Friday, April 13, 2018

"Humon" muscle O2 sensor review

DIY ramp testing

It was with great excitement that I followed the press info, development news and release of a new muscle O2 sensor from a company called Humon.  The Moxy is a great device with a huge consumer base but has not been modified in many years.  BSX is smaller, lighter, less expensive but the company is basically past history.  My hope was that the Humon product would address several issues.  First, provide solid peer reviewed independent (not done by their advisory board members) studies showing that the sensor would benefit training, race pacing or recovery.  I was also hoping for something even smaller than the BSX, perhaps in the Polar OH1 range in size and weight.  In addition, the sensor should be easily movable to other body areas during a weight training session, or even changing the site during a ride without re-calibration.  A strong Ant+ signal is mandatory especially with some products like a Garmin Fenix 5 (weak Ant reception).  In addition, compatibility with some Ant+ head units that may have older muscle O2 protocols or need the speed/cadence sensor workaround was expected.  I am not a fan of the smartphone app being integral in the start stop and monitoring but if you are going that route, hopefully the app with show some details (second to second detail). 

Did we get any of this?

Preface: This review is going to be a bit different from some, but I am coming at this from an alternate use case perspective.  The unit is designed for the rectus femoris (at least the study was done at that spot) so I guess my use is out of their spec.  However both BSX and Moxy are able to be used on alternate sites.

Company Hype- Well we did not get anything unexpected from the "claim" standpoint.  More non substantiated claims of better recovery, pacing and warmup.  How this is an "AI" coach is beyond me.  But since AI is the new catch phrase, why not claim it.
 

They do quote a white paper which also has some references but they have nothing to do with pacing, recovery or warm up.
What is also disappointing is that their peer reviewed study was done by a board member who presumably has a financial interest.  That is a big no no in my field (medicine) and sets off red flags in my book.
It's open access so you can read it:

 
 

Note that the study is only a validation of using this for lactate thresholds which has been shown for Moxy and BSX already - so nothing ground breaking here.
Certainly nothing backing up the claims on the website.

 Ant+ strength-
This is a major problem for me.  I noted severe signal loss and data drop outs if the sensor had a body part between it and my Fenix 5.  Now, as I mentioned the Fenix 5 is finicky but never this bad, verging on unusable with this device.
I could not get my Samsung Note 4 running Ant+ plugin sampler to find the device so the digital signal could not be compared numerically to the BSX.
However using the Fenix 5, BSX side by side with the Humon sensor, no obstructions with line of sight, the watch lost signal at 9 feet with the Humon, 18 feet with the BSX.  

 Here is a use case example.  Watch on R wrist, BSX on lats (signal must pass through body), Humon on R deltoid (signal line of sight or through wrist worse case).  Three sets of posterior deltoid (rear fly).  A couple of minimal dropouts on the BSX but the signal needed to traverse my torso.  The Humon had many dropouts(not usable) even though the signal path was 2 feet and line of sight mainly.  I did note that if I just had my wrist in the path, the watch would not read the Humon sensor.

  

What about my pet project of Costal O2?
A couple of issues.  It appears that the Humon needs to go through a calibration phase after turning it on.  It is physically hard to push the buttons to turn it on with your Skins shirt, light blocker over it.  The tracing below was done turning it on with the app on my Pixel 2.  It is displayed on Garmin Connect.  The BSX started about 80% and dropped to 38% or so on a 3 min ramp (340 w avg) on the L chest pectoral area.  Humon did not do too badly, baseline near 50% and dropped to 2-3% at the costal area.  But I was concerned with the wavering readings and drop out after the interval


 Here is a 1 min max (540 w):

The Humon does track the costal drop well, but again weird spikes (lasting multiple seconds) after.  Perhaps motion affects the Humon more than the BSX (but I was moving less if anything).


The android app is also limited in that you can't zoom in on segments (at least to my attempts).  Here is my tracing on the app: