Mobile Fitness App for Women Integrated
with Apple Watch and Apple’s Healthkit

Download on the App Store Featured in the App Store






  • SHOCK is a mobile fitness app for women that is based on a unique Shock Training system. The app offers users a brand new way to get fit, tone up, and build muscle. Workouts are extremely personalized; Users can input details about their current fitness level and goals, which helps Shock’s personal trainers match them to a customized training program.

    Over 550 workouts are offered on the app, ensuring workouts are customized for users depending on their fitness level and specific goals.

  • Using high-quality videos and instructions, Shock guides users through each workout and allows them to see their results and set new goals as they grow stronger over time. In addition, the app is fully compatible with Apple Watch, which makes it easy-to-use and completely hands-free. Wrist taps, vibrations, and sound alerts notify users when it’s time to change exercises. They can also turn up the volume and power through workouts jamming to their favorite beats or one of the app’s built-in playlists.

Technology Used




Swift iOS




AWS Services



  • Create a system to make workouts adaptable for a variety of fitness levels.

  • Incorporate personalization in every step to help users track their progress and achieve their goals.

  • Implement a unique methodology to determine target heart rates for each training zone.

  • Provide a hands-free experience for users by fully integrating the app with Apple Watch and Apple’s Healthkit.

  • Implement a real-time tracking feature for heart rate, step count, and distance monitoring.


During the development process...

The Zensoft team used a variety of different solutions in order to optimize the user experience and achieve all project goals. Initially, the plan was to integrate the app solely with Apple’s HealthKit. However, we quickly realized that this solution did not provide the functionality we needed, as it could not give users real-time data. Our developers came up with an alternative solution - using CoreMotion API to track and display step count and distance in real-time.

The next step...

In the project was implementing heart rate monitoring and fully integrating the app with Apple Watch. In order to connect iOS and Watch OS apps to automatically get heart rate data, we developed HeartRateManager. This solution did not allow us to gain full and constant synchronization, so we built an algorithm that would manage instant data flow using advanced caching techniques. The end result was full compatibility with Apple Watch and a real hands-free fitness app.

To make interactions...

To make interactions with the app as seamless for users as possible, we integrated video and music players into the app. We also used caching and optimized the data flow in order to improve the performance and achieve smooth video playing.

The last step...

The last step of the project was testing, testing, testing. In addition to comprehensive back-end QA tests, we also completed a number of indoor and outdoor workouts to ensure that the mobile app and watch app were fully synchronized. Furthermore, we conducted beta-testing with real users and incorporated feedback to polish the app before the App Store release.



The Shock app quickly became the fitness app of choice for women! Within the first few weeks of release, it received thousands of downloads and hundreds of excellent reviews.

As a result of this success, the app was also selected to be featured by App Store and MobileAppDaily.

AppleStore MobileAppDaily