Distance runners can incorporate countless types of running workouts into their training plans to improve key performance metrics like top speed, running economy, and biomechanics. These workouts target various physiological systems, helping athletes push their limits and achieve their goals.
As a running coach, lactate threshold training is one of my favorite and most effective methods for improving endurance performance. I include threshold workouts in all of my runners’ cycles at one point or another, depending on their experience and running goals.
The lactate threshold is the point at which lactate—a byproduct of carbohydrate metabolism—accumulates in the blood faster than the body can clear it. This occurs during sustained, high-intensity exercise, signaling a shift from aerobic to anaerobic.
Training at or near your lactate threshold improves your body’s ability to tolerate and clear lactate, enabling you to maintain faster paces for longer durations.
In this training guide, we will explore precisely what lactate threshold training is, its benefits, and how to measure yours so you can start reaping the benefits of threshold workouts.
What Is Lactate Threshold Training?
Lactate threshold training helps improve your lactate threshold, one of the key physiological markers of endurance performance.
But what is occurring physiologically at the lactate threshold?
Below the lactate threshold or anaerobic threshold, the ATP that is being produced by the muscle cells to fuel physical activity is primarily generated through aerobic metabolic pathways.1Ghosh, A. K. (2004). Anaerobic threshold: its concept and role in endurance sport. The Malaysian Journal of Medical Sciences : MJMS, 11(1), 24–36. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3438148/
Aerobic metabolism, also known as aerobic respiration, includes the Krebs cycle, which is also known as the citric acid cycle, and the electron transport chain.
While some amount of anaerobic glycolysis also occurs to produce ATP during lower-intensity exercise efforts, aerobic metabolism provides almost all the energy for the cells.
This means that whatever small amount of lactate byproduct that is being produced can be shuttled to the liver and converted into pyruvate.
The pyruvate molecule can then be shuttled back to muscle cells and fed into aerobic metabolic pathways to produce more energy.
Therefore, the production of lactic acid or lactate is at or below the rate at which the body can clear the lactate from circulation so there is no appreciable increase in blood lactate levels.
However, once the runner is working at a high-intensity level for his or her fitness level, ATP cannot be produced fast enough through aerobic metabolism to supply all of the energy that the muscle cells need.
Additionally, as you run faster, you are often unable to breathe deeply and quickly enough to inhale enough oxygen for aerobic metabolism.
Remember, the term aerobic means “with oxygen,“ so if your muscle cells are starved of adequate oxygen, anaerobic metabolism (“without oxygen”) glycolysis is the only option for producing ATP.
Finally, another major shift during high-intensity exercise is greater recruitment of fast-twitch muscle fibers to help power the faster running speed than there is during low-intensity exercise, during which slow-twitch muscle fibers are generally sufficient.
Fast-twitch muscle fibers are capable of much higher power output and stronger contractions for faster running speeds, such as 400m race pace efforts, compared with slow-twitch muscle fibers.
However, the fast-twitch muscle fibers lack sufficient mitochondria and enzymes for aerobic metabolism.
Mitochondria are the organelles (small, specialized components in cells such as muscle fibers) that can produce ATP through aerobic metabolism. Instead, fast-twitch muscle fibers have enzymes for glycolysis in the cytosol (fluid portion) of the cells.
As you approach your maximum heart rate during higher-intensity exercise, these fast-twitch muscle fibers are recruited to help meet the higher power output required by the faster running speed.
Because there are insufficient mitochondria, the glycogen being fed into the muscle cells has to be broken down for energy production via anaerobic glycolysis.
Together, these changes during vigorous exercise are the reason that the body has to shift from aerobic respiration to glycolysis or at least a greater reliance on anaerobic energy production.
Thus, the anaerobic threshold is the point at which this metabolic change occurs from aerobic to anaerobic metabolism.
When glycolysis occurs in anaerobic conditions, a major byproduct is lactic acid.
The lactic acid molecules quickly dissociate into lactate and hydrogen ions (each lactic acid molecule produced dissociates into a lactate molecule and a hydrogen ion, which is an acid).
The reason that the anaerobic threshold and lactate threshold are strongly correlated or can essentially occur at the same point in terms of the running speed or power output is that once you are relying heavily on anaerobic glycolytic energy production, there is an accumulation of lactate molecules.2Poole, D. C., Rossiter, H. B., Brooks, G. A., & Gladden, L. B. (2020). The anaerobic threshold: 50+ years of controversy. The Journal of Physiology, 599(3). https://doi.org/10.1113/jp279963
This is because lactate molecules are being produced much faster than the liver can convert them into pyruvate.
As a result, there is a significant build-up in blood lactate, evidenced by increased blood lactate levels.
Typically, the lactate threshold is considered to be the point at which blood lactate concentration exceeds four mmol/L.
How Do You Determine Your Lactate Threshold?
There are so many biometrics and functional parameters we can measure regarding physical performance for endurance sports or high-intensity athletic performance.
For example, your one-repetition maximum (1RM) for an exercise is the maximum amount of weight you can lift with proper form, making the 1RM a great indicator of absolute strength for a given movement.
Aerobic capacity can be measured with a VO2 max test, and the vertical jump test is a great assessment of lower-body power and strength.
Unfortunately, there isn’t a simple lactate threshold test that you can conduct in the field, meaning outside of an exercise physiology lab or sports medicine center, that will be as accurate as actually measuring blood lactate levels.
After all, your true lactate threshold is a physiological marker that refers to your blood lactate concentration.
Therefore, the only real way to measure lactate threshold is to conduct a lactate threshold test in a lab while a technician is measuring changes in your blood lactate concentration.
A lactate threshold test involves graded exercise, such as running on a treadmill, while monitoring heart rate and measuring blood lactate accumulation.
Before well-trained runners or elite athletes who train for endurance sports hit their lactate threshold, changes in blood lactate levels should be relatively insignificant, even as running speed or intensity increases.
This is because there is not a significant amount of lactic acid, which dissociates into lactate and hydrogen ions, being produced.
Therefore, the lactate threshold test takes periodic blood draws to measure the mmol of lactate in your blood samples.
Once the blood lactate measurement is at least 4 mmol/L of blood, the lactate threshold test can essentially stop.
The running speed or power output for cyclists at which the lactate levels in the blood reach the blood lactate threshold cutoff can then be used in training as the running pace for tempo runs and lactate threshold workouts.
Endurance cyclists can use the power output from a lactate threshold measurement test to set power training zones.
Runners and endurance athletes can also use their lactate threshold heart rate from a lactate threshold testing procedure to help set up heart rate training zones.
The lactate threshold heart rate is the heart rate that correlates to your lactate threshold.
You can also use your lactate threshold heart rate for heart rate training when you are doing tempo runs or other maximal lactate steady-state workouts.
Essentially, the lactate threshold heart rate is a tangible biomarker that can be used in endurance training to guide lactate threshold workouts.
Unfortunately, measuring lactate threshold or anaerobic threshold outside of an exercise physiology lab where you are getting blood draws will simply be an estimation of your lactate threshold running speed or cycling power output.
You can do field tests to help estimate your lactate threshold, but again these do not truly measure lactate threshold.
Here is a lactate threshold running test that can help you estimate your lactate threshold heart rate and running speed. You will need a heart rate monitor.
Lactate Threshold Field Test
- Warm up by running 10-15 minutes at an easy pace.
- Begin working up to a pace that feels like the maximum steady state pace you can run before crossing that threshold into exhausting efforts.
- After 10 minutes, begin a timer for another 20 minutes at this pace (30 minutes total), recording your heart rate during this 20-minute piece.
- Cool down with 5-10 minutes of easy jogging.
The average pace that you were able to maintain during the final 20 minutes of the threshold effort is the pace that corresponds with your lactate threshold, and the average heart rate during this time should be used as you are estimated heart rate at your lactate threshold.
What Is a Good Lactate Threshold for Runners?
Because endurance training can improve your lactate threshold, elite athletes and those who have been following the best training plans will have a higher lactate threshold than beginners or those with a poor fitness level.
A good lactate threshold occurs at a higher relative percentage of your VO2 max or higher relative percentage of your maximum heart rate, while a low lactate threshold will be reached at a lower relative percentage of VO2 max and maximum heart rate.
According to FirstBeat Analytics, the lactate threshold of well-trained runners and endurance athletes typically is around 90% of their maximum heart rate.3Firstbeat Analytics. (n.d.). Www.firstbeatanalytics.com. https://www.firstbeatanalytics.com/en/features/lactate-threshold/#:~:text=Well%2Dtrained%20runners%20typically%20find
For elite runners, this typically correlates to 10K race pace, and for advanced runners, the lactate threshold running pace is somewhere between 10K and a half marathon race pace.
For less experienced runners, the lactate threshold typically is reached somewhere below 90% of max heart rate and sometimes as low as about 50% of VO2 max and 55% of maximum heart rate.
According to exercise physiology research, average lactate threshold values by training level are as follows:
- Untrained, or beginner runners: Corresponds to 50-60% of your VO2 max, which is around 55-65% of your maximum heart rate.
- Intermediate runners: Corresponds to 75-85% of your VO2 max, which is around 80-90% of your maximum heart rate.
- Elite and highly competitive runners: 85% to 95% of VO2 max or 90-95% of maximum heart rate.
Practically applying these lactate threshold levels to endurance training programs and race pace performance basically results in the need for beginners to run at a slower pace or low-intensity exercise relative to elite athletes.4Deshayes, T. A., Jeker, D., & Goulet, E. D. B. (2019). Impact of Pre-exercise Hypohydration on Aerobic Exercise Performance, Peak Oxygen Consumption and Oxygen Consumption at Lactate Threshold: A Systematic Review with Meta-analysis. Sports Medicine, 50(3), 581–596. https://doi.org/10.1007/s40279-019-01223-5
This is so that they don’t start relying heavily on anaerobic glycolysis to provide energy for their workout.
Thus, ultimately, for distance runners and endurance athletes, your race pace for running distance events or power output for cycling is limited by your lactate threshold.
What Are the Benefits of Lactate Threshold Training For Endurance Athletes?
Lactate threshold training is a very important component of a training program for endurance athletes, such as runners training for a half marathon or a marathon, cyclists, triathletes, and individuals training for other endurance sports.
This is because the higher your lactate threshold, the faster you can run or the greater the intensity you can sustain before fatiguing.
This is because elite athletes and well-trained endurance athletes with a good lactate threshold can run at a faster race pace or power output and at a higher percentage of their maximum heart rate and VO2 max, while relying on aerobic metabolism before crossing over to having to rely too much on anaerobic systems.
Again, only when anaerobic metabolism and fast-twitch muscles are being recruited there is the accumulation or build-up of the fatiguing byproducts associated with your lactate threshold.
Therefore, the higher your lactate threshold, the faster you can run, and the longer you can perform higher-intensity exercise before exhaustion.
Ultimately, lactate threshold correlates to your potential running performance in any high-intensity distance race such as a 10K, half marathon, marathon, triathlon, etc.5Deshayes, T. A., Jeker, D., & Goulet, E. D. B. (2019). Impact of Pre-exercise Hypohydration on Aerobic Exercise Performance, Peak Oxygen Consumption and Oxygen Consumption at Lactate Threshold: A Systematic Review with Meta-analysis. Sports Medicine, 50(3), 581–596. https://doi.org/10.1007/s40279-019-01223-5
Lactate threshold workouts can improve your lactate threshold over time.
How Can I Improve My LT Pace?
Lactate threshold workouts are specifically designed to improve your lactate threshold by training within a specific effort range.
By training at your lactate threshold heart rate or pace, you could improve the efficiency of your metabolic systems so that you aren’t creating the lactic acid byproducts of anaerobic glycolysis and recruiting fast-twitch muscles at a lower intensity.
The goal of lactate threshold workouts is to get more comfortable training at lactate threshold intensity and gradually stimulate physiological adaptations so you become more efficient at clearing lactate and hydrogen ions.
This will allow you to run faster or push your body at a higher intensity before crossing the anaerobic threshold.6Ghosh, A. K. (2004). Anaerobic threshold: its concept and role in endurance sport. The Malaysian Journal of Medical Sciences : MJMS, 11(1), 24–36. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3438148/
Running coaches and exercise physiologists use different structures for lactate threshold training workouts, including the following:
- Maximal lactate threshold steady-state workouts: One continuous workout at your lactate threshold training pace. This would include things like a 20 to 30-minute tempo run.
- Longer threshold intervals, such as 2-3 x 10 minutes at lactate threshold pace or power, for running and cycling, respectively, with 90 seconds of rest between each lactate threshold interval.
- Numerous shorter intervals at lactate threshold pace or lactate threshold heart rate, such as 4 to 6×5 minutes 4 6×1200 m with 60 to 90 seconds of rest between each threshold training interval.
Endurance athletes doing triathlon training can use lactate threshold power output on the bike to set the training zones for these lactate threshold workouts.
Thoroughly warm up and cool down before your lactate threshold training sessions.
It is also important not to increase your training volume with lactate threshold interval training quickly; take time over your training program to increase the volume in terms of the number of reps for threshold interval training workouts or the length of tempo runs.
Doing too much too soon can lead to overtraining and may cause more fatigue than positive physiological adaptations.
Working with a running coach or following a training plan is a smart approach to guiding your workouts and helping you reach your running goals.
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I’m training using a modified version of the Norwegian Method, but using a Schwinn Airdyne and a Precor Stepper.
I’m 70, trying to drop some weight and get into shape following a double hernia surgery, and before a right knee total replacement.
Your article was very helpful, informative, and technical, but not obtuse.
After both knees are done, I’m looking forward to running again, after a 25 year hiatus due to knee pain. Thanks for your help, Sarah.