Lactate Threshold Training for Athletes

Lactate threshold (LT), also known as anaerobic threshold, is the fastest a person can perform aerobic exercise in a steady state without fatiguing. Exercise performed above the LT causes blood lactate levels to rise suddenly. Lactate is a by-product of metabolism and exercise that the body is constantly producing.

Under normal conditions (rest and lower-intensity training), blood lactate is typically 1-2 mmol/L. During intense effort, it can rise over 20 mmol/L. Lactate levels are measured using blood draws at different stages of exertion.

Athletes often use their lactate threshold to determine how to train and what pace they can maintain during endurance sports. Because the lactate threshold can be increased greatly with training, many athletes and coaches devise training plans to increase this value.​

What Is Lactate Threshold?

During rest and steady-state exercise, the lactate levels in your blood are produced and removed in balance. The muscles, heart, and liver can use lactate as fuel during this time. During moderate exercise at a steady state, lactate can be absorbed quickly, but with high-intensity exercise, it is produced faster than the body can absorb it.

The lactate threshold is a point during exhaustive, all-out exercise at which lactate builds up in the bloodstream faster than the body can remove it. Anaerobic metabolism produces energy for short, high-intensity bursts of activity before the lactate build-up reaches a threshold where it can no longer be absorbed and, therefore, accumulates. This point is known as the lactate threshold.

This lactate threshold is marked by a slight drop in pH (from 7.4 to about 7.2). This drop is thought to cause fatigue and reduce the power of muscle contractions which can lead to a reduction in performance. The highest workload that can be maintained without lactate continuously accumulating over time is called maximal lactate steady state (MLSS).

Presumably, having a higher lactate threshold means an athlete can continue at a high-intensity effort with a longer time to exhaustion. Because of this, many consider LT a great way to predict athletic performance in high-intensity endurance sports.

Measuring Lactate Threshold

In the lab, lactate threshold tests are performed similarly to VO2 max testing, using either a treadmill or a stationary bike. The exercise intensity is increased in periods of about four to five minutes. Blood samples are taken with a finger stick at the end of each period. Heart rate, power output, and VO2 are often measured along with blood lactate concentration.

This process continues until the blood lactate concentration increases significantly. There tends to be a fairly obvious spike in the data. Because lactate threshold occurs sooner than VO2 max is reached, it is often measured as a percentage of VO2 max. Athletes and coaches measure the power output (usually in watts/kg) at the lactate threshold to design training programs.

Some research suggests that carbohydrate ingestion can influence lactate threshold. For example, one study found that a low-carbohydrate diet might shift the lactate threshold toward higher intensity workloads. Another review showed that consuming a low-carbohydrate, high-fat diet can increase lactate threshold in off-road cyclists. However, there is no evidence that this supports an increase in performance.

Estimating the Lactate Threshold

While not many people have access to a lab to measure their lactate threshold, a test can provide estimates. A simple method is a 30-minute time trial at a high, sustained pace. This test is suited to experienced athletes and should not be attempted by anyone who is not in top shape. The goal is to exercise at the highest effort you can sustain and monitor your heart rate throughout the test.

During this test, you can run, cycle, swim, or do another endurance sport that you can sustain for 30 minutes. You will need a heart rate monitor and a stopwatch or other method to time splits.

1. Warm up for 15 minutes.
2. Begin exercise and work up to your peak, sustained intensity within the first 10 minutes.
3. Record your heart rate each minute for the next 20 minutes.
4. Cool down.

Calculate your average heart rate over the 20-minute period. This figure is your estimated heart rate at your lactate threshold.

Other Measures of Exercise Intensity

Lactate threshold is not the only way to evaluate how hard you are pushing yourself during exercise. Athletes and trainers can use other methods to get an even more complete picture of performance. Some of these require lab testing, but others are easier to administer yourself.

VO2 Max

Another way to measure maximum effort is VO2 max. VO2 max is the maximum consumption of oxygen that your body can take in and use while exercising. That ability to take in and use oxygen is an indicator of your cardiorespiratory fitness level.

VO2 max is measured in a lab using equipment that tracks the amount of oxygen you inhale versus the amount of carbon dioxide you exhale. During this test, you will be pushed to maximum intensity. Your maximum heart rate may also be recorded during this test.

Having a higher VO2 max means that you have superior cardiovascular ability than someone with a lower VO2 max. You can increase your VO2 max by becoming more conditioned through training.

Heart Rate

Your maximum heart rate is the fastest rate your heart beats in one minute. Unlike VO2 max, a higher maximum heart rate doesn't mean that you are in better cardiovascular condition.

However, being aware of your maximum heart rate helps you track your progress and determine what heart rate target you should aim for. Using your maximum heart rate is more complicated (ideally, you need a chest-strap heart-rate monitor, and you must take readings very frequently) yet more accurate than using the rate of perceived exertion scale.

Rate of Perceived Exertion

Your rate of perceived exertion is another way of testing how hard you are working. Perceived exertion measures how you feel your body is working by tapping into physical sensations you experience during exercise, such as your heart beating more rapidly, your breath becoming faster, increased sweating, and muscle fatigue. The Rate of Perceived Exertion Scale (RPE) runs from 6 at the lowest amount of effort to 20 and the maximum level of exertion.

You determine how hard you are working and tie that perceived effort to a number between 6 and 20 based on the sensations you experience during exercise. While 6 is no exertion, such as being at rest, 9 is walking at an easy pace, and 12 to 14 is moderate intensity. Levels 15 and above are heavy exertion and considered a vigorous intensity, such as running.

Increasing the Lactate Threshold

With training, athletes can tolerate higher intensity exercise for longer periods of time. Endurance athletes, including those who participate in mini or full triathlons and duathlons and/or half and full marathons, may wish to increase their lactate threshold through training, recovery, and nutrition.

Assessing and tracking your lactate threshold using testing can help you determine if your efforts are paying off. Knowing your baseline and then having a plan to progress with your training allows you to keep adapting and improving.

Training

Lactate threshold training means increasing exercise intensity so you train at or just above your LT heart rate. This training can be interval training or steady-state training. A combination of interval, high-intensity training, and continuous steady-state training may work best. The duration of your exercise should be based on your current fitness level and goals. For example:

• Interval LT training sample plan: Twice a week, perform three to five 10-minute high-effort intervals at 95% to 105% of your LT heart rate, with three minutes of rest between intervals.
• Continuous LT training sample plan: Twice a week, perform one 20- to 30-minute workout at high-intensity effort (95% to 105% of your LT heart rate).

Increase your training volume by 10% to 20% each week to progress. Remember to track your progress and re-test every few months to see if your training efforts are working. If not, you might need to adjust by adding frequency, time, or intensity.

Recovery

Recovery is vital for optimal performance without overtraining. Rest days or days of light work should be interspersed between your active training days. Recovery work such as mobility, stretching, foam rolling, massage or other methods might boost recovery as well. Remember to get enough sleep each night, as that will play a critical role in your performance and recovery.

Nutrition

Nutrition is also a big part of recovery and performance. To boost your LT during training and racing, you need to make sure you can exercise at a high intensity without running out of glycogen stores. This requires careful nutritional planning in both the pre-exercise meal and post-exercise meals.