Fast Talk, ep. 70: Finding your strengths through failure, with Armando Mastracci

In episode 70, we discuss the compelling concept of finding your physiological strengths through moments of failure with the engineer behind Xert.

Photo: BrakeThrough Media

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The VeloNews Fast Talk podcast is your source for the best training advice and most compelling insight on what it takes to become a better cyclist. Listen in as VeloNews managing editor Chris Case and our resident physiologist and coach, Trevor Connor, discuss a range of topics, including sport science, training, physiology, technology, nutrition, and more.


The days when training software simply showed a power and heart rate curve are a distant memory. Whether you use TrainingPeaks, Golden Cheetah, or some other software, you’ll know that nowadays basic data is mined to reveal a wealth of information about your physiology, strengths, and training.

But, as soon as the software starts to interpret data, unavoidably, certain biases come into play. Perhaps better called principles, they are built into the software and any interpretations it performs. It’s not necessarily an issue, but it is important to understand the biases.

Most training software is based on biases that Coach Connor fully admits he would use if he was developing software. Created by coaches and physiologists, many training software developers knew what they were looking for and hunted for it in the data. One training package, however, stands out from this. Xert was created by Armando Mastracci who is an engineer first. While he came to understand the physiology, he started by simply looking for trends in the data instead of looking at the physiology. The result is Xert, a tool that has found unique trends which may seem unfamiliar to a physiologist but are certainly compelling.

At the heart of Xert is the notion of failure: the idea that we reveal our true fitness and our profile as a rider in the moments when we hit our limits at these points of failure. Armando will talk with us about how he was able to identify these moments of failure in athletes’ training rides, and then use them to create an athlete’s profile and help direct training.

But before we dive into the conversation it is helpful to define a few terms that are somewhat unique to Xert and this conversation:

  • First, Maximal Power Available. If you uploaded a workout to Xert, you’d see your normal graphs — heart rate, power, cadence, speed, and so on. What will be new to you is a line calculated by Xert called your MPA or Maximal Power Available. This is a second-by-second graphic of how much power you could produce. When you’re fresh, it’s equal to your sprint power. After a killer attack up a five-minute climb, it may not be much more than your threshold power. It is dynamic and it constantly changes over the course of your ride.
  • We’ve already mentioned failure — it’s that moment when an athlete can’t go any harder. In Xert, it is the moment when your MPA line equals your actual power — meaning you are going as hard as you can go. And if the rider beside you can go harder, they will drop you.
  • Finally, Peak Power, High-intensity Energy, and Threshold. All software packages have moved beyond FTP as the sole parameter used to define an athlete. TrainingPeaks uses a power duration curve. Neal Henderson talked with us in episode 33 about using five-second, one-minute, five-minute, and 20-minute peak power. Armando uses three parameters: 1) Peak Power: simply the power you can hit in a sprint when fresh; 2) High-intensity Energy: our capacity to ride above threshold, which is also often called Watt Prime; 3) Threshold: you know this as FTP. Xert uses moments of failure in rides and races to constantly adjust these three parameters.

Our primary guest today is, of course, Armando Mastracci, creator of Xert and owner of Baron Biosystems. He is the original brain behind these concepts, but he has also brought in respected physiologist and owner of Pez cycling, Dr. Stephen Cheung, to interpret these trends from a physiological standpoint, making for a more complete package.

Along with Armando, we speak with one of our favorite Fast Talk regulars, Colby Pearce, who needs no introduction. He shares his thoughts on this concept of failure.

We also talk with Brent Bookwalter, of the Mitchelton-Scott WorldTour team, about some of these new concepts.

Finally, we’ll touch base with Paulo Saldanha, owner of PowerWatts and coach of 2018 worlds bronze medalist Michael Woods. Paulo discusses lab testing in comparison to finding an athlete’s fitness on the road in slightly less structured but more competitive scenarios.

This episode is too good to fail. Let’s make you fast!

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