What is Lactate Threshold?
The human body primarily favors the use of oxygen as its main fuel source. However, as exercise intensity increases, the body is unable to uptake (utilize) enough oxygen to keep up with the demands of working muscles. In this circumstance, the body turns to glucose as its energy source through a process called glycolysis, in which glucose is broken down into a substance called pyruvate.
As the body continues to demand fuel, two options can occur:
- If enough oxygen is present, pyruvate is recycled and used by the body as an energy source
- If oxygen is limited however, pyruvate is further broken down into lactate, which allows the body to breakdown even more glucose. This causes muscle acidity which is a defense mechanism to prevent damage from excessive exertion.
There is a common misconception that lactate threshold is simply the production of lactate. However, lactate threshold is the workload at which the body is producing lactate faster than it can get rid of it; i.e: it is when muscle activity will start to be inhibited to prevent damage. The repercussions of this are felt as pain/ reduced power output/ fatigue by the athlete.
As middle distance and endurance athletes, lactate threshold is an important value which assists athletes in determining:
- Race pace intensities in aerobic competition events
- What intensity is required to elicit an improvement in the lactate threshold curve (how to increase workload without accumulating as much blood lactate)
- The amount of rest needed between exercise bouts to bring blood lactate below threshold
- Accurate aerobic training zones
Lactate Threshold Test vs VO2 Testing
The purpose of a Lactate Threshold Test is to determine the maximal lactate steady state which is defined as the highest blood lactate concentration and workload that can be maintained over time without a continual blood lactate accumulation.
A long accepted gold standard measurement of aerobic fitness has been VO2 max, which assesses the athlete’s ability to consume oxygen during exercise. However, in recent years there has been evidence to suggest that lactate threshold testing is a greater indicator of aerobic performance and more sensitive to training adaptations.
As coaches, VO2 max values may be a good representation of where an athlete stands in comparison to other athletes during the season. Yet, it serves almost no value in the day to day planning and prescription of exercise programs. Lactate threshold profiling on the other hand, allows coaches to prescribe training intensities more accurately and is much easier to re-assess on a routine basis.
Lactate Threshold Testing vs Functional Threshold Power Test
The functional threshold power (FTP) represents the maximum power an athlete can sustain for one hour. In today’s high performance industry, FTP is commonly utilized by coaches to estimate training zones and serves as a great tool for coaches who do not have access to lab testing. However, there are 3 main issues with estimation:
- Accuracy of heart rate zones – Heart rate is not a percentage of anything and therefore, cannot be identified without taking blood measurements
- Equal banding of training zones – depending on what type of aerobic training the athlete performs the most, one training zone may be bigger than another. This needs to be identified
- Once FTP is identified, what type of training needs to be prescribed to improve aerobic fitness? (volume or interval) – If training zones are banded equally, coaches cannot determine which training zone needs the most attention
Therefore, an FTP assessment cannot accurately detail an athlete’s aerobic profile.
Lactate profiling addresses all three issues. By taking blood lactate samples in conjunction with heart rate and workload, coaches may determine when different training zones begin and correspond these values to what heart rate and workload was recorded during the test.
These values may significantly improve the way coaches plan, prescribe and most importantly, individualize training programs to get the most out of their athletes.
What a Lactate Threshold Test involves:
Athletes are set up with their bike on the Wahoo Kickr (11 speed; 11-28 cassette), and a heart rate monitor chest strap which will be monitored throughout the test.
Resting blood lactate concentration and heart rate will be taken prior to the test. Blood lactate will be measured by pricking the finger and transferring a small drop of blood to the portable lactate analyzer.
The intensity of the test begins relatively easy and gradually increases with each 3 minutes stage. At the end of each stage heart rate, blood lactate concentration and rate of perceived exertion is measured.
Stages continue until 2 stages after lactate threshold is achieved or when athletes are no longer able to maintain the workload.
What to bring to the test?
- Heart rate monitor (optional)
Lactate Profiling at Precision Athletica in Sydney
Our facility has certified Exercises Physiologists who aim to provide coaches and athletes with baseline and recurring testing, and recommendations to individualize aerobic training programs.
For more information about lactate profiling, or to book a Lactate Threshold Test, please email our Exercise Physiologist Justin Trang – [email protected]