5. VLAMAX IS -NOT- A RELIABLE MEASURE

Photo by Dan Cristian Pădureț on Unsplash

In the last years the software for tests analysis Inscyd has gained popularity and clients. The main ‘new’ concept/metric behind the software is VLamax.

What is VLamax?

VLamax is the maximum rate of blood lactate accumulation.

It is measured in mmol/L per second.

VLamax is ‘advertised’ as a metric representing the maximum anaerobic glycolysis rate. Inscyd suggests that measuring VLamax is critical to optimize training strategies based on the target competition. For example, an athlete with low VLamax which aim to win competitions decided by high intensity bursts should train to improve maximum anaerobic glycolysis rate (raise VLamax). On the other hand, an athlete with a high VLamax who wants to improve on long efforts should implement strategies to reduce VLamax. While this framework might sound attractive from a physiological point of view, a metric must be first reliable to be properly used. What does it mean?

A metric has a high reliability if it produces similar results under consistent conditions.

If a metric is not reliable, we are just losing our time because we can’t use it neither to compare different athletes nor to longitudinally monitor a given athlete’s progress.

Is VLamax a reliable metric?

In other words, if we measure Vlamax two times in the same standardized conditions, do we obtain similar results?

A study published by Harnish and Colleagues on Physiologia in 2023 (1) tried to answer this question.

---

WHAT DID THEY DO?

• Participants were 18 men and 12 women (30 total).

• Within a one week period, using standardized conditions (time of the day, nutrition and training before tests’ days) they performed two times the following VLamax test procedures on a Wahoo Kickr Cycle Ergometer:

  • 10 min self-chosen easy (Rating of Perceived Exertion, RPE, 3 on 10 points scale).

  • 1 min rest period during which a 3 μL blood lactate sample was taken.

  • 15s all-out sprint test

  • Sit in a chair resting passively while blood lactate samples were taken at 1 min, 3 min, 5 min, 7 min, and every 2 min afterwards until levels peaked and then dropped by at least 1 mM. In this way you make sure that true blood lactate peak is measured.

  

  The VLamax testing protocol used by Harnish et al. 2023. (1)

• VLamax was calculated using the peak and pre-sprint blood lactate samples, using the following calculation:

  

  VLamax calculation. From Harnish et al. 2023 (1)

---

WHAT DID THEY FOUND?

When comparing tests’ results obtained in the two different days:

• 15sec power output sprint was strongly reliable.

• However, VLamax was only moderately reliable.

Strongly and moderately are statistical terms used in scientific research. Let’s dig into numbers to understand what ‘moderately’ means for VLamax in a real world scenario.