What is Lactate? When glucose (will interchange with CHO) is broken down during exercise, the two by-products are energy (ATP) and pyruvate which is immediately converted to lactate. This process does not require oxygen, and is often called anaerobic or glycolytic. Lactate is a GOOD thing, because the aerobic system which breaks down FAT into energy also recycles lactate from the anaerobic system and converts it to energy/ATP.
Why do we test lactate? Like watts, lactate doesn’t lie! It allows athletes/coaches to asses performance over time, and set proper training zones. Testing lactate also provides insight to the strength of the aerobic and anaerobic system of an athlete, and provides several key physiological reference points (Aerobic Threshold, Lactate Threshold, etc) that can be used for structured training. A marathoner with great aerobic power should have a lactate curve that is more “flat” compared to a track athlete doing the 100m or 400m who should have a much steeper curve (more anaerobic power).
How do you set training zones based off lactate? A 3 zone (polarized) or 5 zone (Coggan) model are easily created based off the outstanding video lecture by Stephen Seiler, more references below. The reference points are LT1 and LT2, usually set at 2mmol and 4mmol respectively. See the links below for more information.
Does Lactate Cause Burning in the Muscles? No, the hydrogen ions that are released during anaerobic metabolism are probably what cause the fatigue felt when going “hard.” This occurs when exceeding the max lactate steady state or threshold, when the aerobic system is no longer able to clear the lactate and hydrogen ions being produced from the anaerobic system.
Testing, what is it like? This short 2 minute video gives a good overview. On a treadmill or bicycle with a smart trainer, speed / watts are increased every 3-4 minutes and a sample is taken. The testing can stop either after a reading higher than 4mmol is taken, or all the way to failure. The tiny prick does not hurt!
What about just doing a 20 min FTP test? CP20 testing “is not an accurate representation of the point at which an athlete’s body balances blood lactate accumulation and clearance.” Great read @ Fastcatcoaching on this. Easy to overshoot lactate threshold on a 20 minute test. A CP30 would be much more accurate, but that is a long time to endure pain! The lactate test is usually only really tough for the last two stages.
Example of results from a recreational runner getting back on a training program.
Another example (me) from the Spring of 2014 from a cycling lactate test. The VO2 value is measured from a metabolic cart, and not available via blood lactate testing. Major Universities or Olympic training centers will have metabolic carts (big $$).
Metabolic Cart Information: Contact Jeff Plasschaert at email@example.com for this type of testing at UF. GO GATORS!!or email
The red line shows the shift from FAT to CHO utilization, and approximates the 2mmol reference LT1 lactate value. What is notable is that thru base training, fasted training, and a higher fat diet, I was able to greatly shift from CHO to FAT utilization, especially at high intensity levels. Even during step 6 which would be the top of Z4/bottom of Z5 I was still using 33% FAT for fuel. Bonk proofing for endurance events!
The VO2 values are also important. Elite/Pro/World Class athletes can utilize up to 90% of their VO2 max at threshold. At the time of testing, I was using roughly 70% (~48/70ml/kg/mn) of my VO2 max at threshold. Still have a long way to go… : )
- Interpreting Lactate Curves for Ironman Athletes – EnduranceCorner blog
- Physiological markers for individualized training zones – Endurance Corner blog
- Polarized Training Published Article by Stephen Seiler and Espen Tønnessen – Journal Sports Science
- Lactate Testing for Triathlon – Lactate.com
- Dave Scott’s Lactate Testing Protocol for Swim, Bike, Run
I welcome any questions or comments on this topic! Thanks and message Jim @ http://www.protrifit.com to schedule any performance testing such as MAP (Max Aerobic Power) or Lactate Testing.