Eugene Saturow Head of Flutter

• Flutter
• Native app development

July 12, 2022 12 min read

Flutter Workout App Development: Technology Advantages

Our Flutter fitness app development expertise and current statistics about fitness and workout apps clearly show there are many smartphone and wearables owners who use mobile apps to maintain a healthier lifestyle, and who can potentially switch to new solutions powered by cutting-edge technology.

The market of mHealth, which covers mobile technologies used in the spheres of public health and medical care, is growing steadily in the US and worldwide. At a growth rate of 11%, it is predicted to reach the size of $130 billion by 2030. 

Choosing a suitable tech stack for app development is an important stage that impacts every aspect of the project. If you consider developing a fitness or activity tracker app, you’re likely choosing between native and cross-platform approach, with Flutter as one of the strongest options.

With 250+ apps for banks, shops, restaurants, and streaming platforms built for over a decade, Surf has gained rich cross-industrial expertise with both native and cross-platform tech stack. In the article, we’ll discuss the pros & cons of fitness app development with Flutter and check what factors define the development cost.

Flutter for fitness app development

Released in 2018 by Google, today Flutter belongs to ‘youngest’ cross-platform frameworks . Let’s see how Flutter, based on the Dart programming language, compares to native development based on Kotlin and Swift languages in such aspects as performance, appearance, and development speed in the workout and fitness applications segment.

Time & cost

Native technologies allow developers to create mobile fitness apps with as wide and complex functionality as possible, achieving very high performance. But these benefits come at a cost: if you want your app to be used on iOS and Android devices, you’ll have to hire two development teams to build two different apps, which means double the amount of management effort, double the amount of possible issues, and difficulty to synchronize the release of both apps. In most cases, apps virtually indistinguishable from native ones can be created by a single cross-platform development team. By the way, the release of the Flutter 3 version extended code-sharing support, making it possible to write the code once and reuse it across all six platforms (iOS, Android, Windows, Mac, Linux, and web).

Cross-platform development not only saves the business from managing two teams at once but also costs less and can be done in less time. For example, 70% of eBay Motors app developers believe Flutter development is two times faster compared to the native one. While Surf’s suggestion to use Flutter for apps for a pharmacy retail chain resulted in saving around 40% of the client’s initial budget set for native development: all 6 apps (iOS and Android for each three brands) were built using a single codebase.

Performance

In general, native apps are characterized by better performance compared to cross-platform solutions. Such frameworks as Apache Cordova or Ionic, interact with the device’s hardware via an additional web layer that has its own performance limitations. At the same time, native apps are often better optimized for specific platforms. 

What makes Flutter stand out among other cross-platform development solutions, is its high performance even in the scenes with heavy animations and graphics. Thanks to the architecture, Flutter apps can communicate directly with the platform’s components without additional layers or code interpreters, which allows apps to demonstrate stable 60 frames per second. Also, since Flutter has its own rendering engine, it helps to achieve more consistent workout and fitness tracking app performance across platforms and devices.

Code maintenance

Maintaining two different native apps can be a challenge, both in terms of finance and team size. A single team can easily maintain Flutter apps, reducing operational costs. This is what led the creators of PUSH Pro training app to choose Flutter when the iOS app’s fans requested it to come to Android. As a result of Flutter migration, the team saw a 20% reduction in maintenance effort, while preserving complete feature parity across the apps.

UI & UX

Since native frameworks use the corresponding platform’s elements in their apps, their appearance always looks consistent with the platform’s interface. Achieving such native look and feel can be hard with some cross-platform frameworks, requiring additional optimization of the app’s elements for each platform. 

Flutter comes with the full support of the latest Material Design and Cupertino visual styles used in Android and iOS respectively. The widgets serving as ‘building blocks’ of any Flutter app automatically adapt their appearance to visually match the platform it runs on, inclusive fonts, animations, and graphic effects, being fully customizable to provide flexibility and expressiveness to the app’s design.

Fitness tracker app features

What features to include in an activity tracker app depends highly on its specifics, such as target audience (general public or pro athletes); type of sports or activities it’s focused on; integrations with other gadgets or wearables, and so on. Let’s take a look at the essential features of any fitness tracking app.

Signup and login

A personal account allows fitness app users to access their data anytime, anywhere, from any device. To make the registration process as easy as possible, consider adding sign-on options via Google, Facebook, Twitter, and other popular social networks — this will also provide users with a convenient way to share their fitness achievements with their friends and subscribers.

Profiling & activity monitoring

Most smartphones come with several sensors that collect diverse data on their users’ physical activity, including a 3-axis accelerometer to monitor speed, a gyroscope to detect a device’s orientation in space, and a GPS sensor to track location. To correctly interpret the sensors’ raw data, it is important to manually input the user’s sex, age, and body measurements. Usually, it is done in a default platform’s health app, such as Apple Health or Google Fit and then shared with other apps.

Both platforms store the collected data in their cloud infrastructure, allowing all of the user’s devices to share and display one comprehensive statistic. By using Google Fit REST API and HealthKit API, fitness app developers can integrate their app with each platform’s health services and access user’s profile and tracked activity data. Particular types of data and visual representation of it are decided by the fitness app specifics, whether it’s a running app, workout diary, or general activity tracker.

Goals & competition

The biggest motivation often comes from competition, either with yourself or others. In the first instance, an option to set fitness goals (miles run, calories burnt, average cycling speed) serves the purpose, allowing users to visually track their progress via meters and charts. The second case can be implemented via interactions with social APIs, such as Strava API, which allows cyclists and runners to compare their efforts and rides data with others. It uses RESTful calls, while responses are formatted in JSON.

Sync with wearables

Currently, there is a wide selection of smartwatches and wearable fitness trackers on the market that come with sensors that complement and extend the capabilities of those used in smartphones. For example, a temperature sensor can measure body temperature during workouts, assessing their effectiveness; an altimeter tracks attitude measuring atmospheric pressure; a heart rate sensor counts heart beat, while a bioimpedance (BIA) sensor measures overall body composition.

Integrating the fitness app with various smartwatches and fitness trackers greatly increases the app’s functionality and richness of data available to the users. Most of the leading wearables manufacturers provide API packages that simplify setting up integration between their devices and fitness apps. For example, Garmin Health SDK allows sharing of real-time training data directly from Garmin wearables to iOS and Android apps. 

Nutrition diary

Fitness tracking apps often come with a food journal that makes it convenient for a user to realize how many calories they consume and burn through exercise to adjust their diet accordingly. Such a nutrition diary can be realized by integration with another dedicated food tracking app to simply source out its data or implemented directly in the fitness app. Integrations with a food database, such as MyNetDiary API, and a built-in barcode scanner should help make food input as quick and easy as possible for users.

Videos & podcasts

If your fitness app is going to be focused on tracking workouts, direct access to exercise videos and training podcasts can significantly improve user engagement. When it comes to built-in video players, the biggest challenge lies in providing smooth playback, especially in cross-platform apps. However, with Flutter, this is not the case. For example, when Surf developed a video-streaming app, the client aimed for a Youtube-like experience. Our choice of Futter allowed easy video player SDK integration, while dynamic resolution and pre-caching let us achieve smooth playback even with a slow internet connection.

Push notifications

Push notifications to a phone or smartwatch can be useful to remind the app’s users about upcoming workouts and notify them when they complete their daily activity goals. It is important to provide extensive customization options for these notifications, since an excessive amount of reminders, as well as their absence, can negatively impact user engagement.

Fitness app development costs

The expenses for app development is made up of four basic elements:

• Business analysis that defines the app’s functionality, target audience; use case scenarios, and business goals.
• UI/UX design that includes creating every element and screen of the app, as well as a clickable app prototype.
• Coding, QA, and testing. The main stage of the app’s development involves writing the app’s front and backend, testing, and bug fixing until the app is ready for release in stores.
• Project management. The entire development process is overseen by a project manager who ensures that every stage is completed in time and delivers expected results.

For example, the cost of fitness tracker app development lies within the $150,000 — 400,000 range and depends on the app features, design, and integrations. While using a fixed-price model allows a development team to come up with a more or less accurate figure and precise list of features before starting development, you may get trouble with later changes and adapting the project to fast-changing market requirements and demands.

That is why we at Surf consider the time & material model to be superior — the project is given only an approximate initial estimation and then broken down into stages (sprints) — the client pays only for features implemented during a sprint, providing developers the flexibility necessary to adapt the app to the fast-paced digital landscape. Read more on app development estimation in our article. 

How to cut down the expenses

To minimize the cost of mHealth app development without compromising functionality and quality, consider these tips. 

Go cross-platform. Even though the hourly wages of Flutter app developers can be slightly higher compared to those using Swift and Koltin, using a cross-platform framework essentially means developing one app for Android and iOS, minimizing expenses on management and salaries of two separate teams of native developers.

Start with MVP. Instead of developing the app with a whole set of features right away, consider starting with a Minimal Viable Product that includes only the core functionality of the app. This way you can test your project concept without significant expenses, gather feedback from users, and adjust the project’s specifications accordingly.

Outsource development. The location of developers significantly affects their wages. For example, hourly rates of developers in the US are $90-100, while engineers of the same qualifications in Western Europe have hourly rates of $40-50. In today’s world of remote working, hiring engineers abroad allows US-based startups to save on writing app’s code without compromising on quality. Learn more about how to hire the best developers for mHealth app in our dedicated article.

Use automation. By using solutions to automate routine coding and testing tasks, you can effectively cut down the number of development hours or let the developers devote them to more demanding and creative tasks. In Flutter app development, Surf uses several of its homegrown solutions that make the process more efficient. Surf Gear is our set of libraries and tools optimizing development, continuously maintained and upgraded by the Surf team. SurfGen is a solution that generates routine app code decreasing the time required to code app’s service layer by 3-4 times. While our Elementary library helps developers create apps adhering to the principles of Clean Architecture that divides apps’ modules into blocks, decreasing the maintenance effort, and a number of revisions.

Summing things up

As more and more people adopt digital technologies to monitor physical activity and improve their wellbeing, the demand for mHealth apps, such as workout and fitness trackers, sees significant growth. The diversity of sports and trends opens great possibilities for fitness apps to build a loyal audience and monetize their services.

If you think about developing a fitness app and explore ways to cut down costs without sacrificing performance and usability, consider building it with Flutter. Many Flutter projects achieve a code sharing rate of 95% or higher, which results in significant cost savings at both stages of development and post-release maintenance.

As a Google-certified Flutter app development company, Surf was an early adopter of the technology and created numerous apps in the spheres of banking, e-commerce, food tech, and digital media. Our open-source solutions make Flutter development faster and more efficient, contributing to the framework’s community.