FLEX Stronger 4+

Velocity-based Training (VBT‪)‬

Kinetic Performance

Designed for iPad

    • 4.8 • 8 Ratings
    • Free



Revolutionise the way you train and prepare in the weights room!

The FLEX Stronger app syncs to a FLEX barbell sensor to deliver real-time feedback straight to your device.

Track, manage and review training performance just like elite and professional athletes right across the globe, through the Major Leagues, UFC, Premier League and Olympic institutes.

Developed by the team at GymAware, FLEX packages everything we learned from delivering gold standard products to the pro ranks into the only VBT system developed specifically for individual use.

The smartest system on the market, FLEX automates your entire training experience. Select an exercise. Load some weight. Lift. Completely wireless. No calibration, adjustments or exercise creation required.

Perfect for individual athletes, remote coaches and personal trainers.

*Performance Metrics & Targets*

Precise and immediate feedback on Mean and Peak Velocity, Mean and Peak Power, Distance, Height, Eccentrics, Position and live bar path tracing.

Set targets on key performance metrics to benchmark effort across your session.

*Group Training*

Add other lifters into your session for group training with up to three people. Complete regular training, pre-programmed workouts or even the 1RM prediction with your group.
Training partners who complete sessions with you can collect and store their data in their own profiles once the session is done.

Training partners can be added or removed from sessions at any time.

*Video Mode*

Switch to video mode and record your set with synced data overlaid on the saved file. Send to friends, coaches or share online.

Handsfree start and stop. Set your device up and lift. Your video will start, stop and crop to capture the set you just completed.

*Automated Workouts*

Complete workouts that step you through the entire program, from exercise and weight changes to targets and rest times.

*Create, Share and Download Workouts*

Create custom workouts directly in the app. Let FLEX run you through your new program, or share them via our Community feature with training partners or clients using FLEX.

Looking for inspiration, download sessions from any of your connections in Community and complete them yourself. Set targets based on their results and compete and compare over the same workout.

*1RM Predictions*

Use the automated 1RM prediction protocol to gauge current strength and readiness levels without an actual 1RM attempt.


There are no limits in the FLEX app. Start regular sessions and add in training partners, or start a pre-programmed workout. Background the app and switch on your favourite tunes. Browse your historical results in the middle of your training sessions. Whatever you need is accessible any time.


Create connections in the FLEX community so you can browse their training history, download sessions (complete with their results), send workouts, train in groups. View session data live as it is uploaded set by set, and interact with fist bumps and comments directly on the platform.

*Store and Review*

All your data is stored and reviewable in History right in your app. Data is securely backed upon our servers and retrieved on your device at any time.

What’s New

Version 2.1.6

In this version, you should notice that you are spending less time waiting around for things to happen. We’ve improved the login process, and reduced time to load the exercise list and video list screens.

We also fixed a problem that caused a session edits not to be saved.

Ratings and Reviews

4.8 out of 5
8 Ratings

8 Ratings

Hudsy86 ,

Happy buyer

The unit shipped quick enough and after a bit of playing around I figured out how I like to use the app best. My workouts are far better compared to not having Flex. Can’t imagine going back to training without it.


Great app, great device

Great training feedback and helps get the most out of sessions. So easy to use. Even has a social function so I my friends can see my sessions and comment.

spuddy0009000 ,

App crashes frequently

I’m sick of the app crashing in the middle of a workout. I lose my stats/progress and have to restart the workout. Sort the app out ASAP!
Consider including an option to continue favourite workouts that have not been completed.

Developer Response ,

Hi, we have just released a new app update which fixes this issue. Testing and developing can be hard so if you ever find bugs or have any feature ideas, please reach out to us at info@flexstronger.com

App Privacy

The developer, Kinetic Performance, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer's privacy policy.

Data Linked to You

The following data may be collected and linked to your identity:

  • Location
  • Contact Info
  • User Content

Data Not Linked to You

The following data may be collected but it is not linked to your identity:

  • Identifiers
  • Diagnostics

Privacy practices may vary, for example, based on the features you use or your age. Learn More

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