Interested- yes. To what level? TBD. I like data and new ways to look at things but it would need to offer something all these other systems don’t. Is it more reliable, cheaper, overall a better indicator, application outside of sport, etc.

I’d definitely want to hear more about it.

So essentially the current model is an armband similar to a compression sleeve, but with a small sensor embedded that has four components:

1. An array of all the typical sensors in most recovery wearables - heart rate, skin temperature and blood oxygenation (not shown on diagram below)
2. A microfluidic sensor that continuously measures cortisol levels through sweat in real time (we are all sweating at low enough baseline levels that the particular base layer of our sensor can wick enough of this base level of sweat to get a continuous measurement). Because we are measuring continuously and we have designed the wearable to be comfortable enough to hopefully be worn 24/7, especially during sleep, we think a chronic cortisol measurement is a much better metric of that elusive knife's edge between training to the point of functional overreaching and getting faster and overtraining.
3. A bluetooth module for sending all the data to a smartphone app that displays data and gives alerts when metrics are outside of the individual user's baseline
4. A series of Pettiler plates that automatically cool the user down when a metric of acute stress gets too high. This is really more geared towards the use of the device in the treatment of PTSD and panic attacks.

A lot of the value offer derives from the fact that the hallmark equation in gaining fitness is the right balance of activity and recovery. Power meters, watches, activity trackers, etc. give us really good data about the activity component of the equation, but the recovery metric lacks accurate data. Really, the metric that is touted as the gold standard of recovery - HRV - can only accurately be measured using a heart rate strap, which most people aren't willing to wear 24/7 (shown on the market map as low on the comfort axis). In addition, I (and others) have doubts about how useful HRV is in isolation. It is skewed by so many different metrics, especially in women, due to the menstrual cycle, that it just isn't the be all, end all of training readiness that Whoop and Oura use it as. HRV is also a lagging metric - if our device works the way we think it can, it could actually be preventative of overtraining rather than detecting it several days in. We think that there is a lot of value in that.

So, in short - we are hoping to fill the upper right quadrant of the market map with a combination of a discrete and comfortable wearable that has better data accuracy. And yes, I do include MVDP in the pitch deck to make the point that he doesn't trust whoop data on his bike :D

I’d be willing to wear 24x7 (swimming?) and do agree that, while I look at HRV and Oura’s other metrics, it’s only rarely told me something I didn’t already know. Meaning if already gone to that place and at best it just keeps me from going further. Nothing to prevent.

The graph didn’t show correctly on my phone so maybe I missed something critical.

But I’m intrigued. How close is the product to market? And cost point?

So right now, it couldn't be worn while swimming. We are looking to have a minimal viable product by the end of August. Aiming to come on the market in Q1 2023 at $249 for hardware and $11/month subscription. Thoughts?

Personally I’d prefer no subscription but ~$250 range is “in play” and it’s not a hard no for subscription but would be a bigger hurdle for me to pull trigger.

I like to quickly forget how much money I spend on things I really don’t need… subscription just reminds me of that.

So the reason for the subscription is twofold - (1) Helps with a startup as investors love that monthly recurring revenue and (2) the cortisol sensor will need to be replaced about once a quarter- very simple- we send you a new sensor that you slip out of the pouch on your band and insert the new one. But it helps us cover the cost of the lifetime use and allows us to incentivize users returning the old sensor to us for a discount so we can make sure the electronics are properly disposed of and the recyclable components can be reused.

Asking from your friend (or anyone else). Is there good evidence that cortisol levels through sweat might be an "accurate and robust" indicator of overtraining?

Because - and this is just me (n=1) - cortisol blood levels don't appear to correlate.

Like I'm in a *bad* overtraining hole now. To confirm it, I updated my (crazy expensive) InsideTracker metrics.

Hematocrit and hemoglobin significantly down. (though iron levels slightly high)
Testosterone flirting with official hypogonadism levels.
Inflammation up.

But cortisol smack in line with my previous three tests (~1 per year), and in the "optimized" zone per InsideTracker's criteria.

Whoop did f-all for me. It thought I was doing great all along.

That’s justifiable.

I assumed all that would flow with product release and the marketing material.

If the research is proprietary maybe? But I'd doubt that a startup-type organization would have the resources for internal, high-quality trials.

I was hoping someone would have some knowledge of public-domain research pointing in this direction.

Not a big believer in "product release/marketing." If you were to read Whoop's marking, you'd think it had a rock solid basis. But the scientific consensus for HRV as an overtraining indicator is, I believe, mixed at best. On my Whoop, I'm finding that nighttime resting heartrate appears more reliable than HRV.

Agreed.

Whoops, additional as best I know, refused to validate against the “gold standard” so even their ability to measure and predict could be argued- atop of what’s measured being valuable.

I need to see some robust backing before my money goes to another start up after living through a couple iterations of BSX blowing up and taking everyone's money.

First, I'm sorry that you are suffering with overtraining right now. It absolutely sucks.

As far as your experience with you blood cortisol levels being smack in the middle of normal - I'm not surprised. It has been shown that basal levels of cortisol are not altered in response to overtraining (https://www.ncbi.nlm.nih.gov/...articles/PMC5541747/) - what we would be measuring, and where we think the value lies is continuous cortisol response throughout the day. There is some good evidence that cortisol awakening response is altered in reponse to overtraining in healthy athletes (https://pubmed.ncbi.nlm.nih.gov/33662935/).

We're still building out our first model, but we have a trial set up for the fall with semi-pro cyclists to generate some more definitive data. Right now, we are really wondering IF we can validate that chronic cortisol levels measured through sweat track well with other well-validated indicators of overtraining (e.g. lowered testosterone, blunted GH & ACTH response) AND IF we can validate that our device measures chronic cortisol levels accurately (validated against blood cortisol levels), would this be something that people would be interested in?

So would you need to be actively sweating for this measurement to be made?

(Edit: didn’t throughly read your explanation about baseline sweat levels, ignore that question)

I’m pretty interested in this as someone who is interesting in recovery and is utilizing microfluidics heavily in my PhD. Without giving away any proprietary info can you tell me more about the microfluidics? How much volume do you need? Do you measure cortisol via staining? Are you channels made out of glass or plastic or (hopefully not) PDMS?

Any relation to this journal article?

Anal Chem

. 2022 Mar 1;94(8):3526-3534.
doi: 10.1021/acs.analchem.1c04508. Epub 2022 Feb 16.
A Portable 3D Microfluidic Origami Biosensor for Cortisol Detection in Human Sweat
Xuan Weng 1 2, Zhuoyi Fu 1, Cheng Zhang 1, Wen Jiang 1, Hai Jiang 1 2
Abstract - Analysis of cortisol levels in human sweat is increasingly important as it can be a "stress biomarker" in stress-related disorders, giving real-time information about human health status. In this study, a portable 3D microfluidic origami biosensor based on a smartphone was developed for cortisol-level detection in human sweat. Molybdenum disulfide (MoS2) nanosheet-mediated fluorescence resonance energy transfer (FRET) and fluorescently labeled aptamers were employed in the biosensing process. A multilayer-structured 3D origami microfluidic chip was fabricated and functionalized to facilitate low-volume perspired human sweat collection, transportation, and detection. The translatability of the biosensor was exhibited by the fluorescence analysis in a smartphone mounted in a custom-designed holder. The critical design parameters of the microfluidic origami biosensor, including the characterization of various paper substrates, the concentration of MoS2 nanosheets, and the incubation/reaction time, were adjusted to obtain an acceptable range for the assay dynamic range and limit of detection (LOD). Under optimum conditions, various doses of cortisol within the physiologically relevant range of 10-1000 ng/mL reported in human sweat were tested to evaluate the performance of the proposed biosensor. It displayed an LOD of 6.76 ng/mL at 3σ in artificial sweat, an analysis time of 25 min, and high selectivity. The performance of the proposed cortisol sensor was compared with an enzyme-linked immunosorbent assay (ELISA) for a spiked artificial sweat sample, and a correlation coefficient of 0.988 was found. The proposed biosensor also presented satisfactory results in the determination of the cortisol levels in a real human sweat sample. The resulting portable biosensor provides a rapid, low-cost, convenient, and non-invasive sensing solution for the point-of-care analysis of cortisol levels in sweat.

Hey - thanks for the question! Our current strategy for gathering cortisol is a wicking hydrogel, rather than a proper device done by lithography (as you know, if we make of those out of PDMS, it won't last very long with the friction of the skin/device interphase). Then we measure cortisol electrochemically.

Functionally, they are trying to do the same thing, but our base technology is different. They are selecting for cortisol using aptamers, where we use molecularly-imprinted polymers (MIPs)