Humon Hex Review ⬢ Muscle Oxygen Use-Case Scenarios

Humon Hex Review

This is a Humon Hex Review - the Hex is a muscle oxygen sensor and this is a user review explaining my experiences as well as talking about the device and technology that supports it. I also pay particular attention to some use-cases and workouts I performed with it.

Humon Hex Review

SmO2 : Why Bother?

We have power and we have heart rate, both of which we can use to determine FTP and LTHR respectively and then subsequently set training zones and racing efforts. But power is telling us what our body is achieving, not necessarily what it is having to do to achieve it. 400w for 30 seconds is much harder when you do it a second time.

Heart rate is a measure of what is going on inside the body but it's not really telling us how hard we are working specific muscles. It's perhaps more of a lagged, systemic indicator of output that is subject to various physiological vagaries. Plus, if you look at how you determine your LTHR then you would probably find that different ramp protocols would give you different answers. You may also find that repeatedly performing one protocol on one day would yield apparently better lactate curves as the day progresses to the point where, in the final test, your lactate curve could be the 'best' yet your performance, in watts, would likely be the worst.

By measuring muscle oxygen we can look at the steady-states, highs and lows of the oxygenation levels achieved as well as the rate of the accumulation and depletion. These insights can be used to manage workout intensities, monitor recovery and muscle fatigue.

With muscle oxygen I was particularly interested in:

  1. Seeing how my body coped with extended periods of endurance bike riding
  2. Assessing how well I normally warm up when cycling and how to improve it.
  3. Looking at the stop and start points to optimise short bike intervals
  4. Re-visiting a muscle oxygen tool for endurance athletes and updating my experiences there.


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25 thoughts on “Humon Hex Review ⬢ Muscle Oxygen Use-Case Scenarios

  1. Interesting review. I assume every example was for cycling.
    Have you tried to run or do strength training with this device?

    • yes it is mostly for cycling.
      I do roughly equal amounts of cycling and running training. however I find cycling a more ‘controlled’ environment.
      I HAVE done 5 or 6 runs, maybe more – i forget, and the overall picture seems similar. the MO figures are different.
      I have not used it for weights at all.

      • Do you find that it holds its position well while running? I think I’d probably feel safer wearing it under half tights.

        Also, how would you compare it to the BSX Insight? I found the BSX was pretty finicky in pairing with a watch and it seemed to freeze a lot. I was never able to do a full lactate threshold test with it because I didn’t have access to fast enough treadmill 🙂

        • not quite as good when running. i shoudl have mentioned that. i DO normally wear long tight shorts (half tights) so it is zero problems with them.
          i’ve included the tips on how to pair with a watch, the prob is pairing with the app AND a watch, that can be a PITA until you know how.
          longevity…i mena i’v eused it for 8+ hours of cycling …maybe 90-120 minutes as a single run?

  2. Regarding the BC W/U protocol. I used their plans in TP and this is FTP % they assign to their structure workouts in TP.

    5m @ 45% FTP (90 RPM)
    2m @ 55% FTP (95 RPM)
    2m @ 65% FTP (100 RPM)
    2m @ 75% FTP (105 RPM)
    90s @ 85% FTP (110 RPM)
    30s @ 100% FTP (120+ RPM)
    2m @ 45% FTP (90 RPM)
    6s @ 105% FTP (Max RPM)
    1m @ 45% FTP (90 RPM)
    6s @ 105% FTP (Max RPM)
    1m @ 45% FTP (90 RPM)
    6s @ 105% FTP (Max RPM)
    2m42s @ 45% FTP (90 RPM)

    • thank you Tomas.
      yes I used to have a BC FTP-based warmup. I was surprised to find one based on rpm.

      I’ve been experimenting quite a lot with warmups. so i will try this (perhaps tomorrow) and see what Humon shows.
      what I am finding (for me) is that when I have reached peaked oxygen saturation I just might be a tad too much over-exerted. but i’ve also found that I do need a 20-30 minute warmup (the one you supplied is 20 minutes) so I’m keen to try to keep the warmup as short as sensible

  3. Hi 5K runner,

    I recently bought and used the Humon Hex. My experience with the device is somewhat different than others. I have a relatively normal SmO2 at normal pace (60%, max 68% when stopping and 14.4 gramHb/dl). But when doing sub-lactate threshold intervals (in the range of 3:45-3:30/km @ 160-173 bpm) my SmO2 values drop quite a bit more than I have seen with others to around 36%. I am sure that the intervals are ran below my Lactate threshold due the experience of my trainer and the results which have led to that conclusion (based on Stryd power, first beat technology, 5K results of 16:40 and a recent 8K cross, PB at 1500m at 4:15,86)

    I see a lot of people already stop at 50% during intervals and say that they reached LTHR but I am not yet convinced because ofcourse I experience the initial drop of SmO2 to the low level to after see it stabilizing, this requires almost two minutes, then I continue for another three minutes to take the recovery time of around 50 secs to almost completely recover. I think only a exhaustive testwith 3-4 laps of increasing paces can prove such a threshold reliably.

    So I have yet to discover that supra threshold the SmO2 cannot stabilize and will drop to exhaustion, due the Bohr effect (acidosis induced release of O2 from Hb) it should be able to get very low. Furthermore I might have little adipose tissue aiding the measurement according Humon’s validation article with the MIT.

    In the light of this and maybe further experience from your side what is your (current) take on using the Humon Hex for LTHR determination?

    • IIRC Humon claim to have validated HEx to within +/-5w of LTHR. I’m not entirely sure about lt2 determination across a range of conditions

      my personal data is similar to how you describe your data.
      doing what you describe my sm02 could be a little higher than you during exertion and i’m not entirely clear on what happens close to exhaustion
      my time to recovery is probably at least 3 minutes too.

  4. I will add a comment: for biking at least, if the Hex is on your thigh, it can show you entering the red if you move around on the bike. For example, mountain biking when you stand up to use your legs as shock absorbers while you descend, at least for me, oxygenation can precipitously drop from green to yellow and then deep red, and then arise again when you go back to pedaling normally.

    Not necessarily saying this is a bug–after all, it’s clearly showing something that’s going on in the muscle–but it’s something to keep in mind when interpreting what you’re seeing, pacing an endurance ride or doing the threhsold test (i.e. don’t move around while doing the test).

    Good post though

    • i have occasionally noticed similar (yesterday actually).
      there could eb two things at play
      1. vibrations causing the sensor to not be able to properly make the readings.
      2. extended period of descending might give unexpected results if standing and not relaxed.

    • Our users have been using the Hex to detect overtraining for some time, and we have been working on features to accommodate this. As the Hex is essentially measuring the exertion of the muscle, the data provides great insight here. At the end of an activity, the Humon App will look at, among other things, how much time you spend in the red zone, and how well you recovered from bouts of effort and quantify your approximate effort level on a scale of 1-4, as well as provide some textual feedback to help understand the data.

      Some of our super users have been able to go quite a bit beyond this by understanding from previous sessions how their body should respond, and adapting when it is not responding ideally. I hope this helps!

    • you’ll have to ask Mr Zwift that one…I suspect it’s low on their list.
      Humon and Moxy broadcast a standard signal so it’s up to the receiver to receive it.

      thank you for the support..USE THE CODE !

  5. Hi Great and comprehensive review. One thing though that I couldn’t find was whether or not it was possible to use it to determine accurately the Aerobic Threshold (VT1/LT1). Thanks

    • i asked a similar question quite a while ago and got this: “There is nothing really to discuss on Humon’s ability to accurately determine LT1 yet. The Hex has been clinically validated by Harvard Medical School in its ability to accurately correlate with LT2 (4 mmol/L lactate). When completing the incremental test, when entering the red zone is where your LT2 pace is”

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