In a world the place unmanned spacecraft have landed on Mars and artificial intelligence can learn your thoughts, one would assume somebody would have found out a exact approach to measure how a lot athletes ought to drink whereas exercising. Hydrating, or changing physique fluids misplaced by way of sweating, exhaling, and eliminating waste, is important. When 2 or extra p.c of physique mass is misplaced by way of dehydration, the physique can go haywire, with elevated cardiovascular pressure, lowered cardio train efficiency, and impaired thermoregulatory perform. After shedding 12 p.c of physique mass to dehydration, a human will die.

It’s uncommon for an athlete to train to the purpose of dying by dehydration. But it’s additionally odd to contemplate that, for such an essential physiological necessity, many athletes depend on thirst as their definitive information to how a lot they need to hydrate throughout train. The hassle with that in-built system is twofold. By the time your mind registers that you just want water, your physique is usually already dehydrated. Also, it’s simple to alleviate your thirst earlier than you’ve utterly rehydrated.

Outside a lab, probably the most correct commonplace for figuring out an athlete’s fluid loss is to weigh the nude physique earlier than and after the exercise. (For each pound of physique mass misplaced, 16 ounces of water ought to be consumed.) But that technique doesn’t assist a runner decide how a lot fluid they’ve misplaced whereas on mile 16 of a marathon.

Cyclists can depend on a GPS computer with a drink alarm that flashes a reminder to take a swig from a water bottle each quarter-hour. Runners and health club rats can put on a smartwatch with a hydration sensor, just like the Apple Watch, which makes use of electrodes positioned towards the pores and skin to measure electrical conductance of the wearer’s sweat. This can decide the focus of electrolytes (or lack thereof) within the sweat, which helps decide the person’s hydration degree. There’s additionally a $25 gadget referred to as the GX Sweat Patch, marketed by Gatorade, a one-time-use biosensor that, when utilized to the interior left forearm, measures the person’s sweat fee, fluid loss, and sodium loss. When that information is transferred to the companion app—which runs on iOS or Android—it operates as a suggestion for the athlete’s future efficiency.

Until not too long ago, nonetheless, biosensing know-how that may analyze the content material of an athlete’s sweat to offer personalised, real-time hydration suggestions as they’re exercising has been out of attain as a result of the sensing tech hasn’t been inexpensive sufficient to construct right into a shopper product.

In December, a Boston startup based by Harvard Business School graduate and marathoner Meridith Cass unveiled the Nix Hydration Biosensor, the primary wearable sensor that guarantees to offer real-time sweat science to athletes. Cass, who can be a former collegiate basketball participant, began fascinated with biosensing know-how to measure hydration after she struggled together with her personal physique’s response to warmth and humidity when coaching for marathons. “I was feeling very sluggish on some of those longer runs,” she says, “and I wondered, ‘could a hydration sensor be a thing? And would anybody find it useful other than me?’”

Nix works like this: When hooked up to the bicep (through a protecting movie on the underside of the patch, which is concerning the dimension of a spherical orange slice), the patch measures the sweat profile of the physique domestically, extrapolating it to the total space of the physique through algorithmic computation. As sweat dribbles throughout the electrodes on the bicep patch, the patch measures the content material of the sweat twice alongside its circulation path. By evaluating information on these two areas, the sensor can inform how rapidly fluid is shifting by way of the physique. When related through Bluetooth to the Nix app, the sensor relays hydration notifications to the cellphone in intervals personalized by the person. The level is to maintain the athlete, as they’re figuring out, inside 1 p.c of their beginning physique mass (or 1 p.c of dehydration) to keep away from the nasty pitfalls that include dehydration.