Dev Journal #1 - Yet Another Fitness App?!?


I know. It’s been overdone and the world doesn’t need another exercise app. But I need you to hear me out. Exercise tracking and I go way back. Ever since I started weight training, I’ve always kept a memo of my training logs on my phone. Every time I pulled out my phone to log, I kept wondering if I can find a smarter solution to track my workout sessions. In 2018, I built a prototype device to track the big 3 movements in weight lifting. It was capable of counting reps for deadlifts, squats and bench press using 9-DOF sensors and displaying the results to the connected mobile device via Bluetooth in real-time.

My ultimate goal was to completely automate the process of tracking weight lifting. Ideally, I wanted the user interaction to be as minimal as possible so that the athletes can just focus on the workout without having to adjust the device settings in between sets. But the project came to a halt when I couldn’t find a way to automatically track the weight changes in barbells, cables and dumbbells. To be able to record the changes in weights, it will require some sort of modification on the gym equipment itself. Now all of a sudden, the scale of the project has become much larger. Do I manufacture custom weight plates and dumbbells with built-in sensors and BLE (Bluetooth Low Energy)? Considering this is going to be used in a commercial gym environment, these weights are not going to be handled gently and the electronics inside could be easily damaged if not housed properly. BLE consumes considerably less power but they still will eventually need charging which means I also need to build a solution for wireless charging when plates and dumbbells are sitting on the rack. Also with hundreds of weights with built-in BLE devices, I would need to set up a mesh network to allow communications between them and the user. Each one of these ideas are super interesting engineering problems that I might want to revisit one day. TLDR; My prototype device was not enough to replace pen and paper.

Since then, my interest has shifted to bodyweight exercises and once again, the idea of tracking skill progression has crossed my mind. Bodyweight exercises are not completely free from having to track weights. Ankle weights and weighted vests can be worn during exercises and a lot of athletes perform weighted pullups and dips with belts around their waist during training. So automatic tracking solution is still off the table. In fact, bodyweight training requires a wider range of data fields to describe each exercise making automatic tracking even harder because the movements are much more detailed than weight lifting. It would probably make more sense to use a computer vision from video recordings than extrapolating data from wearable sensors because body leverage and angles are easier to detect from images than from analyzing data from sensors attached to each joint in your body. TLDR; Automatic tracking is probably not feasible for general audience (yet!!!)

I’ve seen few calisthenics apps that build workout routines, provide virtual coaching or exercise tutorials. But I have yet to find one that lets you track calisthenics skill progression with body leverage. I think this is most likely because street workouts are not mainstream so there isn’t a huge demand for it. But what the heck, I will build one.

The key features will include:

  1. User profile with basic body stats
  2. Exercise logging that is catered specifically to calisthenics exercise
  3. Hall of fame to discover local legends (or become a local legend)
  4. Calculate PR or predict timeline to achieve skills based on current stats

Having said that, nothing is set in stone. At the end of the day, this is just another side project. And we all know what that means. 🙈

What is your favourite fitness app and why does it suck? TLDR; I am building an app for tracking calisthenics skills. Yes, it’s manual logging. Yes, I am still doing it.

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