Staying properly hydrated is a challenge for any runner but it is a particular challenge for athletes running in the heat and humidity of a southeastern summer. Beyond making sure one consumes enough water, runners have to contend with their electrolyte intake. Compound this problem with longer efforts and the issue only gets more confusing.

The Nix Biosensor attaches to a one-time use adhesive patch that stick to the athletes arm.

Should you drink just plain water? Or something like a Nuun? Or maybe you need something with a much greater concentration of electrolytes, like an LMNT? Is that too much, though? Are you sweating out enough electrolytes for that? Have you had too many electrolytes??

Unlike other training advice that often follows basic rules, electrolyte loss is very unique to each individual. For example, sodium loss in sweat can be drastically different from person to person, from as little as 200mg of sodium per liter of sweat to as much as 2,000+mg/l! (Have you ever been drenched with sweat and covered in salt stains after a run while your friend looks like they barely sweated a drop?) This means, what works for your friend could be horrible for you, and often with real consequences like loss of performance, migraines, cramps, and even kidney damage.

That is where the Nix Biosensor comes in.

In the past, the only way for athletes to figure out approximately how much electrolyte loss they were experiencing was through an expensive sweat test at in person testing center; something that is just not practical for most people. Thankfully, a new product has recently hit the market aimed at empowering athletes to monitor their hydration and electrolyte loss easily and in real time.

The Nix Biosensor.

How it works:

The Nix Biosensor is comprised of two parts: the main sensor or “pod” and an adhesive patch that it connects to. The athlete simply attaches the adhesive patch onto their arm and locks the Nix pod onto the patch. The pod pairs with the Nix app where you can start a workout. While you are working out, the patch absorbs your sweat and the sensor in the pod interprets the information sending it to the app. While you are using the sensor during a workout, the app will give you alerts when you have lost a certain amount of fluid and indicate an approximation of how much electrolyte loss is occurring. When you have completed your workout, the app, utilizing the data from the sensor, will give you a snap shot of your fluid and electrolyte loss so that you can more accurately rehydrate.

Pros of the Nix Biosensor

The Nix Biosensor meaningfully fills in a piece for the puzzle for many athletes, namely, “approximately how much fluid and electrolyte loss do I regularly experience during a workout.” This is incredibly helpful information especially for someone who sweats a lot or who regularly runs into issues related to hydration and performance. The more you use the Nix Biosensor — especially through a variety of situations and climes — the more the hydration picture gets filled in for you as an individual. The Nix Biosensor is a particularly valuable tool for ultra athletes or anyone prone to particularly long efforts. The sensor or “pod” is small enough that it isn’t too intrusive (it weighs less than a half an ounce), the patches are latex-free, and the app is easy enough to navigate. It also pairs with Garmin and Apple Watches, so you can get your hydration alerts on your wrist in real time; integrations with Strava, Swift and Wahoo will be coming soon. The Nix comes in a protective case so it can be easily thrown into a gym bag without fear of damage and it charges quickly and the battery lasts up to 36 hours. Retailing at $129, it is significantly cheaper than scheduling a sweat test, and of course, more dynamic and easier than traveling for a one time test.

Cons of the Nix Biosensor

An example of a Nix sweat profile after a workout

The biggest con of the Nix Biosensor is the fact that the sweat patches are not reusable. For each workout you use the sensor for, you need a fresh patch. This is understandable as the patch is what is absorbing the sweat from that workout, but it does make you think twice before just throwing on the Nix. The biosensor comes with 4 patches when you purchase it and refills come in packs of 4 at $25 a pack. This means that each sensor pre-tax is a little over $6. Not going to break the bank but also plenty enough that you aren’t going to be using the Nix for every workout. It also means waste is being generated — at this time it is not clear if there is a way to recycle the patch which does have plastic on it for the pod to lock onto. Speaking of not using the Nix for every workout, it is not recommended that athletes use the Nix sensor for workouts less than 45 minutes long. Because the patches aren’t reusable, most people would be saving the Nix for longer efforts anyway, but it is still something to note. Another con of the sensor is that it is not going to provide a break down of which types of electrolytes you lost in what quantity; did you lose a lot of sodium and not much magnesium? Vice versa? The Nix only offers aggregate data on the amount of electrolyte loss an athlete experiences. The reality is most people wouldn’t do anything with that information anyways — the electrolyte supplements have the ratio of electrolytes in them that they have regardless of what you lost — but it would be extra cool to be able to see that information parsed out. Lastly, even though $129 is very reasonable for a training device, it is still not a cost that will be accessible for everyone.

Who should buy the Nix Biosensor?

Ultra athletes, those training for races (especially those wanting to PR or qualify for certain events) people prone to working out in the heat, those who experience cramping or migraines after training or races, those who sweat a lot… At the end of the day, the Nix Biosensor is helpful for anyone who is interesting in dialing in their hydration. Especially as we come up on summer in East Tennessee, I am personally looking forward to getting more data through Nix to understand myself and my training needs more.

Interested in getting the Nix for yourself? Pick up a training bundle and your refill patches online and in store at Terra Running Company today!

As runners we know that it important to stay hydrated and replenish our electrolytes. We know that we lose water and electrolytes through sweat and that the longer we go (and the hotter that it is) the more we will lose.

But what exactly are electrolytes?

Electrolytes are essential minerals that our bodies need to properly function. Some of the most common include: sodium, calcium, potassium, chloride, phosphate, and magnesium. These minerals carry either a positive or negative charge when dissolved in water (humans are made up of 60% water!); they help our cells regulate chemical reactions, maintain fluid level balance, and transmit electricity throughout our body. They aid our muscles, nervous system and heart especially, since these rely heavily on electrical impulses to function; in truth, they are used by every cell in our body.

In other words, electrolytes are a big deal.

Imbalances can be serious and need to be treated by a medical professional. Thankfully, most people shouldn’t end up at that level of imbalance (barring some kind of medical condition) however, athletes especially might end up sidelined by headaches, nausea and general malaise when not correctly hydrating and replenishing their electrolytes. Since electrolytes are found in the water in our bodies, when we sweat, we lose those electrolytes along with the water. This excessive sweating (and/or vomiting or urination) depletes our bodies of both the water and electrolytes needed to maintain homeostasis.

To stave off heat related illness the CDC recommends drinking 8oz of water ever 15-20 min not consuming more than 48 oz per hour (the risk of electrolyte imbalance goes the other way as well!). For someone running this is not super realistic, which is why it is important to hydrate well both before and after a run. On a hot day, a runner can sweat out 58-64 oz per hour (yikes!); since you should not be drinking more than 48 oz a hour, this means you will undoubtedly be finishing your run dehydrated and will need to rehydrate over the course of a few hours.

To prevent the effects of dehydration and electrolyte imbalance, make sure to replenish fluids regularly and when sweating excessively to consume balanced electrolyte enhanced drinks like Nuun, Skratch, etc. It is worth noting that not all all sports drinks are created equal. As an example: Gatorade contains 160 mg of sodium and 50 mg potassium but it does not contain other electrolytes like magnesium, calcium, or chloride. Contrast this with Nuun Sport which has almost double the sodium at 300 mg, triple the amount of potassium at 150 mg, as well as magnesium, calcium and chloride. Sports drinks like Gatorade are also very high in sugar, which is not necessarily a bad thing for an athlete that needs easily digestible carbs, but it is not always the best option for someone simply needing to replenish electrolytes from a shorter activity or from a hot day. If you are needing a higher calorie option than Nuun (which only clocks in at 15 cals) for longer activities but don’t want the excessive amount of sugar found in Gatorade, check out Skratch which is made from fruit and has more carbs than Nuun (18 grams of sugar vs 1 gram) and an electrolyte profile that matches what is lost in sweat.

Whatever you are drinking to replace your electrolytes, Terra is here to help!