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Performance Testing, Part 4: Testing VLa max

Updated: Nov 28, 2022

VLa Max - The Tests

As we learned in the previous post, VLa max is the maximum rate of lactate production (max glycolytic rate). It is one of the athlete’s two “primary capacities”, the other being VO2 max. Functionally, the VLa max determines how much of the VO2 max can be “expressed” for the duration of an endurance race, acting like a gate keeper to the aerobic system. Practically, the VLa max gives critical insight into how the current fitness level is being achieved. Is the athlete an aerobic monster but metabolically inefficient? Or, is the athlete impressively fast considering their smaller aerobic engine. Having insight like this greatly impacts the training plan. This said, the coach and athlete should find a practical way to determine the VLa max. Just as I gave multiple protocols to determine or estimate VO2 max, I will give the same for VLa max. As with VO2 max, we will first look at a the gold standard test method and work our way to the less accurate yet still useful methods. For a refresher on the basics of VLa max, part 3 of this series titled “VLa max” is a good starting point.

Test 1: Lab Test

As with VO2 max (and most physiological metrics) going to a lab and properly using lab grade equipment will most likely give the most accurate results. There is no direct measure of VLa max because doing a real time muscle biopsy to measure the glycolytic rate inside the working muscle isn’t really an option. Also, because blood lactate concentration (BLC) is a function of both production and removal of lactate (not just production) BLC can not be used to determine only the production rate. However, there are two common lab protocols that can closely estimate it. One uses a 10-15 second maximum effort sprint. The other uses several sub-maximal efforts. Both protocols require blood lactate readings to be plugged into an algorithm. Unfortunately, if you live in the USA, there are very few (if any) labs that perform VLa max tests. However, some coaches will soon be providing in-person testing in the USA. If the lab test is not an option for you, there are other ways to estimate your maximal glycolytic rate.

Test 2: Field Test (with lactate)

A second and more feasible option to calculate your VLa max comes in the form of a field test with lactate. You can perform the lab VLa max tests in the field if you have a lactate meter and have access to the algorithm* that calculates the VLa max value. However, without access to this, you can’t actually calculate a true VLa max value. That said, you can still find your max BLC after a max effort. As stated before, the BLC is a function of both production and usage of lactate. The stronger the lactate removal system (aerobic system), the lower the BLC, assuming equal production. However, by doing a ~60 second maximum effort, you can fully activate the glycolytic system to produce lactate at the highest rate possible (function at VLa max). Because of the short duration and high intensity, even a strong aerobic system would not be able to clear such high volumes of lactate quickly enough so that BLC would remain low. So, what you would be left with after the effort is a max BLC. Using this value to compare to others’ max BLC is not particularly helpful in guiding your own training. However, comparing this value to your own results over time can give insight into the direction and magnitude of VLa max movement. Using this information, you can begin to determine the minimum effective does of certain types of training needed to reach your desired glycolytic rate.

Test 3: Field Test (without lactate)

If you don’t have access to a lactate meter (they are half the price of a power meter, so cost isn’t a huge barrier), then you can do a basic time trial in the field. Like the ~60 second time trial with lactate, you can do the same time trial without lactate. Such a time trial could be running a 400-600 on the track or swimming a 100 in the pool. Without lactate, you have limited insight into the metabolism besides knowing how fast you went and how it felt. If you see that your 400 or 100 time has gotten worse while your “tempo” or “threshold” workouts seem to be getting better, you can infer that the VLa max has been lowered. The opposite would be true if you improved your 400 or 100 time but your longer efforts were getting slower. The subjective feeling of the athlete during these tests is of equal importance. Could the athlete “empty” themselves during the short efforts or were they relatively fresh and recovered soon after? This feedback can give insight into the metabolism. All said, with the non-lactate field tests, it is probably best to do multiple lengths of time trials to create a more clear power/speed-duration curve. For more insight into how to make and use a power-duration curve, I would recommend Phil Skiba’s book, Scientific Training for Endurance Athletes.

Test 4: Athletic History and Perceived Feelings

Having access to a lab or lactate testing is great. The results are objective and the tests are repeatable. Field tests are helpful for the same reason. However, the coach can gain insight into the athlete’s predisposed physiology (and max glycolytic rate) by simply asking questions about the athlete’s past. Did the athlete do another sport before their current endurance sport? Was it a power/explosive sport? Does the athlete seems to excel when it comes to short races or workouts but lag in longer races, or perhaps the opposite? Does the athlete seem to respond well to a high volume of low intensity or a lower volume of high intensity? The answers to these questions can give the coach insight into the athlete’s physiology (fiber type distribution) and help guide the first training plan if no tests are available.


In the end, the purpose of any test is to gain useful insight into the athlete’s current physiological state that can be used to improve the training plan. VLa max testing is no different. Each time the coach tests the athlete, the change in VLa max should 1) tell the coach how the current fitness level is being achieved, 2) tell the coach how the athlete adapted to the past training block and 3) tell the coach how to prioritize the upcoming training to help the athlete reach their peak ability on race day. Knowing the VLa max is a great, if not necessary, tool to do this.

For more information on testing, coaching, or consulting, please feel free to email me at or message on Instagram (@robbie_deckard).

*The algorithm(s) used to determine VLa max are owned by some individuals and companies. One such person is a pioneer in the field of human metabolism, Jan Olbrecht. I believe Norwegian Olav Aleksander-Bu also has his own test. Companies such as INCSYD and Aero Tune also have their own.

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