I frequently use a sports watch linked with an external heart rate monitor when I work out. Despite the improvements that have been made, wrist-based heart rate monitors cannot compete with those that are worn around the chest or on the arm when it comes to accuracy. This is especially true for activities that are performed at an emotional level.

Frontier X sparked my interest for precisely this reason. It promises physiological metrics that are significantly more comprehensive than those provided by a standard heart rate chest strap. This covers things like your breathing rate, step cadence, training load, body shock, and the variability of your heart rate (HRV).

However, the sophisticated heart information that this gadget provides, including the electrocardiogram (ECG), cardiac rhythm, and cardiac strain, is what truly sets it apart from the competition. If you exceed the parameters that have been set, you will be notified in real time by vibration. Because of this, you can exercise without worry because you are aware that the activities you are performing are not putting an unnecessary strain on your heart.

All of this information can be very helpful, particularly if you are currently dealing with pre-existing problems, are recuperating from surgery, or are experiencing COVID. That implies the Frontier X is a wearable that falls somewhere in the middle of a health and sports category.

The wearable was initially produced by Fourth Frontier and has been available on the market since the late year 2020. According to the firm that makes it, it is a "chest-worn gadget that is used for athletic training, cardiac rehabilitation, and remote monitoring — meant to keep you healthy and away from the hospital," according to the firm that makes it. And I'd say that's a fairly spot-on description of it.

Fourth Frontier is an ambitious company with locations in the United States, the United Kingdom, and India. To expand its business in July 2021, it could secure approximately $10.5 million in funding. At the moment, you may purchase a Frontier X in the United States of America, Canada, Europe, and India. On the Fourth Frontier website, you may buy it for the standard price of $499. You have until the 14th of February to take advantage of Valentine's Day promotion that gives you a $100 savings. This kind of campaign is run by the company every once in a while.

The device makes a lot of claims, but does it live up to them? Read on to find out what I think of it after putting it to use for a few weeks.

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Frontier X review: Design & hardware

  • It has the appearance and the feel of a heart rate chest strap.
  • A simple LCD monitor and a group of indication LEDs can be found on the core unit.
  • Compatible with smartphone apps, stand-alone use, and devices made by third parties
  • Battery life of two weeks under normal conditions

Look & feel

Non-traditional thinking The Frontier X comes with the pod that houses the brains of the unit, two elastic chest straps (one black and one red), a Micro USB cable for charging, and two protective inserts made of black plastic, and a quick start guide.

This whole package comes with a good warranty for one year and a risk-free trial that lasts for thirty days. The second option is helpful if you are unsure about making the buy, as it enables you to test out the product without incurring any costs.

It is also important to point out that the cost of the package already includes a complimentary assessment of your training statistics by a Cardiac Exercise Specialist who works with you one-on-one. This is not a checkup of any kind; rather, it is done to identify possible problems.

The device is quite reminiscent of a conventional chest strap for measuring heart rate. Putting it on is exactly the same. You can secure it to your body with any of the two provided bands. Because of the mechanism, you can adjust how tightly the hold is held or how loosely it is held.

It is a little finicky and requires some getting used to, but that may be because I am more accustomed to working out with heart rate armbands than chest straps. In the beginning, when I wasn't quite sure what to do, I discovered that I was growing increasingly frustrated. It would be best if you made sure that the band is snug around your chest for it to provide you with reliable readings. But we'll talk more about that in a bit.

It is necessary to press forcefully for the core unit to slot into place after being snapped onto the strap. There ought to be a click that you hear. Before you begin, you need to make sure that the two protective inserts made of black plastic that is located inside the metallic electrode socket have been removed. It is recommended that the device be positioned to be located exactly in the center of the person's chest.

There is no possibility that the strap will come off because the hold it provides is exceedingly secure. In addition to that, the construction is rock-solid. Even if you were to drop the device by accident, I do not believe it would sustain significant damage (which I did once or twice).

Everything around your chest has a light and airy sensation. The actual dimensions of the core unit are 73 millimeters by 24 millimeters by 13 millimeters, and it weighs 25 grams. That's quite similar to a regular chest strap for measuring heart rate.

In terms of its water resistance, the gadget has been given an IP67 rating, indicating that it can survive being immersed at depths of up to 1.5 meters. That clears the way for people to start swimming in the pool.

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In addition to the indicator LEDs, there is a display located on-board

There is a screen located on the front of the core unit, but I did not find it to be very useful. Although it is a good tool to have, it does feel a little bit unnecessary at the same time. This is because if you do not have a mirror in front of you, there is a slim likelihood that you will be able to use the information effectively. Reading something that is sitting across your chest is not an easy task, so give it a shot.

Having said that, it is beneficial to know what mode the device is in, how much battery life is remaining, and other such information. When you have finished your workout and removed the pod from its strap, it will also provide you with an activity summary that you may read.

The underside of the Frontier X gadget houses the device's solitary physical button, which is used to control various aspects of the device. This will also help indicate to you whether or not you have put it on the correct way around. When the strap is fastened to your chest, the red button should be oriented such that it faces downward toward the earth.

The device can be turned on with a single click of a button. A single action can be started and stopped with just two presses. In addition, you can use the button to log event markers while you are exercising.

A narrow band of LEDs can be found at the opposite end. They radiate light in one of the following three colors: blue, green, or red. This is used as an indicator that the device is paired, turned on, and ready to pair, that it is switching on and off, and several other states. The controls are, in all honesty, not too complicated and get right to the point.


During your workout, you can utilize Frontier X in one of three different ways. By default, you start and stop exercises on your smartphone by pairing it with the appropriate app for either iOS or Android and using that interface. Because the gadget relies on Bluetooth to communicate with its environment, ANT+ is not supported in any capacity. You also can use Frontier X on its own and then sync everything to the smartphone subsequently.

The final possibility is to use it in conjunction with devices made by a third party to obtain an external heart rate reading. The following brands are included in this category: Garmin, Polar, Wahoo, Zwift, and Peloton. The linked device receives heart rate data from the Frontier X when it is set to this mode.

I usually wear a Garmin Forerunner 945 watch when I work out, and I had absolutely no trouble pairing it with Frontier X. The connection was established in a flash, and there were rarely any interruptions at all while I was working out.

A recent upgrade to the firmware gives you the ability to link Frontier X to various devices. In addition to the smartphone, a maximum of two other devices from a third party are permitted to be used simultaneously. It is highly improbable that you will require that many, but having them available is always a good idea.

You'll discover that Fourth Frontier is fairly adept at producing regular firmware upgrades for its products. During the most recent half-year, there has been, on average, one new update every month. In addition to the routine correction of bugs, each brought with it several enhancements and new functionalities.

Battery Capacity

If you use the Frontier X nonstop when the battery is fully charged, you may anticipate that it will last for around one day, which might not seem like a significant amount at first. However, it is quite likely that most people will use it on occasion, most frequently as a chest strap while working out. Considering all of this, the average user will only have to look for a charging source once every two weeks.

After using Frontier X for a couple of weeks, I could have gone the entire time without needing to charge the device. I performed a speedy top-up every four to five days to be on the safe side. Because the cable that is used to refuel is a regular Micro USB, there will be no issue if you need to replace it if you misplace it.

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The Functionality of the Frontier X

  • Captures data on the user's heart health even while they are exercising.
  • You get additional insights while still having the ability to utilize it as a standard heart rate chest strap.
  • Physiological data is broken down into the details and shown on a mobile app and website dashboard.
  • Continuous ECG recording over the entire day and night

Setup & usage

The initial set-up consists of rather routine activities. Install the Frontier X app on your smartphone, set up an account, respond to a few fundamental questions, and then pair the device. When you first set up an account on your mobile device, you'll find that the same username and password will get you access to the web dashboard on all of your devices, including your computer. This provides access to more information than the mobile app, making it a handy resource for looking things up.

Instead of using a third-party device to keep track of my workouts initially, I used the smartphone app that came with my Frontier X watch the first few times. You can accomplish this by fastening the strap to your chest and activating the device by pressing the physical button. The display will come to life and show you the current time, followed by a breakdown of your most recent workout and the percentage of charge remaining in both the battery and the memory.

Through trial and error, I discovered that it is ideal to moisten both the sensors on the strap and the areas of your skin with which the strap comes into contact. Otherwise, there is a possibility that there will be voids in the data when you first begin your workouts. There is nothing unusual about this; the sensors on most heart rate chest straps function more accurately after being wet.

Then, you will need to do the following: 

  • Open the smartphone app, navigate to the Activity tab, and select the type of activity (run, cycle, walk, strength, etc.).
  • You currently have the ability to edit notifications, which can be found here. The cardiac strain index is measured by one of these, and the breathing rate is measured by the other.
  •  You can set the maximum and minimum values for both of these. Whenever the threshold is crossed while you are working out, you will hear a double buzz to let you know.
  • Save, then click the start button. The initial readings arrive approximately twenty seconds after the transmission has begun

More on alerts

The fourth Frontier focuses a particular emphasis on one's rate of breathing. The organization thinks that this metric is equally crucial for monitoring your heart rate during physical activity. Even though this can be up for discussion, most people would agree on the significance of cardiac information. Furthermore, here is where Cardiac Strain comes into play.

ST depression is the term used while talking about cardiac strain in the medical field. According to Fourth Frontier, its patented metric "measures the amount of oxygen deprivation that is experienced by the heart muscles."

When you have a high degree of cardiac strain for an extended period of time, it might cause damage to the cells in your heart. In general, you should avoid training on such a frequent and intense basis. This is because engaging in such behavior might, over the course of time, lead to illnesses such as fibrosis or arrhythmias. Because of this, Frontier X can be quite helpful because it will vibrate and provide you with an immediate warning if you enter a hazardous zone.

By analyzing your electrocardiogram (ECG), the Cardiac Rhythm function can also identify any abnormalities in your heart's regular rhythm. After the workout, the statistics will provide you with a pie chart that shows the percentage of time spent in each of the three zones: blue (normal sinus rhythm), yellow (another rhythm), and gray (Not interpretable).

The charts, which divide the data into 20-second intervals, contain more information about cardiac rhythm if you look closely. That 20-second session will be highlighted for further investigation if there is a change in Cardiac Rhythm that appears suspicious.

I was relieved to find out that the majority of my workouts fell within the green and yellow zones, which indicate that my heart is not being overly stressed. My values for cardiac rhythm were also virtually totally within the normal range the entire time. Having had two close calls with COVID-19, the most recent of which was around two months ago, knowing that my heart measurements are within the healthy range when I exercise provides me with a sense of relief.

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Real-time summary while you're working out, along with detailed stats post-workout

Physiological data can be viewed in real time on the mobile app on your smartphone while you are working out. Running and walking were the primary activities in which I engaged while using Frontier X. Effort, Strain, Heart Rate, Heart Rate Variability, Training Load, Cadence, Distance, and Pace are some of the metrics that may be measured for these kinds of activities.

A simple touch of the device's physical button allows you to record noteworthy events while you are working out. For instance, if you were feeling a specific strain, having difficulty breathing, or even just beginning a new lap, you may consider taking a break. You will be able to view this information later on in the exercise summary charts; it will be presented to you in vertical black lines to draw your attention to these occurrences.

You can leave your phone behind while you exercise if you don't want to be able to monitor your progress in real time. Pressing the button on the device itself is all that is required to begin and conclude the session. Everything will be saved to the memory that is already on board.

After your workout, you should let the Frontier X sync with the app on your smartphone. Depending on the intensity of your workout, this step often takes two to three minutes. After that, dig into the plethora of data, including stats and graphs, provided on various workout elements. There is also a GPS map of your path that is displayed when tracking via a smartphone.

These statistics are rather typical; they are essentially the same as what you would obtain from wearing a heart rate chest strap. Others, such as a trace of an electrocardiogram (ECG), cardiac strain, cardiac rhythm, and body shock, are quite singular.

Sorting through all of this information can easily consume a significant amount of time. It is not typical of what you would get with other gadgets. Thus reading it is intriguing due to this difference.

In addition to information regarding the heart's health, I believe that Body Shock also merits special mention. This statistic determines the amount of force that the body experiences as it hits the ground. It will let you know if the way you exercise is likely to cause injury to your knees or other joints. This is charted incrementally while you work out to evaluate whether there is a decline in your technique as your workout goes on.

The mobile app for your smartphone gives you the ability to view detailed charts that encompass most physiological data. You can navigate between tables, and there is even a view that allows you to compare the side of the table by the side. You also have the ability to review any alerts that may have been sent to you while you were working out.

On the other hand, the workout recaps made me an engaging reading experience. In plain English, you will be provided with an evaluation of your workout along with suggestions for how to improve for the next session. This is determined by your weekly workout Training Load, which is automatically computed on your behalf by the system.

Utilizing the control panel of the website

Reviewing your statistics is possible via the website dashboard and the mobile application on your smartphone. In all honesty, I made better use of the website's dashboard. Frontier X provides a multitude of statistics, and the structure of the wide screen makes it easy to sort through and analyze each one in more depth.

You will obtain everything that is available in the mobile app for your smartphone. Still, you will also have the option to zoom in, activate the caliper tool, and obtain additional functionality.

You will better understand all of this by looking at the following screenshots presented below. This contains a component that tracks your progress over the course of time and displays it in a graph. This portion won't make much sense initially, but after a week or two of training, patterns will start to emerge that make sense.

Combining Frontier X with a gadget from a third party

As was previously indicated, you can also utilize Frontier X with a device that belongs to a third party. I had no problems whatsoever connecting my Garmin Forerunner 945 to it as a pairing device. Connecting it is as simple as connecting any other external chest strap for measuring heart rate.

The important thing to remember is that the data is only being sent to the Garmin watch while using the Frontier X. It is not receiving any data back, including GPS data, and hence cannot function properly.

To begin monitoring a run, the first step is to initiate the activity by pressing the button on the strap twice. This will start the activity. The physiological measures should start flowing in after approximately 20 seconds of waiting. Then begin recording your activities on your Garmin watch as you normally would in the manner in which you are accustomed to doing so. After completing the task, you'll need to stop the activity on both your Garmin watch and Frontier X.

Those who own an Apple Watch will be pleased to learn that a Frontier X app enables them to select the type of activity they wish to perform and begin or terminate it directly from the watch. Additionally, it will display numerous Frontier X metrics on the watch in real-time, which is a really helpful feature. The capacity to view other physiological parameters in real-time, in addition to heart rate, is not yet accessible on Garmin watches or other watches, and it is high on my wish list.

Accuracy concerning the sample rate

In Frontier X, the electrocardiogram (ECG) signal is collected at intervals of 125 Hz, which is equivalent to once every eight milliseconds. That is a really encouraging sign. This is the measurement used to determine your heart's overall health.

When attached to a watch made by a third party, such as a Garmin, the heart rate and heart rate variability signal is only recorded once per second or two. Once every 20 seconds, if you're tracking activities from the Frontier X app. It's a mystery to me why things work this way; maybe it's to extend the battery's life.

To evaluate the precision of the Frontier X, I tested it alongside a Polar OH1 chest strap and a Garmin watch. The statistics were spot on; there was hardly any difference at all. However, I did notice that although the maximum heart rate was often the same or slightly off by one beat per minute, the average heart rate on Frontier X would typically be two to three beats per minute lower than on Polar OH1. This takes place during a 5k run. My best assumption is that it's because of the 20-second wait at the beginning and the somewhat reduced sampling rate compared to a conventional heart rate chest strap. However, this is just speculation.

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Continuous ECG recording over the entire day and night

In addition to keeping track of workouts, the Frontier X may also be used as an ECG recorder. The special mode can be activated through the app on the user's smartphone. This marks the point at which the device becomes a health wearable exclusively.

The Frontier X electrocardiogram only has one lead. However, it is more analogous to the results obtained from the V5 lead of a medical 12-lead electrocardiogram study.

In trials that compared the Frontier X to a Holter Device and a 12-Lead ECG, the Frontier X detected all of the abnormal cardiac rhythm changes (arrhythmias) that were observed by the Holter Device and the 12-Lead ECG, and it assessed heart rate and QTc alterations accurately.

There is no way for me to verify whether or not the ECG recordings are accurate in reality. But I have a few tools in my arsenal that can record an electrocardiogram, and the waveforms are fairly comparable.

The Frontier X comes with a feature that allows users to send remote readings, making it possible for them to share their recordings with a loved one or a physician. You will receive a link that you can then email to the other person; if they click on the link that you send them, they will be able to view your ECG in real time. You are presented with the exact same choice when you begin a workout using the mobile app on your smartphone.

Evaluation of the Frontier X: Pros and Cons

The game Frontier X has a lot of positive aspects to it. If I were to highlight one benefit, it would be the positive effects on heart health. Cardiac Strain and Cardiac Rhythm. They bring an entirely new dimension to the activity tracking that you do.

The functionality operates correctly and notifies you if there is a problem with it. As was said earlier, I found it to be helpful because it allowed me to relax after two rounds of treatment with COVID-19. In addition to that, there is a possibility that you are not aware of the fact that you are having problems with your heart rate. This wearable device aims to alert you if this is, in fact, the situation. It also cautions you to watch your breathing rate during exercise because an increased rate for an extended period of time might be harmful to your lungs.

The ease of use, excellent battery life, the wealth of physiological stats captured (HRV, Breathing Rate, Body Shock, etc.), the simple to use of the app and web dashboard, the ability to live-stream your metrics, and the ability to take long-continuous recordings of your ECG are some of the additional benefits that I would highlight as advantages of this product (smartwatches with ECG typically record only 30-60 second segments)

When it comes to the negatives, the wearable has a high price tag, which is especially noticeable when compared to a regular chest strap. The other drawback is that the sampling frequency of heart rate is slightly lower than what you would get from a regular chest strap that was connected to a watch. In contrast to the ECG, which is recorded almost continuously, this is not the case.

It would be beneficial to examine other information on connected Garmin watches and the user's heart rate (through a ConnectIQ app or data field) during physical activity. Since Frontier X is currently transmitting information about heart rates, there is no reason why this cannot also be accomplished.

In conclusion, I truly hope that Fourth Frontier would release an armband rather than a chest band in their next product. These kinds of tools are considerably simpler to operate than others.

The folks at Fourth Frontier put together this nifty little chart for your perusal. It compares their most advanced wearable against other types of monitors, such as heart rate monitors, smartwatches with ECG, and Holter monitors for ECG. This provides a helpful summary of the differences that exist between each.

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The conclusion of our Frontier X review: Is it really worth the money

Before I started, I thought that the Frontier X review would be brief. In the end, there is only so much that can be said about a heart rate chest strap. I was surprised to learn that it was quite a lot.

This is because Frontier X is capable of doing a great deal more than any other chest band. I'd classify it somewhere between fitness and a Fitness wearable if I had to choose.

You can use it to augment the statistics and other insights that you normally obtain from your sports watch by using it to gain new insights. Is the intensity of your workout putting an unnecessary load on your cardiovascular system? Are you able to exert more force? This kind of information will be sent to you by Frontier X.

It will even assist in the prevention of injuries by measuring the shock that your body experiences with each footfall that you take. In addition to this, I will also be recording various other physiological data that I have discovered to be helpful.

The live ECG feature is the other aspect of the wearable that it offers. If you are recovering from a cardiac problem or want to check on the health of your ticker, this can be helpful. It is a good add-on that you may choose to let other people watch the readings remotely if you want to.

The Frontier X is a great accessory to go along with my Garmin watch because it has so many great features, and I truly enjoy using it. I observed that the statistics were fairly comparable to those provided by the Polar OH1 chest strap.

It is encouraging to know that I am not overdoing it when I exercise because I have a tendency to challenge myself quite a bit. Frontier X assists me in remaining within the secure zone. It provides me with a sense of calm that I lacked in the past.

The issue that needs to be answered is: is it worth the money? The wearable comes with a hefty price tag. Now, this essentially boils down to one question: what is it that you require?

If the only information you're interested in is your heart rate, a standard chest strap that measures heart rate is the best option for you. It has a lower price point and can record a higher sampling rate for the heart rate.

However, you will not get access to the several additional pieces of health information that are included with Frontier X. It is not a piece of medical equipment. Still, it is an entirely new addition to the fitness tools you already have for cardiovascular exercise.

People who are trying to exercise despite having moderate heart issues and people who are recovering from surgery or COVID may benefit from using the device. And, more generally speaking, anyone else who wants to maintain a closer watch on their own health. When it comes to your heart, especially as you become older, you can never take enough precautions to protect it.

On the Fourth Frontier website, Frontier X can be purchased for a price of $499 on average. This includes a complimentary review of your current exercise routine by a Cardiac Exercise Specialist. This is not a medical examination of your heart; rather, it is a consultation designed to make you aware of any possible problems that may require further research. This conclusion was reached after analyzing the responses provided by your exercise data. Because Fourth Frontier runs these kinds of promotions frequently, it is in your best interest to regularly check back on their website.


Veronica is a culture reporter at Collaborative Research Group, where she writes about food, fitness, weird stuff on the internet, and, well, just about anything else. She has also covered technology news and has a penchant for smartphone stories. .

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