Lactate testing, by definition, is the measurement of lactate levels in the blood. It is performed through blood sampling (pricking) across a step-wise test of increasing intensity. It is very similar to blood glucose testing but with an athletic performance component.
One of the goals of the test is to pinpoint one's lactate threshold. Physiologically speaking, this is where our anaerobic system, dominates our aerobic system. From a biochemical sense, it is where excess muscular acidity builds up and is signified by a sudden rise in lactate levels. In terms of athletic performance, it is the maximum intensity we can sustain. This means it's the point of diminishing returns with regard to effort vs. volume.
Looking at it in terms of cause and effect, metabolic processes (namely anaerobic respiration) result in the build up of hydrogen ions. These ions inhibit muscular contraction and result in the onset of fatigue. Lactate production/synthesis is a marker for our body's attempt to buffer (reduce) muscular acidity. Hence, elevated lactate levels is a biological marker for excess acidity which results in the onset of fatigue.
Some people mistakenly interchange lactate testing with lactate threshold testing. As mentioned earlier, the former is a protocol that measures actual lactate levels while the latter determines the point where lactate levels rise suddenly. In short, lactate threshold testing is a subcomponent of lactate testing; thus, lactate threshold testing cannot be used to refer to actual lactate testing. This is because there is no way to measure lactate levels without actual blood sampling.
The confusion arises because there are means to estimate one's lactate threshold through non-invasive means. 20min time trials (to measure maximum sustainable effort), heart rate formulas (to estimate Lactate Threshold HR or LTHR, near infrared spectrometry (pulse oximetry via LEDs) are a few examples. These methods, since they do not actually measure lactate levels, are at best, an estimate of one's threshold. They can never predict actual lactate levels. There is a reason why hospitals and clinics prefer blood tests over symptomatic observation and analysis. In terms of accuracy, nothing beats an objective and absolute guide. Measuring blood lactate means observing the cause of the phenomenon while most non-invasive tests merely measure the effects.
Apart from knowing your threshold, blood lactate testing allows you to take a peek into the state of one's aerobic and anaerobic systems. This allows us to determine what kinds of workouts are most beneficial to each athlete. In line with this, blood lactate testing also allows us to pinpoint one's training zones by analyzing the lactate curve (the plot of how lactate increases relative to intensity). Each training zone has a particular purpose such as building one's aerobic endurance, lactate tolerance etc. These zones serve as a guide in how to go about each training session. They also help us avoid blowing up during raceday by letting us manage our efforts intelligently.
In closing, blood lactate testing is an extremely accurate way of pinpointing one's threshold/redline. However, it has added benefits that no other single test can yield. Unlike non-invasive methods, blood lactate testing also gives you the data needed to manage training sessions, develop weaknesses, and execute a "plan of attack." In reference to UFC Champion Connor McGregor's famous quote: "Timing beats speed, precision beats power" I say "Accuracy and precision beat resolution, and understanding the cause beats observing the effects." #KnowTheDifference #KnowYourNumbers #LactateTesting #FlyingDonVCoaching