Running has its own jargon, and it can be hard to find your way around it. That’s especially true of the threshold! Running at threshold is recommended by many runners and coaches. What is the anaerobic threshold? What is your threshold pace? Which workouts should you do, and for which goals? Let’s take a look.
The short answer
- The anaerobic threshold is the intensity above which lactate builds up in the blood and fatigue sets in much faster.
- You can generally hold it for 40 minutes to 1 hour: the pace lies between your 10K pace and your half marathon pace, or about 80 to 90% of your MAS.
- Typical workouts: 2 × 10′ to start with, up to 2 × 20′ or 30′ continuous with experience.
- One threshold session a week is generally enough; most of your training should remain easy running.
Contents
- Aerobic threshold, anaerobic threshold: what are we talking about?
- A story of lactate
- How do you determine your anaerobic threshold?
- What is your anaerobic threshold pace?
- Threshold and heart rate
- Running at the anaerobic threshold in training
- How many threshold sessions per week?
- What about the aerobic threshold?
- Frequently asked questions about the anaerobic threshold
- Sources
Aerobic threshold, anaerobic threshold: what are we talking about?
As exercise intensity increases, two turning points can be seen in the body’s response. They’re often called the first and second thresholds, or ventilatory thresholds 1 and 2 when they’re measured by analysing respiratory gases:
- The first threshold, or aerobic threshold: a moderate intensity, close to the top of your easy endurance pace. Below it, you can run for a long time while talking easily.
- The second threshold, or anaerobic threshold: a hard intensity, above which the effort quickly becomes difficult to sustain. This is the one people mean when they talk about “running at threshold”.
A story of lactate
Your body produces lactate all the time, even at rest, and reuses it as a source of energy, especially in the muscles and the heart (Brooks, 2018). Contrary to popular belief, lactate isn’t a waste product responsible for muscle soreness or fatigue: above all, it’s a good marker of exercise intensity.
The anaerobic lactate threshold (or simply anaerobic threshold) is the highest intensity at which lactate production and clearance remain balanced.
Above it, lactate builds up in the blood, which reflects disturbances in the muscle that make the effort much harder to sustain.
How do you determine your anaerobic threshold?
In practice, an effort at the anaerobic threshold can generally be held for between 40 minutes and 1 hour, depending on the runner. This usually corresponds to a speed between your 10K pace and your half marathon pace.
It’s hard to measure precisely in training. However, it can be estimated from race results, by estimating the speed you could hold in a one-hour race. That’s what we do in the RunMotion Coach app. You can also use our race time predictor to estimate your performances from your races.
To measure it more precisely, you need a laboratory test. Analysing exhaled gases (oxygen consumed and carbon dioxide released) makes it possible to identify the ventilatory thresholds. Fingertip blood samples track lactate concentration at each stage.
A value of 4 millimoles per litre is often quoted as a marker of the anaerobic threshold, but it’s only an average: depending on the runner, the threshold can be higher or lower, and the different methods used to determine it don’t always give the same result (Faude et al., 2009).
What is your anaerobic threshold pace?
The anaerobic threshold generally lies between 80 and 90% of a runner’s MAS (maximal aerobic speed). The higher this percentage, the more endurance the runner has. Here are the corresponding paces for a few MAS values:
| MAS | 80% of MAS | 90% of MAS |
|---|---|---|
| 12 km/h (7.5 mph) | 9.6 km/h: 6′15″/km or 10′04″/mile | 10.8 km/h: 5′33″/km or 8′56″/mile |
| 14 km/h (8.7 mph) | 11.2 km/h: 5′21″/km or 8′37″/mile | 12.6 km/h: 4′46″/km or 7′40″/mile |
| 15 km/h (9.3 mph) | 12 km/h: 5′00″/km or 8′03″/mile | 13.5 km/h: 4′27″/km or 7′09″/mile |
| 16 km/h (9.9 mph) | 12.8 km/h: 4′41″/km or 7′33″/mile | 14.4 km/h: 4′10″/km or 6′42″/mile |
| 18 km/h (11.2 mph) | 14.4 km/h: 4′10″/km or 6′42″/mile | 16.2 km/h: 3′42″/km or 5′58″/mile |
A beginner will be closer to the bottom of the range, a runner with a lot of endurance closer to the top. To fine-tune your paces to your profile, read our article on training paces.
Threshold and heart rate
Some GPS watch algorithms estimate your heart rate at the anaerobic threshold. Accuracy is generally fairly good with a chest strap, less so with a wrist optical sensor.
Heart rate at threshold varies a lot from one runner to another: rather than applying a standard percentage, use your own data or a test. You’ll find guidelines in our article on intensity zones and in our guide to using a heart rate monitor in training.
Running at the anaerobic threshold in training
English-speaking runners are big fans of threshold training: these are the famous tempo runs! These sessions teach you to hold a strong pace for a long time, which is invaluable for longer races.
Always start with a warm-up of at least 20 minutes and finish with 10 minutes of slow jogging. Here is a possible progression:
| Level | Threshold session | Recovery between blocks |
|---|---|---|
| To start with | 2 × 10′ | 4′ to 5′ jog |
| With a little experience | 2 × 15′ or 3 × 10′ | 4′ to 5′ jog |
| Experienced runner | 2 × 20′ or 1 × 30′ continuous (tempo run) | 4′ to 5′ jog |
The main aim of these sessions is to run economically and stay relaxed: you should finish the session feeling you could have done a little more.
They’re particularly useful for the marathon, but also for the 10K and half marathon, since this pace is close to 10K or half marathon race pace depending on your level. To see how threshold work fits with other sessions, read our article on the best workouts to improve over 10K and our guide to interval training.
How many threshold sessions per week?
One threshold session a week is generally enough, possibly alternating with a MAS session. Experienced runners preparing for a half marathon or marathon can sometimes do two.
Most of your training should remain at low intensity: among high-level endurance athletes, about 80% of sessions are done at low intensity (Seiler, 2010). If you’re training for a race, our plans put these sessions together for you: 10K plan, half marathon plan and marathon plan.
What about the aerobic threshold?
The aerobic threshold is the first threshold: the point where lactate starts to rise slightly above its resting value.
Its existence is well documented; what scientists debate is rather how to determine it, as the methods don’t all give the same result (Faude et al., 2009). It corresponds to a moderate intensity, close to the upper end of easy endurance running or slightly more active endurance.
Remember, easy endurance running is essential for progress and should make up the majority of your training.
Enjoy your tempo runs! And maybe one day you’ll become a true threshold runner!
Frequently asked questions about the anaerobic threshold
What’s the difference between the anaerobic threshold and MAS?
MAS is the speed at which you reach your maximal oxygen uptake: you can only hold it for about 6 minutes. The anaerobic threshold is slower, around 80 to 90% of your MAS, and can be held for 40 minutes to 1 hour. They’re trained with different sessions.
Are threshold pace and half marathon pace the same?
They’re close, but not identical. Depending on your level, threshold pace lies between your 10K pace and your half marathon pace. For a runner who finishes a half marathon in just over an hour, the two are almost the same; for a runner who takes 2 hours, half marathon pace is slower than threshold pace.
Can you train your threshold on trails?
Yes. On trails, it’s easier to go by feel or heart rate than by pace, which varies with elevation. Blocks of 10 to 20 minutes on a steady climb, at a hard but controlled effort, are a good way to work on your threshold.
How do I know if I’m running too fast at threshold?
At threshold, your breathing is fast and it’s hard to talk, but you stay in control. If you have to slow down in the last few minutes or you finish exhausted, you started too fast. It’s better to run slightly below your threshold pace than slightly above it.
Sources
- Faude O, Kindermann W, Meyer T. Lactate threshold concepts: how valid are they? Sports Med, 2009;39(6):469-490. DOI: 10.2165/00007256-200939060-00003
- Brooks GA. The science and translation of lactate shuttle theory. Cell Metab, 2018;27(4):757-785. DOI: 10.1016/j.cmet.2018.03.008
- Seiler S. What is best practice for training intensity and duration distribution in endurance athletes? Int J Sports Physiol Perform, 2010;5(3):276-291. DOI: 10.1123/ijspp.5.3.276
