The Drive with Peter Attia Q&A: You Asked, VO2 Master Answered

Episode #294 of The Drive with Peter Attia features coach Olav Aleksander Bu. During their conversation, they discuss how to measure and train for peak athletic performance, as well as the role of VO2 Master in helping triathletes achieve their full potential. 

In this article, we answer 10 frequently asked questions we received from our audience since the podcast was released. 

Q: Do you have any reference materials about using the VO2 Master analyzer in non-traditional testing? 

A: The VO2 Master blog provides numerous examples of the VO2 Master analyzer being used in various environments, including the University of Hawaii’s preliminary research for outrigger canoe paddling. Competitive and recreational paddlers with and without spinal cord injury were part of the pilot study. Another example of precedent-setting research is Trek Bikes’ work analyzing oxygen consumption during mountain bike product development design.  

Q: Is VO2 Master scientifically capable? Can we run scientific studies with it? 

A: Yes, the VO2 Master outcomes are repeatable and valid for use in scientific studies. For more insights and information, read our validation studies and research. 

Q: What’s the degree of precision compared to a lactate meter to determine Zone 2? 

A: Lactate is a surrogate marker for shifting fuel sources during incremental exercise test protocols. 

In terms of “precision,” the two metrics can not be compared. 

The availability of glycogen and glucose to fuel glycolysis is just one factor that affects lactate concentrations. Measuring VO2 and respiratory dynamics shows a tester how the athlete is responding to the given task in real-time. 

If additional information like the Moxy Monitor is added to VO2 testing, we can see real-time changes in the physiologic response, and not have to rely on intermittent lactate testing.

VO2 Master directly measures ventilatory threshold breakpoints, and you can add lactate metrics as a secondary indicator to the report for confirmation. Simply use the “mark” feature in the free VO2 Master Manager app to add Lactate measurements and other manually collected data to the report.

Q: How does VO2 Master integrate with Moxy Monitor?

A: Please find the protocol for VO2 Master and Moxy in this YouTube tutorial. 

Q: Does VO2 Master connect to Garmin?

A: Yes. Here are the steps:

1. Connect your VO2 Master analyzer to the VO2 Master Manager app
2. Perform setup, including the appropriate user piece (M or L) and mask.
3. Do both calibrations (syringe and mask)
4. Disconnect the VO2 Master analyzer from the devices menu in the app at the bottom right side by toggling the button
5. Hold the Garmin watch, with the watch face displayed, right up to the VO2 Master analyzer.
6. When the device is connected, it will display “—“. When it isn’t connected, the VO2 Master data field will display “NC”.

Q: Can we use VO2 Master for swim training and testing?

A: Yes, you can use VO2 Master at the end of the pool to get readings, just ensure it does not get wet. Find the full details in this YouTube video. 

Q: How does the report determine limiters?

A: Physiologic limiters are based on the understanding that any given performance is a combination of the complex dynamics between the various physiologic systems of the body. 

We typically break these down into 6 categories:

1. Cardiovascular
2. Respiratory
3. Neurologic
4. Musculoskeletal-skeletal
5. Metabolic
6. Psychologic

By assessing all of these systems throughout a graded exercise test, one can determine limitations in one system and potential compensatory mechanisms in the others. 

The maximal exercise test provides all the standard graded exercise test metrics, including VO2max and the first and second ventilatory thresholds (ensure you have adequate warm-up and stages for the thresholds to be identified). 

However, the VO2 Master report itself does not determine limiters. To use the data provided by the testing equipment, a knowledgeable coach or physiologist must conduct an in-depth assessment. 

Additional sensors are very helpful adjuncts to VO2 testing alone, including Moxy Monitor, Core, HR, wattage, and cadence.

Q: When is the CO2 version coming out?

A: Our primary product development focus is the release of our CO2 version. Like many of our followers, we are excited about this release and have made significant progress on it. We do not currently have a release date to announce.

Our current VO2 Master Analyzer Kit reports: 

• Graded Exercise Testing: VO2 Max, VT1, VT2, Training Zones, HR, Breathing Metrics (Respiratory Frequency, Tidal Volume and Ventilation).
• Resting Metabolic Rate: Resting Heart Rate, Heart Rate Variability, Body Mass Index, Metabolic Rate %, Caloric Balance

• Download a Sample Performance Report
• Download a Sample RMR Report

Q: How accurate is the REE measurement if VCO2 is not measured? What formula is being used?

The answer to this question has a few facets.

For the subject receiving the report

VO2 is an indirect measurement of metabolism, and from this, we know how many calories one burns at rest.

For testing professionals/coaches/gym owners

VO2 has a 3.5x effect on RMR when compared to VCO2. It’s simpler to measure VO2 and assume an average RQ of 0.85 for VCO2.

The detailed equation

The Weir equation for RMR is: EE = VO2*3.9+VCO2*1.1. 

Then, this is converted from calories/hour to calories/day. 

The ratio of the coefficients is 3.9/1.1 demonstrating VO2’s influence and VCO2’s minimal influence on the equation. 

VCO2 and VO2 at rest typically bear a ratio of RER (RQ)  = VCO2/VO2 = 0.85.

The 0.85 average can vary from ~0.7 to 0.9 maximum range, with most RQ values falling between 0.8 to 0.9. This can result in measurement error up to 3% and 1% respectively. 

Now, adding VCO2 can theoretically increase measurement accuracy, but one must also consider the error contribution of the CO2 sensor itself. 

The most reliable way to calibrate a CO2 sensor accurately is by using a reference gas tank. 

When this procedure is followed, the lab carts are generally +/-3% accurate, thus comparable to VO2 accuracy. 

The derived error in RQ is computed as the square root of the sum of the squared error of each component:

%error RQ = SQRT(3%^2+3%^2) = 4.2% error.

The addition of an accurate CO2 sensor will increase the acuity of the Weir (RMR) equation but will introduce sensor measurement error comparably. 

The primary value-add of VCO2 measurements is in determining substrate utilization (fats vs carbs) on an RMR report.

Q: What about using a portable metabolic analyzer if you have asthma? 

It’s always best to check with a doctor before completing maximal exercise testing when there is a known condition. The VO2 Master should not restrict breathing in any way.