10–20 min warm-up
- 2 x 20 min at 10K effort (slightly faster than threshold) with 90 sec easy jog between
- 5–10 min cool-down
#5: Long Run with Tempo Finish
- Run your regular long run
- Finish the final 20–40 min at threshold pace
How Do I Incorporate Threshold Runs Into My Training Plan?
Depending on your goals and current fitness levels, most coaches recommend doing one threshold workout per week.
More advanced runners may choose to have two threshold workouts per week: one dedicated tempo run at threshold pace and a second weekly workout with intervals at threshold pace, or incorporate threshold pace work into a longer-distance long run.
Even beginners can safely and effectively incorporate threshold runs into their workout program, as threshold pace is individualized.
Moreover, less aerobically fit runners will experience more significant improvements in lactate threshold through threshold training than more experienced distance runners.
As you become fitter, you’ll notice your threshold effort pace starts to feel easier. This is indicative of an increase in your lactate threshold, meaning your training is working. You will need to recalibrate your threshold run pace as you improve.
Threshold training improves your ability to produce energy without having lactate build-up in your muscles. In other words, threshold runs train your body to handle faster paces without producing the metabolic byproducts that make muscles feel like they’re on fire.
Calculate your threshold pace and add specific threshold training to your running program —you’ll see how quickly you reap the benefits!
To spice up your training plan with even more types of workouts, check out our interval training guide:
Hi. Merry Christmas! Thank you for an excellent post. I use Threshold training in my coaching, but i now have a far better understanding of the training tool. Thank you, Allen.