Anyone using a muscle oxygen sensor for complementing TR workouts

In general, I’d agree with that review.

Now, I don’t try to use the Humon in as “fine toothed comb” a manner as the reviewer – I look at the Hb and SMO2 levels after the workout in Garmin Connect (that data now uploads), and I’m still learning how to read those curves to get the most out of the information (the Moxy Forum and the information that Roger Schmitz has put out there are quite helpful).

The main use for me is “keeping the easy easy” – I see that occlusion and muscle tension can send me “into the red” quickly, so I’m learning how to dial back the easy even easier on post-weight training days, and learning how to pedal with more suppleness out of the saddle rather than goon-crushing it.

The other use has been in seeing what I need to do for work-rest ratios to see how to do some zone 5 indoors without as much “brain stress.”

I’m pretty stripped down with how I use it, and I can’t speak to testing because I don’t test. However, I do think it’s a gadget with some beneficial uses – what those are depends on how much of a data deep dive you want.

Soon after starting this thread, I ended up buying the Moxy. After using it for several months with a coach, I’m now back to using TR. I’m unsure if it’s my limiter or what, but the Moxy never really showed me that I was able to go for a hard effort. Anytime I went above 75w or so, the numbers would just go down. This made it so I was prescribed with super easy workouts to get Sm02 up. I lost a ton of fitness and now I’m trying to get back into shape for race season. I tried several sensor locations, etc… Unfortunately, there was a lot of promise here of telling you how your body was reacting to training stress, but this just wasn’t the case for me.

Here’s another interval session shot using the Humon.

I don’t want to put myself through 4min intervals at 115% indoors, so I’m trying some shorter efforts on 2:1 or 4:1 work-rest ratios – like 1:00 on, :30 off, or 2:00 on, :30 off.

This was 3 sets of 10 x 1:00 on, :30 off @ 115%. The Humon was “in the red” for the most of the last half of each set, and breathing/PE on the last 4-5 intervals of each set matched the sensations of the last 2min of a 4min interval.

It was a lot more work than a 4 x 4 or 5 x 4 – 30min worth of time at the target power. I’ll see what the results of this kinds of workout are in a few more weeks.

If these stimulate some good VO2 adaptation, they might be a case for using the SMO2 sensor to help pace the work intervals, and hit the right duration for the rest intervals, to log a lot of time in zone for Level 5 work.

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Ramp Test with SmO2.pdf (407.0 KB)

This is my first use of the Humon during a ramp test to estimate my FTP or LT2. According to the TR-Ramp Test I did a week ago, it estimated my FTP at 205 W. So, I designed this ramp test beginning with 50 W (yellow), increasing every 4 minutes by 30 Watts.

I found it very interesting how SmO2 (blue) behaves. When the power steps up I see 2 phases:
Phase 1: in the initial phase a decline of SmO2, which is due to a higher demand on muscle oxygen in respect to an insufficient supply. Then,

Phase 2: the body reacts to the increased energy demands by raising blood flow to the muscles (e.g. capillary dilation) resulting in an increasing oxygen supply and a change of direction of SmO2, now going up.

This pattern is consistent for all steps except at 200 Watts. Here in phase 2, SmO2 does not go up, instead there is a further decline which means that the body cannot increase oxygen supply fast enough to cover energy demands. Around the middle of the interval, SmO2 stabilises, staying approximately constant until the end of the interval.
At the onset of the 220 W step there is a further drop of SmO2, even more pronounced following the 230 W step. This means that increasing energy demands, which cannot be supplied by oxidation (maxed out) alone have to come from glycolysis.

Summing up, I would assume that my anaerobic threshold (FTP, LT2, VT2) is around 200 Watts, because it is at this level that SmO2 does not increase (phase 2). It is the level that I could probably sustain, which is also colored green (sustainable) by the Humon App.

At the bottom you see the humon color zones: Green (steady state): when the oxygen delivery and consumption in the muscle is balanced, meaning the athlete is training at a sustainable pace.
Orange (approaching limit): when the muscle begins consuming more oxygen than what is being delivered, meaning the athlete is nearing their body’s limit.

I would say Orange (approaching limit) is already crossing the limit, so being conservative, II would rather use the “last” green step (200 W) as my FTP.

I am really amazed how well Humon works. It shows the actual zones while training. I did also an interval session which was also quite interesting, that I will show later.

I hope you guys find this as interesting as I do and I am looking forward to more insights using SmO2.

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@jomu Thanks for sharing. I found similar patterns with now defunct BSX Insight. I can still use it via my Wahoo ELEMNT but the HUMON looks like a viable alternative

I’m not a bicyclist but I thought I’d respond to this. I hope no one minds.

ABOUT ME
I’m a 64 year old retired physicist who decided to get in shape to climb Gannett Peak (tallest mountain in WY) this past summer. It’s a 50 mile hike carrying a mountaineering backpack and a year ago when I decided to do it I didn’t think I was in good enough shape, so I started training. We managed the hike without any difficulty but didn’t summit as my wife had a bug she picked up from our daughter immediately before the hike. Anyway, as a result of my training I’ve participated in two foot races: a 50K and the Pikes Peak Ascent. I managed to complete the PPA in roughly what I had set out to (5:30-ish). During my training I did a LOT of LSD (long slow distance). I hike/X-xountry skied/snow shoed some 30-60 miles most weeks. In any event just after the 50K I purchased a Humon. I didn’t really know what to do with it. I personally think the color coding is useless. WHY?

ABOUT HUMON’S COLOR CODING

For starters the colors are determined by a a proprietary algorithm. For seconds what it reports is so far from reality for me that I pretty much totally ignore the colors. The Humon colors routinely tell me I am “in the red” (meaning I can’t maintain that pace) when I have a heart rate in the low 100’s. I can maintain my heart rate in the low 100’s all day. No matter what. Promise. I’m not suggesting the device is useless, just the color coding. Warm ups are particularly interesting. I am using it to warm up by taking it easy until SmO2 is up into the 70’s. Warm-up takes a bit more time than I would have expected without the device. During a typical warm up I’ll start off walking at a normal pace then speed it up, then jog a while and then go back to walking etc. SmO2 fluctuates during these efforts but trends upwards.

MOXY and Limiters

Recently my wife found the MOXY pages and I personally found them to be very interesting. For one thing, they think like physicists. (A good thing.) Their take is that there are physiological “limiters”. A physicist would talk about “rate limiting processes”. Moxy’s example is roughly the following. (I’m embellishing just a tad.) Consider an automobile production line. Say it takes 2 hours to build a car. An hour of that time is spent on bolting the motor in. Fifteen seconds of that time are spent bolting the bumpers on. The process of bolting the motor in is the rate limiting process. If you want to increase throughput you work on speeding up motor bolting not bumper bolting. Moxy claims that there are 3 key “limiters:” (1)Pulmonary (2)Cardiac and (3)Mitochondrial. So to improve performance you want to identify your limiter and then work on improving it. I don’t know if the 3 limiters that Moxy has identified are key or not, but they sound plausible to me so for now I am accepting them.

I also don’t know how much difference there is likely to be between the 3 limiters. For the limiter idea to be effective you need substantial differences in rates for the rate limiting processes. If it took 45 minutes to bolt the bumpers on, and an hour to bolt the motor in, (and 15 minutes for the rest of the car) even though the motor bolting is rate limiting, the bumper bolting might be considered low hanging fruit and worthy of attention. You fix the bumper bolting issue and now you’re down to 1:15 to build the car of which 1 hour is bolting the motor in. Now you tackle the harder problem of the motor bolting.

I’ve been using the Humon for a few months mostly as a toy because I didn’t know what to do with the data. Finally after reading the Moxy stuff I realized that my SmO2 does not drop much when I exercise harder. That suggests that my muscles lack sufficient mitochondria to power my muscles during sprints. So I am going to address that over the coming months by running intervals. One thing I tried yesterday was to keep my SmO2 above 70%. That was interesting. It was much easier than trying to stay in a fixed heart rate zone because the response time of SmO2 appears to be much faster than the response time of heart rate.

Humon’s color coding and notifications said nothing about my lack of dynamic range in SmO2. I think that at this stage of our understanding of exercise physiology the simplicity of Humon’s proprietary color scheme renders it useless. Using the SmO2 data takes a bit more thought than a naive color scheme can provide. As far as the device itself goes, I have no idea how accurate it is, but I am trusting that the data it provides is reasonably accurate. If I don’t get flamed for being a non biker posting on a biker forum I’ll report back in the spring as to my success/failure on increasing my SmO2 dynamic range and on my personal performance.

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There is a lot to unpack in your post, more than I have time for at the moment.

But for starters, where are you mounting the Humon sensor? If you haven’t discovered already, mount point is important. SMO2 is extremely sensitive to sensor placement. You can get different readings across different muscles or even on the same muscle body depending on placement. Ideally you will want to place it in the same location each time and over a major muscle being activated during said activity.

Hopefully, you have continued to use the Humon since Jan and acquired some new insights. If so, would love to read it when you have a chance.

I’m not sure of the names of the muscles but I usually mount it on the front center (left-right) and about 1/3 of the way down from my crotch to my knee. Recently I’ve tried mounting it at about the same vertical height but on the outer left side of my left leg. I don’t see much variation in the response.

So under your bib shorts? All pictures on their site shows them mounting just above knee below the shorts. I was wondering how it would be mounted higher under the leg sleeve of my shorts.

When we moved, that little box got lost. I may get another, I may not.

I wear it about where the guy in the picture on this webpage has it. https://www.humon.io

I wear longer shorts so it is covered. My wife wears it below her shorts uncovered. It seems to work either way.

The past few days I’ve rotated it about 90 degrees to the outside from how the guy in the picture has it. It seems

to give slightly higher readings that way but I don’t think there are any major differences in the trends. I think

Moxy might recommend placing theirs on the outside of the leg instead of the front.

Just recieved the humon hex I bought 1 week ago. Did two Training ride with it, and I am pleased with it so far.
It is still very earlier but my analytical brain is very excited to understand more. I see very interesting insight to dig into.

I hope that TR and other plateform will incorporate it in their displays.

I am using one as well. I have the value ( smo2) displayed on my wahoo computer as well as on the humon app on my phone. It seems Chad’s workouts generally keep me out of the red zone. Do you hit red often? I haven’t gotten higher than 82 on the humon rating.

I agree thought that it would be nice to have this data displayed on the TR app and career stats.

Do you know if there any way of using it to determine accurately your power / HR at LT1?

I just did two endurances exploratory ride, I will not be starting SS1 until Feb, so too early to say. For now!

I think yes, per their protocol:
https://support.humon.io/hc/en-us/articles/115002909454-Use-Case-Incremental-Threshold-Test

Did not try it yet, so I can not evaluate its accuracy nor consistency.

That test appears to pinpoint LT2 . However LT1 may be just before SmO2 starts dropping?

You are correct - I read too fast. I remember, though, reading something about LT1. If I find it, I’ll post it.

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For everyone using the Humon, have you made any adjustments in your training because of it? If so what?