Could this sweat-sensing patch finally tear down the Wall?
Apart from the length of the shorts you choose to wear, there’s nothing more important in running than fuelling, hydration and pacing. Get any of these wrong on race day and you’re PB plans will be in the portaloo along with your high-carb breakfast. But as anyone who’s hit The Wall will tell you, knowing when to take gels, drink and picking the perfect pace can be a guessing game. Until now. One British company thinks it’s come up with a wearable that could revolutionise our runs and consign that Wall to history.
Enter Sweati, a groundbreaking, sweat-sensing patch you wear anywhere on your body, that uses small amounts of perspiration to read your glucose, hydration and lactate levels in real time, without the need to draw blood.
Old school lactate and blood glucose tests tend to involve turning a runner into a human pin cushion. A common lactate test protocol, requires you to run interval repeats at steadily increasing intensity and between each set someone draws real blood that’s then analysed in a lab. For blood glucose, the norm is a finger prick to get some claret onto a stick which is then popped into a reader to provide your blood sugar levels. It’s all a bit hurty and far from hassle-free.
What Sweati aims to do is offer the same information but without a needle in sight. Because sweat is a byproduct of blood, the theory here is that what you can measure in blood, you can measure in sweat. And Sweati says it has research to back this up.
In simple terms, if it works, this technology could enable you to spot if you’re well fuelled, optimally hydrated and running at a sustainable intensity to hit whatever goal you’re shooting for, be that in training or during a race. All continuously and in real time.
The non-invasive patch is the brainchild of James Mayo, a former international athlete, British champion and founder of SOS Hydration. Still very much in development, when we spoke to Mayo he revealed it could be 18 months to two years before his vision hits the shelves.
Sweati won’t be the first sensor to offer real time blood glucose monitoring either, existing monitors such as the Freestyle Libre already do this for diabetics. And Fitbit-backed Sano also offers real-time blood glucose monitoring.
But these tend to rely on interstitial fluid – found in the spaces around cells, coming from substances that leak out of blood capillaries – and still require fibres, albeit tiny, to be inserted into the skin and readings can suffer from a time delay. And none has yet offered the holy trinity of glucose, lactate and hydration in one solution, something Mayo is keen to highlight.
“We chose to use these three biomarkers together because in combination they’re more accurate,” says Mayo. “It’s all well and good having a glucose monitor but if you’ve got a glucose monitor and a lactate monitor together, the likelihood is that your lactate is going to change, if your glucose or hydration goes in the wrong direction. So each one acts as a trigger point for the other ones.”
Recent research done in conjunction with Imperial College London also confirmed that it’s possible to get hydration, lactate and blood glucose biomarkers from sweat with comparable accuracy to those you’d get using blood.
“In our most recent study, we compared blood glucose, to sweat glucose and to interstitial glucose,” says Mayo. “And we compared heart rate to lactate and also hydration to a protocol that we set up.
“What we got really excited about was that the blood and sweat glucose was a very close correlation. The sweat [readings] still had a bit of a time lag but this was three times faster than the interstitial. More importantly, the readings during exercise mirrored blood much better than interstitial,” he adds.
“Then from a lactic perspective, lactic and heart rate correlated very nicely. And finally with hydration we could see that after the person took an electrolyte drink or a high glucose drink, the readings changed.”
How will Sweati work and what will it tell us?
It’s one thing getting results in a lab, it’s another turning that into a reliable consumer product and the specific details of how it actually works are still very much under wraps. We don’t know exactly what sensors it’ll use, for example.
What Mayo could tell us was that it’d be a stickable patch that you’ll replace on a weekly basis, offering continuous readings of blood glucose, hydration and blood lactate levels.
It’ll be interesting to see how the company accommodates the sensors required to take the readings and communicate real time data back to a smartphone app or a watch, without them becoming bulky. The Freestlye Libre uses NFC to communicate but that is approximately the size of two £2 coins stuck together.
In terms of features, there will be two modes, a training mode and a health mode. Health mode will offer continuous monitoring of your day-to-day with alerts if you hit highs or lows for blood glucose, lactate or hydration.
In training mode you’ll be able to set Sweati to do a specific workout, for example a parkrun just below your lactate threshold, with live readings, alerts and a post workout summary. Athletes will be able to share data with their coaches who could spot in real time if one of their runners is experiencing difficulties.
Data could be stored and synced later for situations where running with a phone aren’t practical and Mayo assured us the aim would be to have it speak to a wide range of third party devices such as watches and apps.
Runners would be required to do occasional calibrations to get their accurate assessments of lactate thresholds but armed with these zones you’d be much better place to see your current capabilities, tailor your training plan more effectively to hit your goals and ensure you’re running in the right lactate zone to achieve your desired training effect, for example shifting your lactate threshold or clocking miles in the fat burning zone.
Come race day you’d also be able to use lactate as a guide to help you pace your race more evenly, a bit like you do right now with heart rate, pace or power which can be used as proxies for this.
You’d also be able to use the hydration and glucose readouts to know if you’re well-fed and watered before a race and when you need to top up during. No more chugging gels – or litres of water – ‘just in case’.
And that sounds like a very fine future to aim for.
