Lactate threshold is an important but often poorly understood concept for runners and endurance athletes. Most of us know that increasing our lactate threshold is a good thing but aren’t sure how to improve it from a practical perspective.
And I get it—terms like “lactate accumulation” and “anaerobic threshold” can start to sound pretty technical, pretty fast. But don’t worry, you don’t need a physiology degree to understand how it works—or to train in a way that boosts it.
As a coach, I break it down like this for my athletes: improving your lactate threshold simply means you can run faster, for longer, without feeling like you’re redlining. That’s a big win whether you’re training for a 10K PR or gearing up for your next marathon.
In this guide, I’ll walk you through the science of lactate threshold and share the two proven training methods I use with my runners to improve it.
What Is Lactate?
Before we discuss what the lactate threshold is, it’s helpful to understand what lactate is and why your lactate threshold matters.
Lactate is a molecule that is produced as a by-product of anaerobic energy metabolism.
Basically, when you run or perform exercise, your muscles need energy in order to contract and do work.
This energy comes in the form of a molecule called adenosine triphosphate (ATP), which can be produced through several different metabolic pathways depending on the oxygen availability, the intensity of your workout, the availability of fuel sources (carbohydrates, fats, etc.), and the type of muscle fiber (Type II “fast-twitch” fibers or Type I “slow-twitch” fibers).
During high-intensity exercise, such as when you are running at fast paces and feel fairly breathless, ATP must be made through anaerobic metabolism (without oxygen). This is primarily accomplished through a metabolic pathway known as anaerobic glycolysis.
In addition to not requiring oxygen, one of the benefits of anaerobic metabolism is that it is a very rapid way to generate energy, so if a lot of energy is needed quickly—such as when you’re running fast—it can be created through numerous fast cycles of anaerobic metabolism.
Glycolysis is a process that involves a set of chemical reactions that ultimately break down a glucose molecule (simple sugars from the foods we eat or stored in the body as glycogen) into cellular energy (the ATP we discussed), as well as lactate and a hydrogen ion.
The ATP is used to help the muscles contract and power your running stride, while the lactate can be shuttled to the liver, where it is further broken down to a molecule known as pyruvate, which can be used to produce more ATP (energy).
Lactate, or more accurately lactic acid, has been unfairly maligned for the burning feeling you experience in your legs when running at fast speeds or performing high-intensity exercise.
However, research suggests that lactate is actually beneficial to the body during and after exercise in numerous ways.1Todd, J., ‘Lactate: valuable for physical performance and maintenance of brain function during exercise’, Bioscience Horizons: The International Journal of Student Research, Volume 7, 2014, hzu001, https://doi.org/10.1093/biohorizons/hzu001 https://academic.oup.com/biohorizons/article/doi/10.1093/biohorizons/hzu001/242608
For example, the brain and heart can use lactate for energy, or it can be converted back into glucose in the liver or kidneys or reduced to pyruvate, which can then be used by nearly any cell in the body for energy.
Rather than lactate or lactic acid being to blame for the burning feeling and fatigue you experienced in your muscles at high intensities of exercise, the current consensus is that this sensation is due to the acidic environment, or drop in pH level, in the muscles as well as the phosphate that is left over after ATP has been broken down for use by your muscle fibers.
The drop in pH occurs due to the hydrogen ions that are also produced during anaerobic glycolysis.
Essentially, the hydrogen ions are the metabolic by-products your muscles produce at high intensities of exercise. These ions lower the pH in the muscles and blood, causing an acidic environment that results in a burning sensation and intense fatigue in your muscles.
What Is Your Lactate Threshold?
Lactate threshold (LT), which is also known as anaerobic threshold, is the point beyond which blood lactate levels rise dramatically with increased exercise intensity.
Essentially, at or below your lactate threshold, your body is able to clear or metabolize lactate, a byproduct of energy metabolism, at the same rate at which it is produced, so you don’t have any appreciable increase in your blood lactate levels.
At running speeds or exercise intensity levels above your LT, your muscles produce lactate at a rate that exceeds the liver’s ability to convert it into other molecules, causing a notable increase in your blood lactate concentration.
This is because the reliance on anaerobic glycolysis to produce energy is minimal at lower intensities of exercise, both because there’s enough oxygen for the muscles to generate energy through aerobic pathways and the rate that the muscles are consuming oxygen is slow enough that the muscles have time to meet that demand by generating oxygen via aerobic systems.
Even at lower intensities of exercise, glycolysis is still occurring to some degree, but the body is able to shuttle lactate out of the muscles as it is being produced, keeping the blood lactate levels relatively stable.
During lower intensities of exercise, blood lactate is typically 1-2 mmol/L.
However, once you start running faster than the pace that corresponds to your lactate threshold, your muscles need energy at a rate that is too fast for aerobic metabolism, and you also become unable to breathe steadily and comfortably.
Therefore, your muscles have to keep up with the need for energy, particularly in an oxygen-deprived environment, by ramping up glycolysis.
At this point, the blood lactate levels build up dramatically; in fact, the lactate levels rise over 20 mmol/L. This is your lactate threshold.
Running at a pace beyond your LT will cause the rapid fatigue and burning sensation in your legs every runner has experienced during a race or hard workout.
The confusing part is that if lactate production doesn’t actually cause the burning sensation, why is the lactate threshold associated with this discomfort?
The simple answer is that the hydrogen ions that do cause fatigue and discomfort are produced at the same rate as the lactate. Blood lactate levels are essentially a measurable biomarker of how much acid is accumulating in the muscles.
So, the lactate threshold can be used as an indication of the point at which the performance-inhibiting hydrogen ions are going to rapidly accumulate and cause a burning acidic feeling in your legs.
The pace that corresponds to your lactate threshold is the fastest you can run at a steady state without fatigue.
Why a Higher LT Means Better Race-Day Performance
The higher your lactate threshold, the faster you can run and the longer you can hold a higher-intensity pace before exhaustion, so LT corresponds with your potential running performance in any high-intensity distance race.2Deshayes, 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
According to research, typical lactate threshold values are as follows:
- Untrained or beginner runners: Corresponds to 60% of your VO2 max.
- Intermediate runners: Corresponds to 65% to 80% of VO2 max.
- Elite and highly competitive runners: 85% to 95% of VO2 max.
How to Determine Yours
Measuring your lactate threshold requires metabolic testing at an exercise physiology lab, but it’s also possible to estimate it with a field test. The test is fairly difficult and somewhat uncomfortable, so it is best for intermediate and advanced runners.
Lactate Threshold Field Test
You will need to wear a heart rate monitor.
- Warm up by running for 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 testing 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 LT.
How To Increase Lactate Threshold
Method #1 – Lactate Threshold Workouts
You can increase your lactate threshold through targeted interval workouts that focus on running at the pace or heart rate just below the point where fatigue and lactate buildup begin to spike.
This can involve performing shorter repeats, such as
- 5 x 4 minutes at LT pace (or 95-105% of your LT heart rate)
- 4 x 5 minutes at LT pace
- 2 x 10 minutes at LT pace
- 4-5 x 8 minutes at LT pace (for advanced runners)
Between these higher intensity intervals with increased power output, you should run at a low intensity for between 1 minute to 90 seconds to allow for lactate clearance
To progress these workouts, you can either increase the pace as your body’s ability to metabolise lactate increases, or increase the time length of each repeat.
Method #2 – Tempo Runs
Tempo runs are essentially lactate threshold intervals that involve running continuously for a minimum of 20 minutes.
For example, you might warm up with 10 minutes of easy running, then run at lactate threshold pace for 30 minutes, and then cool down with five minutes of easy running.
To progress tempo runs, you can increase the duration and or pace as your LT increases.
Incorporating one LT workout per week into your training plan is a great way to condition your body to get more comfortable and efficient at generating energy through aerobic metabolism at higher intensities.
These higher-intensity types of training sessions will increase lactate threshold and improve endurance performance.
FAQs
What Is The Difference Between Anaerobic Threshold And Lactate Threshold?
Anaerobic threshold and lactate threshold are often used interchangeably and occur at about the same level of intensity, and they both represent the maximum pace that you can sustain for an extended duration before significant fatigue sets in.
Consequently, both anaerobic threshold and lactate threshold require the same type of training to be improved.
The real difference between anaerobic threshold and lactate threshold mainly lies in the way that they are measured. Lactate threshold specifically looks at blood lactate concentration during graded exercise, whereas anaerobic threshold looks at changes in oxygen consumption and carbon dioxide exhalation.
What Is The Difference Between Lactate Threshold And VO2max?
VO2max (short for maximal oxygen uptake) refers to the maximum amount of oxygen your body can take in during exercise. It is measured in millilitres per kilogram per minute.
Lactate threshold is commonly expressed as a percentage of VO2max.
Blood lactate accumulation correlates with VO2max in the sense that the higher your intensity of exercise and the greater your level of anaerobic respiration, the closer your oxygen consumption is to your VO2max.
Looking for more information on what exactly is your Vo2 Max? Check out our guide for more information:
