Introduction to VLamax

29 May 2020

This post is a static version of an interactive playground that is available here.

VLamax is defined as the maximum rate of lactate production that one can achieve. The unit of VLamax is mmol/L/min or mmol/L/s.

VLamax can be determined by doing e.g. a 20 second sprint (usually seated to mimic muscle recrution at lower intensities) an recording the lactate concentration pre and post (maximum) test and using the formula:

$\dot{V}La_{max} = \frac{La_{maxPost} - La_{maxPre}}{t_{test} - t_{alac}}$

$t_{alac}$ is the duration of the test for which the glycolytic system is not yet active and is usally defined as the time untill power declines below 3.5% of peak power (citation needed).

But, there's a catch: Usually, when people talk about VLamax they are not talking about the actual maximum value but the shape of the curve that describes the relation between intensity (e.g. power) and lactate production:

lactate production vs lactate combustion plot

Since lactate combustion is linked to pyruvate availability, the area between the production and combustion curve below anaerobic threshold denote the pyruvate availability:

pyruvate availability area plot

You can also plot this directly (green for pyruvate excess, red for deficit):

pyruvate availability plot

Since fatty acid metabolism also relies on/is limited by pyruvate availability and since the lactate shuttle takes precedence in using pyruvate, one could state that pyruvate excess is a measure of fatty acid metabolism. Following this reasoning, maximum fat metabolism occurs at maximum pyruvate availability.

In the chart below the dotted line denotes the intensity at which maximum fatty acid metabolism occurs. The FatMax zone is positioned around this intensity.

fatmax plot

In a similar train of thought as with FatMax, one could state that the intensity at which the most pyruvate is available, the lactate shuttle process is also most active (remember that lactate shuttle takes precedence over fatty acid metabolism).

Ergo: The optimal intensity for recovery during intense workout bouts is identical to your FatMax zone:

vlamax optimal intensity plot

W'balance vs lactate balance

The VLamax has some parallels to the critical power concept (or power duration modelling in general).

This is very experimental, but I thought it would be interesting to see how a concept like W'balance would look like in the "VLamax" world. Let's call it "lactate balance".

sample workout

w prime balance

lactate balance