Anyone using a muscle oxygen sensor for complementing TR workouts

I was looking to see if anyone is using a muscle oxygen sensor such as the Humon or Moxy to help with training. If so, has it helped? Humon seems to have good software around it, but it isn’t really integrated into a training platform.

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@sdang I regularly use the Bsx Insight along with my workouts. More informational at this point but also for recovery purposes. Have not tried either of the other two devices however.

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I own a BSX, too. Haven’t used it in quite a while, never really found any use for it in training. Liked the threshold test but it was a big bummer for when they silently dropped the LT1 estimate and just reported 75% of LT2. This was actually the main reason why I got one. And now with the entire company having gone down, early adpoter risk I’d say. The LT2 testing worked pretty fine for me, there was always a good match with 0.95xCP20

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@sryke I agree. It was great for finding where to anchor training. I am a horrible at pacing and found this was so much better. Now with the ramp test on TR I don’t have to worry about it. I did find it easier to use with new athletes or less experienced ones to determine “FTP” for anchoring their training since doing the regular ftp testing can be problematic when it comes to pacing for inexperienced athletes.

So if using the TR Ramp Test, what would approximate LT1?

(caveats: yes, it’s variable, yes, it’s individual, and yes…you know, the usual caveats around not actually using a blood measurement of lactate to estimate a threshold for—wait for it—lactate :smile: )

I’m following the Polarized discussions on this forum and the podcasts fairly closely, so I’m familiar with the power and heart-rate based derivations.

But I haven’t seen anyone say: “so in the ramp test, it’s when you get to THIS power or THIS heart rate”

For me TR Ramp Test does not even approximate LT2.

For AeT & VT1 the good old breathe test?

I doubt it does mine either.

Ok, this seems fairly straight forward (and I appreciate your pointing me in this direction). Quick follow up: which TR “workout” would you load. I’m assuming I would need to do this in manual mode (not ERG mode). Just “Free 120” or whatever they’re called.

yes, these Free workouts seem to be appropriate.

Still have PerfPro on my cave-PC, would probably use it for this. Or control the Kickr through my Bolt.

I wonder if TrainerRoad will incorporate the data fields into their UI. It would make it easier to see the data.

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well, you can always run a Wahoo/Garmin in parallel.

However, the problem with BSX was that SmO2 changed only very minimally in magnitude. In real time it was difficult to detect changes. Post-workout analysis was possible when zooming into the data. That’s where you saw the patterns. Though, as already alluded to above, I failed to gain any meaningful understanding from this additional data.

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I took it a step further and just made my own ramp test. 5 watt increments every minute. Ended up saying the US Pledge of Allegiance a ton and voila—poor mans VT1.


@sryke I would concur that there are typically only very small changes if you are doing lower intensity steady state activities but it’s very noticeable when you do higher intensity intervals at threshold and above. That was originally what it was designed for. Find your lactate threshold, train at it, and then also use those SMo2 levels to determine when one is recovered within and between workouts.

I don’t think these sensors make any sense for cycling. There are multiple calf muscles and the one the devices look at both bends the knee and points the toes down. Where in the pedal cycle do you do this combination?

There are deeper muscles than are far more likely to be of use and likely to get hypoxia earlier. Only at high levels of cycling is the muscle these devices look at going to be much used (as it also requires extra quadriceps force to counteract the calf effect, which may already be tired).

I’ve seen studies where they looked at the inner part of the quadriceps muscle instead. That makes a lot more sense, although you could still argue that with a good bike fit there are better muscles than a part of a muscle whose primary aim is to stabilise the knee cap. Are you able at all to migrate the sensor to a more sensible muscle at all?

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@eerke most, if not all, (including bsx insight) of these devices can be used on any muscle group.


That is impossible. They use light, which is absorbed and so the sensors are limited to only superficial muscles. The only way I can see for them to see deep muscles is if they are surgically implanted and it seems unlikely anyone would go that far.

The ones I saw in photos had a holding mechanism that seemed calf specific. Do the kits they come with help with alternative placements so they can see more sensible muscles?

@eerke my apologies, I should have been more specific. It can be placed “ anywhere on the body”. While the bsx insight does come with a sleeve, it could be placed anywhere as long as it was set up so outside light was not able to interfere. The thigh with a neoprene thigh wrap etc. This is the same with Moxy etc. Some research was done for example while using rowers and placed on both the quad and the biceps.

The bsx insight was actually shown to be within +/-2% accuracy while on the calf in cycling by the Australian insititue of sport research project and was subesequently published. A few other research projects also found the same thing. So, sensible or not, it was adequate at doing what it purported to do.

there’s an interesting article on the Humon Hex in the link below.

This device only useful in post exercise analysis? or can it be used dynamically while you’re exercising?

Based on its color coded alerts i am wondering if used for HIIT one would see increased improvement delaying their next interval until adequately recovered

I hesitate to comment on this thread because I don’t have a dog in the fight…but I did recall an interesting presentation that Coggan did summarizing the work he did with the Moxy NIRS device. I thought there were a lot of interesting conclusions that you could glean from his data that had value on their own regadless of how they reflected on NIRS as a training tool.

Anyhow, to me that presentation made it clear that NIRS might not be most applicable to cycling. We already have tools to help us find thresholds in cycling (although NIRS was just as good as those!). However, as Coggan mentions during the presentation, NIRS might be more applicable in other activities that don’t have power meters!

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I started using a Humon this week. The color-coded zones seem like they could be practical for helping reinforce “intensity discipline”: blue, recovery; green, steady-state endurance at/below LT1; orange, between LT1 and LT2; red, at/over LT2.

In their ramp test (which I have not done), LT2 occurs shortly after SMO2 is “red zoned.” I don’t do tests (I go by feel and look at HR and watts descriptively, not prescriptively), but I’ll see how the color zones react to some hour of power rides. I suspect that what I’ll see is about 45-50 minutes of orange and then a kick into red at the end (there always seems to be a hammer that drops sometime between 45 and 50min, depending on my fitness – watts stay the same, but that last 10-15 is, as we know, rotten-feeling).

The green/orange transition looks useful for keeping below LT1 on endurance days – only one workout so far, but in what was supposed to be 90min at 280w (around 80% of FTP), I started going orange for a minute or two, every 4-5 minutes after the 60 min mark. HR was stable, power was stable – if I was just using those, I would have finished off the 280w even though the last 15min may have not felt comfortable. I backed it down to 270 and it stayed green for the last 15min.

It’s possible that such little adjustments down, rather than pushing through (even at a low HR – I was at 74% of HR max, 65% of HRR), might keep fatigue down and be a smidge more effective in “raising the floor” during endurance sessions.

I think there’s a use for this – power says what work you are doing, whereas SMO2 says what your body is doing to do the work.

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I don’t know anything about the Humon but maybe you can comment on the validity of the points in this review.