Lactate threshold is an important but often poorly understood concept for runners and endurance athletes.
Many runners know that increasing their lactate threshold is a good thing but aren’t sure how to improve lactate threshold from a practical perspective.
In this article, we will discuss how to increase lactate threshold, why lactate threshold training is important, and how to do lactate threshold workouts.
We will cover:
- What Is Lactate?
- What Is Lactate Threshold?
- Why Is It Good to Increase Lactate Threshold?
- How to Determine Your Lactate Threshold
- How To Increase Lactate Threshold: 2 Training Methods
Let’s dive in!
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 byproduct 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) 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.
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 byproducts 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 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 lactate threshold, 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 increase dramatically; in fact, the lactate levels can rise over 20 mmol/L. This is your lactate threshold.
Running at a pace beyond your lactate threshold 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 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 Is It Good to Increase Lactate Threshold?
The higher your lactate threshold, the faster you can run and the longer you can hold a higher-intensity pace before exhaustion, so lactate threshold corresponds with your potential running performance in any high-intensity distance race.
Doing lactate threshold workouts is how to improve lactate threshold over time.
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 Your Lactate Threshold
Measuring your lactate threshold requires metabolic testing at an exercise physiology lab, but it’s also possible to estimate your lactate threshold with a field test.
Estimating your lactate threshold requires a fairly difficult and somewhat uncomfortable test, so it is best for intermediate and advanced runners.
You will need to wear a heart rate monitor.
Here is how to estimate your lactate threshold while running:
- 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 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.
How To Increase Lactate Threshold: 2 Training Methods
You can increase lactate threshold with lactate threshold workouts. Lactate threshold workouts involve running at your lactate threshold pace or exercising at a heart rate that corresponds to your lactate threshold.
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)
Tempo runs are also lactate threshold workouts. 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.
Incorporating one lactate threshold 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. This will increase lactate threshold.
Looking for more information on what exactly is your Vo2 Max? Check out our guide for more information!
