Why hydration monitoring wearables are going to be a big deal

At Wareable we're always looking ahead to the next generation of fitness trackers, smartwatches and VR headsets.

Fitness trackers continue to be at the forefront of much of the innovation that's happening at the moment, whether that's to help us keep a check on our stress levels or even to tap into our emotional state to see if we're really in the mood to go out for a run.

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The concept of monitoring hydration could well be one of the next big additions. In a recent survey, hydration tracking featured high on a wish list for next-gen wearables.

Here's a breakdown of where we're at with hydration monitoring wearables, what they are capable of, and when we can expect to see them.

Why hydration monitoring is a big deal

What exactly do we mean by hydration? In really simple terms it's all to do with replacing the water in the body. The most obvious way to top up on water is to drink it, but you can also eat foods with high water content and drink other fluids that can prevent you from getting dehydrated – when that loss of body fluids outweighs how much you're putting back in.

You need that water intake to ensure your body is in full working order and in good health, because it'll help with things like like maintaining your temperature and removing waste from the body. It's also a big deal for heart health, particularly for sport, as it helps the heart more easily pump blood through the blood vessels to the muscles.

But there's a bit more to it. We recently spoke to Dustin Freckleton, founder and CEO of BSX Athletics, a startup that has developed LVL, a wrist worn wearable that can monitor hydration as well as track fitness, heart rate and sleep quality. Freckleton, who suffered a stroke due to dehydration, summed up the value of closely monitoring hydration.

"Hydration matters for anyone that sweats and that's everybody," he explained. "Our bodies are primarily water. Everything from exercise to better sleep, to weight management, to better mood. All of that comes back to hydration. Hydration is one of the most primal instincts we have as human beings. You can go a lot longer without food than you can without fluid."

Measuring hydration

Outside of promising developments in wearables, methods such as urine analysis or measuring body mass before or after exercise are among the most common methods used to track hydration, particularly when exercise or fitness is involved.

It's by no means a straightforward metric to measure, as Azar Alizadeh, a senior material scientist at GE Global Research, explained to us. Alizadeh is working on several projects focused on developing wearable hydration devices, including one project in collaboration with the United States Air Force to develop sensors that monitor performance of its special operations units.

"It has a lot to do with the fact that hydration is a very complex phenomenon," she told us. "A lot of us have very complex compositional mechanisms that allows us to tolerate a lot, like having to fast for an entire day for example. Outside of that, you need to consider aspects like diet, age and the ability to acclimatise to an environment. It makes it a very difficult phenomenon. There are a lot of commercial claims about hydration but none of them are actually measuring the hydration with the complexity that it deserves."

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In the case of LVL, it uses optical light-based technology, specifically red light based sensors as opposed to the green ones used by the likes of Fitbit, Apple, Garmin and Apple. By opting for red light it is able to recognise the water signals at various depths of the body to measure the hydration.

Halo Wearables is another company that has developed a wrist-worn wearable which promises to measure hydration levels and also uses optical sensors to do this. Additionally, it features electromagnetic pads that emit electric impulses at intervals. The set up is able to then monitor sodium and potassium levels in a user's blood plasma.

Penn University startup GraphWear Technologies has developed a wearable sensor patch that is placed on the lower back, said to be the sweatiest place on the body. It then links to a companion smartphone app that can monitor glucose and electrolyte levels in real time. The idea is that by analysing a player's sweat, it can help determine when to top up on fluids.

Measuring from the wrist

Where to place sensors to ensure readings are accurate and reliable has been a major topic of debate, especially with regards to wrist-based heart rate monitors like the Fitbit Charge 2 and the Apple Watch Series 2. Both the LVL and Halo Edge are worn around the wrist, and there's a debate whether this is the best place. BSX's Freckleton openly admits that is the case.

"The wrist is not the best place to measure from a science perspective," he told us. "So that causes our scientists headaches. From a product perspective, it's geographically the most valuable estate on the body."

GE Global Research scientist Azar Alizadeh has similar concerns about where these hydration readings should be taken from.

"People have started to look at this concept of total body sweat," Alizadeh explained. "Imagine you're conducting a study where someone is working out on an exercise bike and you're collecting every drop of sweat that came from the subject. You could check on the sweat coming from the lower back, upper chest, upper arm and leg. The measurement is going to differ depending on the type of exercise you are doing. You might use your leg muscles more and therefore produce more sweat from different locations, and it's going to be different from the overall sweat rate. The concentration of electrolytes are all very different."

When will we see a hydration monitoring Fitbit or Garmin?

That's the big question. While the Halo Edge is already available to order and LVL looks on schedule to launch next year after raising big bucks via Kickstarter, there's been no indication as yet that this is something the big players are thinking about building into their devices. But that doesn't mean it's not on the cards.

Fitbit, like most fitness tracking platforms, doesn't entirely ignore the importance of monitoring hydration and does let you manually log water intake. It also offers support for smart water bottle setups like the Thermos hydration bottle and Trago smart lid (which also works with the Apple Watch), to keep a closer eye on fluid intake.

So don't be surprised if the likes of BSX Athletics and Halo Wearables are joined by some more high profile names in the not-too-distant future.