Blood lactate threshold (LAC) testing has been practiced and studied by exercise physiologists for over 100 years. A LAC test is a simple and effective way to provide an athlete with a variety of valuable information. This test can:

• Determine your training intensity zones
• Gauge changes in fitness
• Determine race day pacing strategies

This short guide will explain the basics of LAC testing and why you, as an endurance athlete, may consider having our team conduct a test with you.

WHAT IS BLOOD LACTATE?

In short, lactate is the byproduct of your muscle cells' use of glucose. Your body recruits muscle cells to do work (speed/pace/power). At a relatively low intensity, your Type 1 (slow twitch) muscle fibers do most of the work using relatively low amounts of glucose and the lactate produced is readily recycled by those same cells for energy. As the intensity increases, Type 2 (fast twitch) muscle fiber cells are recruited in greater numbers. These fibers use a lot of glucose and thus produce a lot of lactate, much of which drifts into the bloodstream. This increase in lactate that is found in the bloodstream is what we’re measuring when we conduct a blood lactate threshold test.

LACTATE THRESHOLD

Lactate Threshold is a term used to describe the highest effort that can be sustained for an extended period of time (approximately 20 minutes to 1 hour) without having to slow down. As long as you maintain this effort, your lactate levels remain elevated above your baseline, but constant. Increase the intensity, even a little, and lactate levels will continue to rise until you’re forced to slow down.

In the most simple terms, athletes with lower threshold values have higher glycogen utilization levels and higher lactate production. These athletes will typically perform worse compared to athletes with higher threshold values.

THE TEST

When conducting a LAC test, we are actually looking for more than just an athlete’s lactate threshold. We are interested in their baseline lactate values, the point where their lactate begins to increase for the first time from the baseline and the lactate threshold itself. All of this information tells us something about the athlete.

We typically test an athlete following a progressive ‘ramp’ protocol. In this type of test the intensity progresses every 4 to 5 minutes, building from very easy to as hard as the athlete can go. A small sample of blood is taken from the ear or finger every step of the test while measuring heart rate, pace, power (if on the bike), and perceived exertion. The length of the test depends upon the athlete’s ability, but the typical length is between 30 minutes and one hour.

Once the athlete has finished the test and cooled down, we graph out the results (see Image 1), looking for the changes in blood lactate accumulation. We compare the blood lactate levels to their corresponding heart rates and can begin to determine appropriate training zones.

Some athletes choose to have multiple LAC tests done throughout the season. A single test is insightful but multiple tests help to determine if an athlete’s training is having the desired effect. In some cases, an athlete will even take ‘spot’ lactate samples during an actual workout to confirm their blood lactate levels are where they want them to be.

Image 1: Lactate threshold test results. Lower line is blood lactate values. Upper line is heart rate. 

PRACTICAL APPLICATION OF LAC TESTING

TRAINING ZONES

The primary goal of a LAC test is to approximate an athlete’s training zones. Training zones are used to clarify the general objective and desired intensity of a workout. Classically, an athlete has to guess what pace, power or heart rate to use in these zones. LAC testing provides a deeper level of clarity.

Zone 1: A conversational effort used for warming up, down, or very long aerobic efforts of 8+ hours. Lactate levels stay at baseline and/or below 1.5 mmol.

Zone 2: The classic ‘base building’ intensity but also race pace for many events around 8 hours in duration. Lactate levels between 1.5 - 2.4 mmol.

Zone 3: “Easy-Fast” pace and race pace for events between 1 - 3 hours. Lactate levels between 2.5 - 4 mmol.

Zone 4: A “threshold” effort sustainable for 20-60 minutes. Lactate levels between 4 - 6 mmol.

Zone 5: A very hard effort used for interval training or events <20 minutes. Lactate levels are over 6 mmol.

After a LAC test, an athlete should go out and confirm the Zones “feel right.” Science, technology, and knowledge are great but as athletes we should never forget to utilize and develop our natural sense of feel.

RACE PACING

The nerves, excitement and adrenaline inherent to racing often results in an athlete starting their event way too slow or too fast. By using a slightly modified test protocol and testing at their goal race pace, we can determine if an athlete’s goal pace is within reach.

QUESTIONS & ANSWERS

Q | How much does a LAC test cost?

A LAC test cost $125 plus the cost of each blood lactate stick ($3.50)  used during the test. A typical athlete will use 5 - 8 blood lactate sticks.

Q | How long does the test take?

Typically 30 - 45 minutes are needed for testing, and another 30 - 45 minutes to review and discuss the results.

Q | How is a LAC test different from an FTP test?

Cyclists commonly use a 20 min FTP test to estimate their one hour ‘lactate threshold’ power. Unfortunately, research shows little correlation between this 20 minute test and an individual’s actual one hour threshold power. Additionally, for athletes racing events much longer than one hour, a 20 minute test is much higher than actual race intensity. A LAC test can more accurately estimate an athlete’s Zones 1 through 3, which is actual race intensity for events lasting over two hours.  

Q | Do I need to taper before a test?

We recommend training easy the day before a LAC test. Testing during an athlete’s recovery week is a typical practice as the athlete will not have to modify their training for the test itself.

RESOURCES

1. Dr. Iñigo San Millán, ‘What is Lactate and Lactate Threshold Testing?’, Training Peaks, accessed January 2023 from www.trainingpeaks.com
2. Inglis, et al. (2019) Maximal Lactate Steady State Versus the 20-Minute Functional Threshold Power Test in Well-Trained Individuals: “Watts” the Big Deal? International Journal of Sports Physiology and Performance.  https://DOI:10.1123/ijspp.2019-0214
3. Lactate Threshold Discussion- Part 1, Lactate.com, assessed January 2023 from www.lactate.com

CONTACT INFORMATION

Tri Town Bicycles

1510 N 13th St.

Boise, ID 83702

208-297-7943

www.tritownboise.com