Apps for Fitness Integrated with Wearables. How to Create an Activity Tracking App

The article was updated on December 02, 2020.

Wearable technology is invading all spheres of life, and nowhere more so than in healthcare and sports.

According to, global end-user spending on wearable devices is predicted to reach $63 billion by 2021. Obviously, for most consumers, the idea of generating personal health and fitness data while working out, taking a morning run, or riding a bicycle looks highly enticing. Today, wearables are tracking burnt calories, heart rate and blood pressure, monitoring sleep patterns, sun exposure, and much more.

The wearable tech boom opens a doorway of opportunities for mobile app developers. Even though wearables can provide continuous data flow and can make individual data collection much more accurate, they need apps running on end-user devices to make sense of users’ personal data.

In this article we describe what activity tracking utilities are available at the moment and what features a great fitness application should include. Before we proceed, though, here are some interesting market stats for wearables that we believe you should take into consideration. Read on to learn more!

Wearables market statistics

So why is wearable application development such a lucrative business niche? These figures spill some light on the subject.

Statista suggests that by 2022, as much as 900 million people will be using wearables. also predicts that the number of wearables globally will double in 2022. Smartwatches will continuously grow in popularity with their number reaching 150 million in 2022 – which outnumbers PCs and smartphones, for comparison.

Apps for fitness enjoy the highest retention rates of all the existing application types, as revealed by Flurry research. Apparently, users tend to stick to their apps of choice rather than switch to other solutions.

As per, the joined revenue of the world’s biggest 10 health and fitness app vendors reached $327 million in 2019 after having grown by 61%. Thus, we can predict that the creation of iWatch Apps, as well as Android Wear Apps will be increasingly gaining momentum.

Examples of apps for smartwatches and trackers

Let’s now explore some of the most widespread fitness tracking apps more closely. Below is an overview of consumers’ top choices for analyzing data collected by smartwatches, wristbands, and other wearables.

Google Fit

Google Fit tracks two vital metrics: users’ pulses and the amount of their active time throughout their day. The app provides users with some actionable exercise tips helping them lead healthier lifestyles and tracking their overall “Move Minutes”. Created in cooperation with WHO (The World Health Organization), Google Fit can sync with other fitness apps, such as NikeRunClub. If you want Google Fit to monitor your nutrition, you will have to enter this data manually. 


Samsung Health

Samsung Health has impressive gamification features and offers users a range of options on making their workouts fun and exciting. For example, users can engage in competitions to stay motivated, or even join worldwide tournaments.

The app offers detailed daily stats on how users’ nutrition, activity, and stress levels have changed during the day, or on a more long-term scale. It also offers them work out tips based on their personal data. The app is compatible with both IOS and Android. 

Apple Health

Installed by default on most iPhones or AppleWatches, this app can be easily paired with other popular fitness trackers. Apple Health monitors your body to identify the amount of burnt calories; it also counts how many steps you’ve walked, the distance you’ve covered as well as your pulse at rest or during your workout. It also monitors your sleep patterns, and enables you to add other activities you want to monitor to the list, such as standing minutes. The app is intended for iOS 11.3.

Polar Beat

This app offers an enormous range of activities it can track.  Users can choose from a list of about 100 different sports and fitness activities, for example, rowers and mountain climbers will surely find the app useful. Users can also set specific fitness goals that they want to achieve.

When synced with wearable fitness trackers, the app tracks core fitness metrics; it also enables users to share their results with their peers on social networks. Polar Beat also features a 5-minute Fitness Test to assess your fitness and a Running Index to estimate your running efficiency. The app is compatible with most Android devices and iOS 12.0.



A fitness tracking app of choice for most runners, NikeRunClub has a vast pool of loyal users, and for good reason – it offers guided coaching sessions helping runners to run at their best. By listening to a voice through the headphones, users can get encouragement and inspiration as they run, and focus on their mental and bodily sensations.

The app collects metrics like running speed and distance, users’ location on the map, heart rate and elevation. You can also share your running playlists and form an online community of equally engaged runners. The app is compatible with most Android devices, iOS 11.0, and watchOS 4.3. 

Apart from smartwatches and wristband fitness trackers, wearable fitness apps enable you to load data from other devices, such as smart scales or heart rate monitors to get even more revealing fitness data.

In a nutshell, most of the apps on the fitness wearable market are meant for tracking running data, counting calories and sleep control. A vast segment of apps offer work out tips and examples. There’s also a niche of apps targeted at users with serious health conditions, such as asthma or Parkinson’s, helping them track their symptoms and prevent hospitalization by taking timely action.

Technologies used in fitness tracking apps

So how do wearable fitness trackers work? To build a wearable fitness app you must use the software and hardware components. Below we will take a closer look at what usually constitutes the hardware of the fitness tracker.

Components of the fitness tracking hardware

Wearable devices contain specially designed tiny microcomputers, known as SoCs (System-on-a-Chip), like ‘Curie’ module from Intel or Snapdragon Wear from Qualcomm. They function with low-power motion sensors and a battery which can last for weeks while continuously monitoring different activities and health parameters of your body. Wireless technology like Bluetooth allows wearables to send this real-time activity data to other devices.

Most of today’s fitness trackers are packed with different sensors:

3-axis accelerometer and gyroscope are the movement tracking sensors. Although often confused with one another, they have distinct differences. The accelerometer is intended for monitoring speed, while the gyroscope is also capable of tracking the position of a device or a fitness band, its rotation and orientation in space. 

GPS sensors monitor the position of a wearable fitness device or a smartphone and are used to track location and estimate the covered distance. Because of its heavy battery drain, most manufacturers choose to exclude this feature. Moreover, if a tracker can be paired with a smartphone, it’s better to use GPS available on the smartphone.

Altimeter is a sensor for tracking altitude. Technically, it doesn’t measure the altitude in itself, but tracks atmospheric pressure to calculate the altitude above the sea level. The higher you climb above the sea level, the lower the atmospheric pressure.

The raw data collected by these sensors can then be converted into a number of steps taken or calories burnt by applying complex algorithms. Of course these algorithms cannot rely solely on the data provided by the sensors, personal information like age, gender, height and weight are essential to produce accurate results. Most fitness tracking apps come with the ability to add this data when a user is asked to fill out profile information.

Temperature sensors – as people work out, their bodily temperature increases. The sensors designed for measuring the release of bodily heat can provide useful data on work out efficiency.

Skin galvanic reaction sensor is another type of appliance used for measuring bodily temperature. This sensor type helps estimate the stress level and the overall state of a person’s health.

Heart rate monitors – mounted into wristbands, these sensors use optical rays to measure the user’s heart rate by tracking the pulsation of blood through the person’s skin, and counting the constrictions of the heart muscle.

Bioimpedance sensors – an advanced sensor type that sends microcurrents through a person’s body and measures its composition. The data obtained in this manner helps us estimate the state of a person’s health and vitality.


Tools for building fitness tracking apps

In regards to the fitness app development itself, developers now have a whole set of tools, like SDKs and APIs, at their disposal that let them write fitness applications compatible with a variety of wearable devices. It is essential for a fitness app to be able to pull activity data, not only from a smartphone, but also from any wearable gadget out there.

GoogleFit and HealthKit

Built by Google and Apple respectively, GoogleFit and HealthKit APIs are the easiest way to develop wearable fitness apps. These APIs contain all that is necessary to build complete fitness applications which are full of different features, like diagrams, timelines, charts, maps, progress bars, etc. They allow developers to access and process sensor data collected directly on their platforms as well as sensor data sent from different wearable devices.

Additionally, major wearable manufacturers also provide developers with their own APIs for their devices.

Fitbit is a manufacturer of tracking devices and owner of a namesake fitness software. The Fitbit app integrates with other solutions and offers third-party developers an API for building their own applications.

Strava is a web-based service for tracking work-outs. The service has social network features, a selection of apps and a database for recording the results of fitness activities. It also has its own Strava V3 free API with access to data contained in this database.

Withings is a renowned manufacturer of fitness devices such as tonometers and smart scales. Declare yourself a Withings developer, to gain access to their API.

Jawbone UP is a fitness tracker with classic features like measuring sleep cycles and the number of steps. The tracker has a proprietary mobile wearable fitness app, and also has an API and an SDK for developers that want to build their own apps for fitness.

Garmin is a famous manufacturer of devices like smartwatches, fitness trackers, GPS navigators, running dynamics pods, pulse oximeters, etc. Its fitness app, Garmin Connect, syncs with these devices, and an SDK is also available for those who want to develop apps for Garmin wearables.

Don’t forget about UX

Before diving into more technical stuff, let’s talk about the basic features of a great fitness application. They are not related to activity tracking, but are essential for providing top-notch UX:

#1 – Personalization

A personal account is absolutely vital for a fitness app. Adding personal information like age, gender, height and weight gives the fitness app the ability to accurately track your activities.

A personal account will also allow a user to customize the application to their needs:

  • plan personal exercise routines
  • save statistics
  • synchronize it with a social network account
  • goal setting (such as losing weight or a new distance to run)

#2 – Social sharing

Integration with social media accounts allows users to share their accomplishments and even creates competition among others within the same community. This helps people stay motivated and encourages them to raise the bar and to achieve more.

For example Nike+ Run Club gives its users the ability to share their runs with their friends via Facebook, Twitter or Path. Friends can “Cheer each other on” while they are running.

#3 – Notifications

Regularity is the key to success in sports. Push notifications and in-app messages are very useful tactics which help keep users motivated toward achieving their goals. A fitness application can remind its users about the next workout, or it can send messages to its users which will encourage them not to stop while they are running and to keep going.

#5 – Custom workout routines

This feature allows a user to design and manage their own workout program by selecting specific exercises its frequency and intensity, and even setting a recovery time. A workout program may include different activities: warm-ups, aerobic fitness, core strength exercises etc. In order not to get bored, a user can always alternate among different activities.

Many fitness apps offer hundreds of workout routines for a user to choose from, but only a few allow a user to craft their own workout routine tailored to their needs and abilities, as it is implemented in JEFIT.


Activity tracking features

Now let’s take a closer look at the features which are the essence of a fitness tracking app. This list is by no means complete. Each new generation of smartphones and wearable devices are released with more features and capabilities:

#1 – Movement tracking

Tracking motion is easily achieved and accurately calculated. Actually, a fitness app doesn’t need a wearable device to count steps, stairs, miles or measure the speed or direction of movement. A set of motion sensors inside a modern smartphone can easily do all of that with high accuracy. They can even distinguish between walking and running.

For example, iPhone7 has built-in barometer, three-axis gyroscope, accelerometer, proximity sensor, ambient light sensor, digital compass, GPS and GLONASS navigations. Apple Health and Google Fit could serve as good examples of such apps that can only rely on detectors built into your phone and don’t rely on any additional devices.

#2 – Geolocation

Geolocation allows an app to determine the user’s location. With this feature, users can track their current position, build walking and running routes and see their achievements and their progress that they have made on the map.

There are many ways to calculate geolocation which includes an IP address, cell phone triangulation, WiFi positioning etc. However, the most trusted and accurate source of location data are services like GPS or GLONASS. The downside to these services is that they cause heavy battery drain.

#3 – Measuring heart rate

There are two types of sensors that can be used for measuring HR:

  • optical sensors shine a light into the blood vessels in your wrist, and then detect the changes in blood volume that occur each time the heart beats and pumps blood throughout the body;
  • bioimpedance sensors measure the resistance of the skin to tiny electric currents. They are more accurate and consume less power.

Both of these methods of measuring HR require direct contact with the skin. That’s why they aren’t usually implemented in smartphones but rather in different types of wearables, like wristbands or smartwatches. On the other hand, as with movement tracking, HR can be measured without resorting to additional devices. For example, Instant Heart Rate allows a user to measure their HR by placing the tip of their index finger on the phone’s camera.

#4 – Calorie expenditure

To calculate how many calories the user has burnt doesn’t actually require an additional sensor. All that is needed is an algorithm and the data that is already available. Actually different apps use different algorithms, which means that they can produce different results. For example, Wahoo Fitness uses an algorithm that includes weight, height, age, sex, and current heart rate.

#5 – Sleep tracking

Sleep tracking apps require an additional tracker such as a wristband that has contact with the body during the night. The tracker will translate wrist movements into sleep patterns, including how long a person has slept and the overall quality of their sleep. As with calories it is not very accurate.

#6 – Sun exposure

Fitness apps can either:

  • predict how long a user should stay in the sun based on UV index forecast. For example, Ultraviolet gives tailored sun exposure advice based on weather conditions, skin type and the current UV index;
  • or it can actually measure sunlight exposure, in which case a wearable device is required with UV sensor, like Violet.

#7 User profile

Since social integration has now become a golden standard, it’s absolutely necessary for fitness app users to set up individual profiles. A profile should contain information about a person’s age, gender, and favorite activities. Users should also be able to access their account and payment settings through their profile.

#8 Dashboards

Wearable fitness apps bring important analytics and insights, and users need visualization tools to read this data. Dashboards should enable users to access info on the amount of calories burnt, distance walked during the day, and other personal fitness stats.

#9 Gamification

Engagement is paramount to ensuring high user retention rates, so it’s highly advisable to introduce gamification features to boost users’ satisfaction and involvement levels. Many fitness apps encourage contests to keep users engaged.

#10 Goals

Achievement is a huge incentive to work out more, and workouts are proved more effective when tied to a measurable goal. Knowing intermediate results, though, helps users stay motivated. Also, nothing motivates you to achieve your goals like publicly declaring them, so users should be able to share their goals with their friends on social networks.


How to get started?

The product discovery phase is the best first step you can take to lay a solid foundation for the development of your app. It includes a functional specification, UX/UI design, and a visual prototype that will give you a clear vision of the end product. On average, this phase takes 4-6 weeks.

The product discovery phase can help you:

  • define a full scope of work and develop a roadmap for the project
  • set a realistic budget for your MVP and plan your resources
  • test the waters with your audience using a visual prototype
  • craft a convincing investment pitch
  • get to know your team

Have a great idea for wearable app development? At Eastern Peak, we have all it takes to build your unique wearable fitness tracker. Still not sure where to start? Book the free consultation with our specialists!

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