What is lactate threshold?

Lactate threshold (LT) is the exercise intensity at which lactate starts to build up in the bloodstream faster than the body can remove it. This point is vital for endurance athletes because it indicates the shift from mostly aerobic (with oxygen) to anaerobic (without oxygen) metabolism.

Training at or around the lactate threshold improves the body’s ability to clear lactate. As a result, it enhances endurance and delays fatigue. This type of training can also promote better performance in long-distance running.

In this article, we will detail some major aspects of lactate threshold, including how you can measure and improve it.

How to measure your lactate threshold?

The calculation of your lactate threshold involves a test that gradually increases in intensity until you reach or approach exhaustion.

Here's a step-by-step guide on how this test is typically conducted:

Warm-up

Before the test, it is indispensable to warm up for about 10 to 15 minutes. This warm-up begins at a low intensity and gradually increases to a level similar to the starting point of the lactate threshold test.

The warm-up activates the oxidative energy pathways, which ensures that the body is ready for the subsequent exercise stages. It also helps reduce anxiety (something that can artificially elevate lactate levels).

Starting the test

The test begins at a relatively low work rate. This low intensity allows your blood lactate levels to remain close to resting levels at the beginning. The purpose is to establish a baseline for lactate production and clearance.

Gradual increase in intensity

The intensity of the exercise increases gradually. Typically, this involves stages of exercise where the work rate is progressively ramped up. Blood samples are taken at regular intervals during the test to measure lactate concentration.

Exercise mode

The mode of exercise can vary. Treadmill running and cycling ergometry are the most common methods. For endurance athletes, it is beneficial to use an exercise mode that closely resembles their competitive events to get the most relevant data (e.g., racing).

Blood samples

During the test, small blood samples are taken. These samples are analyzed for lactate concentration. The test continues until a point where there is a noticeable and sustained increase in blood lactate levels, which indicates the lactate threshold.

Lactate threshold

The goal is to identify the exercise intensity at which lactate begins to accumulate in the blood. This typically happens within 12 to 20 minutes of progressive exercise. If the test progresses too quickly or starts at too high of an intensity, it might not allow a proper baseline to be established.

Data analysis

After the test, the collected data is analyzed to pinpoint the lactate threshold. This involves plotting blood lactate concentrations against exercise intensity and the identification of the point where lactate levels show a marked increase.

How to train at your lactate threshold

Training at your lactate threshold revolves around exercising at or just above your lactate threshold heart rate. This type of training improves your endurance and performance through the optimization of your body’s ability to manage and use lactate.

Here’s how you can incorporate lactate threshold training into your workout routine:

Interval training

Interval training refers to the alternation between periods of high-intensity exercise with rest or low-intensity recovery periods. High-intensity interval training (HIIT) is the vigorous form of this type of exercise.

Do this twice a week and perform three to five 10-minute high-intensity intervals at 95% to 105% of your lactate threshold heart rate. There should be three minutes of rest between intervals.

This approach allows you to push your limits and provides recovery time to maintain high performance throughout the workout.

Continuous steady-state training

As the name suggests, continuous steady-state training focuses on keeping a steady and high-intensity effort for a prolonged period.

For ideal results, do this training twice a week and perform one 20- to 30-minute workout at high-intensity effort (95% to 105% of your lactate threshold heart rate).

Training volume and progression

Your initial training volume should match your current fitness level. Gradually increase the intensity and duration of your workouts.

Aim to increase your training volume by 10% to 20% each week. This gradual progression lowers the risk of overtraining and injury.

Monitor and adjust your training

Keep a detailed log of your workouts, including heart rate, duration, and perceived effort. This information is vital to monitor your progress and make adjustments.

Re-assess your lactate threshold every few months to ensure your training remains effective. If you notice a plateau or lack of progress, consider the adjustment of your training parameters (e.g., frequency, duration, intensity).

Tips for an effective lactate threshold training

Warm-up – Always start with a proper warm-up to prepare your body for the high-intensity effort and reduce the risk of injury.

Cool down – End each workout with a cool-down period to aid in your body’s recovery and remove any excess lactate from your muscles.

Nutrition and hydration – Proper nutrition and hydration are critical as well.

Zone 2 heart rate training and physical performance

Zone 2 heart rate training has gained popularity for its potential to enhance performance. This training zone is defined by moderate intensity and mainly uses Type I muscle fibers (known for their aerobic capacity and fat oxidation efficiency).

Zone 2 training balances fat and carbohydrate metabolism in an optimal fashion to maximize fat oxidation rates. This intensity is commonly termed 'FatMax' as it promotes mitochondrial function and enhances the body's ability to clear lactate. Lactate was traditionally viewed as a fatigue marker. However, it’s now recognized for its role as a quick energy source. Efficient lactate clearance reduces metabolic stress, which sustains performance.

The definition of Zone 2 involves the identification of the heart rate where lactate levels first rise significantly. This threshold (marked as 'LT1') signifies the upper end of Zone 2.

The key benefits of Zone 2 training include:

• Improved fat oxidation.
• Enhanced mitochondrial function.
• Better lactate transport between muscle fibers.

This training zone supports long-term endurance and recovery, which allows athletes to perform higher-intensity sessions effectively.