Wednesday, August 29, 2018

Hexoskin - review on the road

 Hexoskin - review on the road

One of this blog's main focus is the monitoring of physiologic data in the field while exercising.  To expand on that, I recently used the Hexoskin shirt on a road ride with the supplied software on an android phone.  As discussed previously, the unit provides consistent readings of heart rate, ventilation parameters and activity.  After the ride one can download the results and look at them in the comfort of your home (what I had been doing). 
However, as seen in some prior posts, the ventilation data correlates well with the MLSS, RCP and beyond.  From a practical standpoint, can we use this device to help with pacing, racing, testing in real time.  In addition, some sports (XC skiing), do not have power meters.  It would be potentially quite helpful to know your minute ventilation (after MLSS/ventilation calibration on a running test for instance) on the course for optimal pacing.
Off the bat, one downside of the Hexoskin is that there is no Garmin datafield, so no watch/cycle computer support.
All we have is the smartphone app which follows.

This is what the android app screen looks like:
This is blown up of course.

  • The screen will dim and turn off (no screen lock in your app) unless the time out is altered (and still not a real) fix.  The best I could do was a screen time of 30 minutes then it went to sleep.  Yes, it's a PITA to have to put a password in to get it back on.
  • Wasted screen real estate (see the top 1/3).
  • No full screen option (note the nav bars, notification bar)
  • For real time monitoring the font size is too small to easily read and the important metric of ventilation is not emphasized
  • The distance/time is not even needed since the user will have a bike computer
  • It would be nice to have a running graph on the bottom
  • No full screen option
  • No high brightness mode
  • No pause, laps
  • Difficult to press the tiny buttons with gloves, or while moving 
  • What happens in the rain - no screen lock
Bottom line - barely usable 

As an example of proper UI for functionality is Ipbike for Android:

  • User defined fields (data, averages, min, max, time spans)
  • User defined graph
  • User defined font size
  • Multiple screens possible (swipe across).  So different screens for different needs (whole ride vs intervals vs a max value screen)
  • Laps, pause buttons
  • Big buttons
  • Screen lock (for when it's raining)
  • High brightness and screen-on lock (no sleep)

Next gripe, Hexoskin data analysis:
If one uses the Hexoskin phone app, the bluetooth protocol is such that either the same or different phone will be unable to read the heart rate in another app.  So your Garmin watch, android phone (ipbike) won't pick up the heart rate while the Hexoskin app is communicating with the shirt.  That's ok and I realized the situation pre ride, but that meant that I did not have HR data in my ride file, it was in the Hexoskin file.
The problem with that is although you can look at the data on their website, their is absolutely no analytical capability there.  So no average HR during an interval which was what I needed.
However, the "help FAQ" mentions that you can export a .csv and work off that data.
Let's look at that .csv:
It's a mess!
There is valid heart rate data in there but it's also full of "crazy" values and zeros.  We could write a script to ignore the zeros but not the other values since they are occasionally close to the real ones.
In addition the ventilation is in different units (?corrected for weight and size) and multiplied by 1000 (?)
I am sure there is method in this madness, but "I'm a doctor, not a mathematician".  In addition, the end user just should not be subjected to this degree of user unfriendliness.

I did find a site called FitnessSyncer that will import the Hexoskin file directly from the parent web data (no download needed).
Here is the graph:

The problem is that you can't zoom, nor get averages (at least in the free version)

Next workaround:
Export the FitnessSyncer file as a .fit, then import that into my trusty site:
It seems that on a more granular level the "crazy values" are still in there.  In addition to the extra values, the time was off with the ride about 1 hour longer than it should have been.

There is also a program recommended by Hexoskin called Vivosense that can read the raw data - but it costs over 2000 dollars!  I downloaded a trial version and still failed at getting an interval average HR.  

Bottom line:
  • The Hexoskin shirt is a product with great promise but extremely poor implementation.  From my perspective, the potential usefulness of the data for endurance exercise is tremendous.  Unfortunately, the data interpretation is hampered as discussed above.
  • If you use the app, the ability to analyze the heart rate data is lost (except in view form). 
  • The app itself was evidently written by folks who meant well but never used it on a outside bike.
  • The Hexoskin web data display has very limited (really none) analysis ability.
  • No Garmin data fields for ventilation parameters, limiting it's use in running, skiing in real time. 
See also:
Analysis of Hexoskin binary RR interval and respiratory .wav data 

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