A man working out with a fitness device
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20 fitness tracker terms to help you find the perfect workout device

Exercise your knowledge to help bump up your fitness level, and find the smartwatch or tracker for your needs

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You've taken a step in the right direction by making the commitment to exercise. What better way to monitor your progress than with the aid of a fitness tracker or smartwatch. There are dozens of solid options on the market from the Apple Watch 5, to the Polar Ignite that double as both stylish wearables and fitness tracker. But before you buy your first, or next, device, make sure you know what fitness trackers can actually measure, their features and functions, and how your device is likely to help boost your fitness levels as well.

These 20 terms cover the basics of what fitness trackers can measure, the data they collect and even details that can help you improve your own level of fitness. Understanding them will likely help you narrow which device is right for your goal, whether that's a plan to run a marathon, or just increase your physical well-being over time.

Active Energy

Your active energy, or active calories, that you spent are those that are measured while you're moving around. That can include a workout class, walking the dog, anything that keeps the body in motion. Fitness trackers are not always the most accurate at measuring calorie expenditure exactly, but they can give you a fair assessment. And keenly, expending more energy at all, even walking for five minute an hour — and burning more calories — can help maintain weight, according to a 2019 article from LibreTexts, an online education project launched through the University of California, Davis.

Anaerobic Exercise

Sometimes people perform their exercise in "bursts" so there is a small period of time using high energy followed by a rest period, and on and on until complete. This will take fuel stored in the major muscle groups to help build muscle fibers. Think of lifting weights as an example of anaerobic exercise.


Most fitness trackers are set up to work in conjunction with an application (app) on a smartphone or tablet. The fitness tracker will receive and release data to the app after setup is completed and the two devices are sufficiently synched up to communicate.


Many fitness trackers rely on Bluetooth connectivity to communicate between the tracker and a smartphone or tablet. This connection will take the information gathered from the tracker to send reports, summaries, and other data to the smartphone or tablet. Make sure your Bluetooth is enabled so this happens.


Many fitness trackers not only monitor physical movement, but calorie intake and burn as well. A calorie is a unit of energy derived from food that allows the body to perform its metabolic processes and be physical. You may wish to keep to or burn a particular number of calories per day and many fitness trackers can aid in that process.


The display is the section on your fitness tracker which will show you the data you are monitoring during exercise on a small screen. The display may also show the time of day, temperature, or be the spot where notifications and alerts are visible.


ECG is the abbreviation for electrocardiogram. This measures the electrical activity of the heart and is often the manner in which a fitness tracker measures heart rate.

Fitness Tracker

Of course, you'll need to know what the device is on the whole. A fitness tracker tracks and monitors physical activity and other physiological functions like breathing, sleep, calorie burn, and heart rate.


Many people want to measure how many steps they take per day by monitoring their steps using a fitness tracker. Gait is a person's walking style, including the speed, length of stride per step, and other leg and hip movements. A tracker can help the user make the most of every step by delivering detailed conclusions about their gait.

Heart Rate

One of many important items monitored and tracked by fitness trackers is heart rate. Put simply, the heart rate is how many beats per minute your heart takes. On average, a resting heart rate (meaning you are not being physically active) is around 72 beats/min.

Maximal Heart Rate

Maximal heart rate (MHR) is the maximum number of beats per minute your heart should take when functioning at top intensity. A fitness tracker can help you determine what this should be in order to work up to your best capacity carefully. 220 - your age is a generally accepted formula to determine your MHR.


When you wear your fitness tracker, you can set it to alert you of your progress, remind you to get up and move, or message you when you've reached your peak heart rate. These are all examples of notifications you can receive from a fitness tracker. You can set your fitness tracker to notify you of pre-determined items or use the generic ones built in to your tracker already.


People often set a goal for their exercise plan, for instance, biking for 30 minutes straight at a "level 5" on the stationery bike. However, once this becomes too easy and the body is no longer challenged by this intensity, the person will reach a plateau in their fitness program and no longer reap new results. Time to rev up the game plan.

Resting Energy

Your resting energy is the energy or calories you burn while you're not in motion. These are calories spent while sitting, for example. But they're also the calories that you spend to just keep your body and its vital organs from your heart to your lungs, working. In fact, the Harvard Medical School estimates that 60 to 75 percent of the calories we burn everyday come from resting energy. Fitness trackers typically measure your resting energy by calculating it based on static information including your age, gender, height and weight.

Resting Heart Rate

Many fitness trackers will check out your resting heart rate which is the number of beats per minute of your pulse when you are inactive or at rest. This will provide a barometer as to how high your heart rate should get during high-impact exercise.

Running Pace

Your running pace is basically a measurement of a distance covered over time, typically measured by mile or kilometer. Nearly all fitness devices are pretty capable of measuring this, as it's just a matter of timing your exercise and capturing how far you've run. Consider this a baseline feature for any fitness device you're considering. While this metric is core for those who race, even casually, it's not always an indicator of fitness levels. In fact, running of any kind is better than not running, and running pace nor the distance you cover, really matters, according to the Harvard Medical School. Just something to consider.

Smart Watch

While not all smart watches also function as fitness trackers, many have the capacity to measure physical activity. The smart watch is worn on the wrist like an ordinary watch and can connect to a smartphone, tablet, or laptop to extract fitness measurements.


When you wear your fitness tracker, you want to be sure the info is connected to an app or smartphone so that the exercise performed is monitored, reported, and ready to access. When you sync your device to an app, this will transfer this data from the tracker to the smartphone or other device you're using.

VO2 Max

VO2 Max, or maximal oxygen consumption, is a way of measuring your cardio fitness. How so? It is a measurement of how much oxygen someone can use in their body during a heavy workout, basically one millimeter of oxygen per kilogram of body weight you use in one minute. Typically, someone has this measurement taken at a clinic, where the intensity of their exercise, on a treadmill for example, increases, according to the University of Virginia's School of Medicine. Some fitness devices, like the Apple Watch 5, can now track this data for wearers. The higher the number, typically, the better as that means your heart can pump out more oxygen — which your muscles can then use.

Water Resistant

Your fitness tracker may come with the notice that it is water resistant. This is not the same as waterproof. This means that you can run in the rain or sweat without ruining a tracker. In some instances, you can swim in water-resistant watches and trackers. The International Organization for Standardization has a certain specification called ISO 22810:2210, and it's worth checking to see if the device you're considering has this rating. The Apple Watch Series 2 and higher carries this rating as does the Gear FitPro 2, Fitbit Ionic and the Samsung Gear Sport. It allows a smartwatch or fitness device to be submerged in up to 50 meters of water for about an hour.

Wearable Technology

A fitness tracker is an example of wearable technology, or more simply put, an electronic device you affix somewhere on the body. Other examples include connected jewelry, headsets, and baby sleep monitors.

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