Using the MOXY Muscle Oxygen Sensor to Further Optimize Each Workout at Cycling Center Dallas

Moxy Monitor

I've written several unfinished blog posts about this topic, but each time that I get toward the finish, I end up coming up with something new to report, or change my mind about something that I see. The thing is, that the MOXY technology and what it tells us is SO new, that very few people really understand what it's telling us, what that means, how to use it, and why it may be important. That said, I've immediately begun to pick up on trends that I can see in real-time, that are giving me some pretty strong ideas about how the MOXY can help our clients get the most out of every single workout in the studio. This is a strong claim, but let me outline what I'm thinking, and then I'll be glad to discuss and debate.
Vastus Lateralis_copy

The MOXY Monitor is a device that is placed on the skin, under a cyclist's bike shorts, usually against the Vastus Lateralis. It's wireless, transmits in ANT+, and is picked up by our ceiling sensors, where it is read by our PerfPro Studio Software. The battery lasts about 90 minutes, and while the sensor can store data on board, it's really more suited for the studio environment, and of course, it's perfectly integrated in with PerfPro Studio and Analyzer.



The device transmits a beam of Near Infrared energy through a few layers of skin tissue and down in to the muscle, and there are two sensors that measure the reflected energy. The thing is sensitive to light, so it's best used with tight shorts, where it will hold its' position, or inside a special rubber blackout device, which is bulkier, but also works. Ubiquitous black bike shorts probably work best. Once it's on, you can't feel it, and it won't affect your workout.

Once the device is set up and paired to an athlete on PerfPro, there are two extra screens on the dashboard that relay the information to the athlete, and the coach. Furthermore, all of the information is save in .FIT and .TCX format, so you can upload it, and store it for analysis. The custom dashboard that I've created includes the following:


PerfPro Custom Dashboard
  • Per Lap Maximum Saturated Muscle Oxygen (Max SmO2)- This allows me to see how 'open' the muscle is. I can use that to determine a couple of things that I'll try to explain later.
  • Instant Maximum Saturated Muscle Oxygen (SmO2) - The rider can see where their muscle oxygen concentration is at that moment.
  • Per Lap Minimum Saturated Muscle Oxygen (Min SmO2) - We can use this value to look at the range of drop and rise between Max and Min, and we can also use it to determine a muscle oxygen plateau, which, again, is something I'm going to explain further, either in this blog or another.
Next to that, I've built a row that covers the following:

  • Total Max Blood Hemoglobin, given in mmol/liter, per lap.
  • Current Total Hemoglobin.
  • Minimum Total Hemoglobin per lap.
Then, on top of that lower row, I've put in metrics that are also important on a per-lap or per-interval basis. They include:

  • Target Load or Watts.
  • Current Power Output in Watts.
  • Current Cadence.
  • Current Heart Rate
  • Average Power Output per Lap in Watts.
  • Average Power Output per Lap as a % of FTP/CP, whichever you're used to.
Those of you who don't know how to train with wattage at the studio, basically, it goes like this...

The CompuTrainer puts a LOAD or TARGET wattage against the tire, and it's the job of the cyclist to MATCH that load with POWER. Since Newton's Third Law says that "Action = Reaction", the Target and Wattage are usually around 1:1, or, in other words, they're equal. When the body is placed under strain, you have to recruit more power to match the load, and this results in higher heart rates, and more oxygen required.

Until recently, we looked at Wattage as the outside, extrinsic result of force being applied to the pedals, and we looked at heart rate as an indicator of intensity from the inside. Adding the Muscle Oxygen Sensor, actually gives us another view, this time from the muscle's standpoint, and it's there that things get interesting.

Now, a LOT of what I'm going to say next is conjecture and educated guess, because you need to remember that I AM NOT an Exercise Physiologist. I didn't study this stuff that deeply in any academic setting. I've reached out to my better-educated colleagues, Dr. Conrad Earnest, Dr. Philip Skiba, and the esteemed Dr. Pete Snell, but let's face it - they're busy, and Snell is retired, so I really am on my own until the PhD's take over.

Based on what I have seen since I started using this thing pretty heavily in the late Summer of 2014, I THINK we can posit the following...

  • SmO2 and ThB values are as individual as Heart Rate maxes, mins, and wattage thresholds.
  • ThB Values have a fairly direct link to Maximal Oxygen Values, or Absolute Vo2max, in L/Min. The higher the number, the more you can thank your parents.
  • There's an 'Active Resting SmO2', where your leg muscles are sort of at half-saturation.
  • There's an 'Active Maximal SmO2', and 'Active Maximal ThB', which is best-obtained through a PROPER and THOROUGH warm-up.
  • Traditional warm-ups, where a cyclist rides at ever increasing intensities, on a rising scale of power, looking at perhaps heart rate or going by feel, are inefficient and perception-heavy. Proper Warmups will increase SMo2 to near-'Active Maximal Smo2' levels, and Near - 'Active Maximal ThB' levels. 
  • Once a Cyclist is at those optimal levels, intervals and workouts become MUCH more effective. 
  • This usually adds time to a workout, so plan accordingly. 
  • If SmO2 levels reach a certain level at wattage levels between 80 and 100% of Critical Power, and then plateau, that's a pretty good area for training for mitochondrial growth. 
  • If SmO2 levels reach a certain level at maybe 110-120% of Critical Power, and then plateau, I think that's a pretty strong sign of where to stay for more MCT4 development, or Lactate Shuttles. 
  • If SmO2 levels plunge, well, you're anaerobic and won't last long. 
  • Getting Smo2 levels down in to the teens or single digits can lead to some moderate micro-trauma in the muscles, which basically means that recovery is going to take longer, and you MIGHT be building more muscle as a result. 
  • We can use SmO2 values to determine the 'Recovery Window', or the best time for a cyclist to begin consuming recovery drinks and food, or, conversely, to begin other recovery methods, like massage or cryotherapy, etc. 
  • For asthmatics, I THINK we can use the Moxy to determine the best way to warm them up without triggering bronchospasms, and we can determine the optimal intensity to help them train safely and properly, given their limitations. 
  • I BELIEVE we can measure and quantify improvements in Mitochondrial Growth through the use of the Watts/Smo2/ThB combination empirically, but I'm not sure how best to go about it.
  • I BELIEVE that we can look at a Declining ThB, and determine a 'Bonk'. Seriously. THAT one I've seen.
  • I BELIEVE that we can also look at a Declining max recovery SmO2, and determine fatigue or a lack of calories, or even a state of dehydration. 
Okay - Once again, I'm hosed for time. I'll start showing examples of what I'm learning. I may even pull an all-nighter. We'll see. Until then, think about this...

If we have WATTS, then think of Total Hemoglobin as AMPS, and think of Saturated Muscle Oxygen Levels as VOLTS. I think it's apt.  

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