Let's talk about sweat: We tracked hydration with the Gatorade Gx smart patch

Can a smart patch help you make better decisions about your hydration?
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When a wearable says it can track your hydration, that usually means manually input each time you lift a glass of water to your mouth. But the Gatorade Gx is a little bit smarter than that.

US sports drink giant Gatorade believes it can deliver those insights via a wearable patch. You scan with your phone camera to get recommendations about your hydration and recovery strategy.

The Gx Sweat Patch has been in the works for over three years and has been backed by studies that stretch further much further back to help bring into this wearable patch form. It's a single use patch that captures sweat, then analyses the unique biomarkers within it to offer hydration recommendations based on that data. The idea is that if you know how you sweat through exercise, you can better understand how to recover and prepare for before taking on a similar session.

At $24.99 for a pack of two patches, this stick-on wearable doesn't come cheap. The question is, does it work and can it help to make smarter decisions about how to recover and refuel after exercise?

We've been putting it to the test indoors and outdoors for rides, outdoor runs and home workouts to find out if this smart sweat patch is the future of better understanding your hydration needs.

How the Gatorade Gx smart patch works

Let's talk about sweat: We tracked hydration with the Gatorade Gx smart patch

The GX setup was created by Epicore Biosystems, which created the sweat microfluidic sensing platform that patch is based on.

That studies the control and manipulation of fluids and is related to processes like DNA analysis.

It's not the only hydration tracking wearable out there, and we've previously spent time with the Aura Apple Watch strap, which estimates hydration levels via a bioimpedance sensor on the wrist.

Epicore Biosystems teamed up with Gatorade to translate its athlete testing from professional teams to bring these insights to the masses. To better understand what sweat tells them about how to hydrate to improve performance.

Matt Phanke, Gatorade Sports Science Institute’s principal scientist, told us numerous research studies were carried out to understand the best location for the patch to offer fluid loss for the whole body. It looked at multiple locations, but felt the inner arm provided the best place to translate fluid and sodium loss for the whole body using software algorithms its team developed for the platform.

Wearing the Gatorade Gx

The patch itself looks a bit like a medium-sized plaster, which uses a hypoallergenic adhesive to keep it secure on your skin. It has to be worn on the inner of your left arm, a few inches above from your elbow crease.

There's no electronics involved here whatsoever, so it's really about making sure you work out for long enough and wear it correctly to see those areas in the patch start to fill up with the colored dyes.

The idea is to use the patch for high intensity workouts with Gatorade recommending workouts like cycling, running, football, basketball, tennis and lacrosse.

Your tracked activity needs to last at least 30 minutes and not exceed 2 hours. You should also be in temperatures ranging from 47-95 Farenheit (7.7 to 35 degrees Celsius).

That is to ensure you can get a good sweat on so the patch can capture it and then mixes it with a food dye that fils the patch with orange liquid and purple liquid. The orange section relates to your sweat rate and the purple for your sodium loss.

This patch wants to show you how much you sweat and and record sodium loss while you sweat to better analyse how you need to recover and refuel. Crucially, you don't need the patch to fill entirely with the orange liquid.

Let's talk about sweat: We tracked hydration with the Gatorade Gx smart patch

Once your workout is finished, you use your phone's camera to scan the patch to feed the data into the Gatorade Gx companion app where it will be analysed to offer preparation and recovery plans.

Currently, the app is only available for iPhones, but there are plans to launch an Android version too.

It's also currently only accessible in the US.

There are two ways to make use of the GX platform. You can plan fitness targets and the app will concentrate on three things to generate a Gx score, which indicate your progress toward that goal.

Those three metrics are training load based, which is based on duration and intensity of workout. That's also joined by recovery based on sleep and lastly there's nutrition, which is tied to ticking off recommendations made in the app on what to consume during the day.

Let's talk about sweat: We tracked hydration with the Gatorade Gx smart patch

The other way is to connect to apps like Garmin Connect and Strava, which will pull in details of your tracked workouts including temperature and combine with the data from your patch.

It's also better to pull in sleep data here as well to generate the recovery data you need if you want to follow Gatorade's fitness plans.

Let's talk about sweat: We tracked hydration with the Gatorade Gx smart patch

You'll then get a fluid loss measurement in ounces showing you on a gauge if you're low risk or high risk of big fluid loss. It also measures sweat rate as an average in milligrams per hour and your sodium level. It will then tell you how much fluid loss you experienced during that activity and will then offer recommendations on recovery.

The idea is that when you do a workout of similar intensity and in similar temperature conditions, it can offer you the same recovery insights now that it knows about the kind of fluid loss you experienced in a similar session. So it will tell you when and how to hydrate, offer nutrition suggestions and recovery guidance.

Putting it to the sweat test

Let's talk about sweat: We tracked hydration with the Gatorade Gx smart patch

The first thing to say here is that we while we could comfortably put the patches to the indoor sweat test, we had to wait for more favourable hot weather conditions to put it to the test outdoors. When the sun did turn out though, it's a relatively straightforward to wearable to set up and use.

Once you've wiped down the part of your arm where the patch is positioned and let the area drive you can quickly get the patch in place. It never fell off at any time on runs and indoor rides and workouts. Generally at around the 20 minute mark, that orange and purple dye started to appear and on hour plus runs, it usually filled up less than half of the patch.

The scanning part of the process was relatively faultless for us, and then it's over to the app to pore over the data.

You'll initially be prompted to say how hard the workout felt, how much fluid your drank during the session and then provide your numbers on sweat rate, fluid loss and sodium level along with building your recovery plan.

For workouts where you haven't used the patch, you have the option to provide weigh in/out information, which is an alternative way to measure those losses.

Let's talk about sweat: We tracked hydration with the Gatorade Gx smart patch

So for a sweaty 45 minute HIIT indoor ride, it reported a sweat rate of 309 milligrams average per hour with a low sodium loss.

With 8 ounces of fluid intake, it reported 7 ounces of fluid loss and 0 sodium loss.

It suggested hydrating as normal for the rest of the day, consuming 20g of protein before the early afternoon and doing some active recovery like foam rolling or stretching with links to sources to better understanding the nature of that active recovery.

It also looks to what you should do with regards to sleep and helping your body to recover. It suggested consuming casein (a protein) 10-30 minutes before bedtime and sleeping no later than 1.30am to aid optimal recovery.

If you do have a sleep tracker to pair to the app, that can help to better inform those sleep recovery decisions too.

Is this the future of hydration tracking wearables?

Let's talk about sweat: We tracked hydration with the Gatorade Gx smart patch

The Gatorade GX Sweat Patch definitely feels like a first generation product and there's some things we liked and things that needs some refining. We liked the fact the form factor of the patch made it easy to wear and didn't feel intrusive either.

Though it's clear that there's other areas on the body that it would be better positioned to gather sweat from a workout like the chest or back. Trying to scan something on your sweaty chest or back is clearly more challenging than doing the same on your arm, so it's clear a compromise has been made here.

We also liked the fact that you can connect other apps here like Apple Health, Garmin Connect and Strava, which actually makes the platform much nicer to use and removes some of the steps to logging a session where you've used the patch to track your sweat.

The recommendations in general didn't seem to vary that greatly for us for runs and indoor rides though. Our workouts usually lasted around the 45 minute to just over an hour mark, and it tended to offer similar protein consumption suggestions, though it was nice to see that generic foods like scrambled eggs or yoghurt are recommended as opposed to a plug for specific branded products.

There is unsurprisingly some of that here too, but Gatorade certainly doesn't go over the top with it as we'd expected it to.

Let's talk about sweat: We tracked hydration with the Gatorade Gx smart patch

The Gx score and fitness plans aspect of the platform feels like it still needs a bit of work. While everything is cleanly presented in the app it does feel like elements need to feel more connected.

Gatorade wants to create a holistic approach here that puts sweat tracking at the heart, but Phanke as tells us, it wants to make it easier for the athlete by providing them with more recommendations and information to make their whole approach to sports nutrition better.

It needs to make sure it strikes a good balance about what it tracks and records with how it presents it as there's a fear it could get too complicated for its own good.

A lot of the value though comes down to whether those sweat rates and sodium loss readings are accurate and reliable. Both Epicore Biosystems and Gatorade have put serious testing time into the patch with findings and studies having been published in scientific journals as far back as 2009. There have been some interesting tests with the patch like from the folks at Precision Hydration, who found some overestimation in sweat rates based on their advanced sweat tests. It also suggested the patch offered good estimates of sweat and sodium concentration.

Let's talk about sweat: We tracked hydration with the Gatorade Gx smart patch

Wareable verdict

What the Gatorade GX Sweat Patch feels like right now is offering a good form of guidance that has been previously been available to serious athletes who have the money and access to lab-based tests to get the hydration insights that can make the difference.

$25 for two patches that are single-use certainly isn't cheap and with a time limit on how long the patches are designed to track sweat and sodium loss, it's not something the average marathon runner or ultra runner could make good use to strategise hydration plans.

That's because validation of the patch has been designed for the 20 minute to 2 hour period Gatorade recommends.

You could use a few patches to create profiles for types of activities you regularly use so that you can have a better sense of how to prepare and recover and the guidance for us felt useful without needing more patches. You'd of course need to make sure the conditions are roughly the same to make sure the available recommendations on hydration and recovery are useful.

In its next iteration, it would be nice to see it become cheaper or even offer real-time feedback or integration with watches to make this innovative sweat patch a really valuable tool to have in your training armoury.

How we test

Michael Sawh


Michael Sawh has been covering the wearable tech industry since the very first Fitbit landed back in 2011. Previously the resident wearable tech expert at Trusted Reviews, he also marshaled the features section of T3.com.

He also regularly contributed to T3 magazine when they needed someone to talk about fitness trackers, running watches, headphones, tablets, and phones.

Michael writes for GQ, Wired, Coach Mag, Metro, MSN, BBC Focus, Stuff, TechRadar and has made several appearances on the BBC Travel Show to talk all things tech. 

Michael is a lover of all things sports and fitness-tech related, clocking up over 15 marathons and has put in serious hours in the pool all in the name of testing every fitness wearable going. Expect to see him with a minimum of two wearables at any given time.

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