Now Presenting: The Brand New LegExx

Exxentric LegExx

Today marks another major milestone for serious flywheel training. We’re now excited to announce the arrival of the first-ever Exxentric single-exercise device. Here, our CEO Fredrik Correa presents the LegExx.

At the very core of Exxentric it has always been to simplify the training experience, with devices that are easy to understand and that don’t require an advanced strength training technique from the beginning. So that is exactly what we’re presenting today.

We decided that the next step on our journey was to take our refined flywheel training technology and kMeter feedback system and merge it with a traditional leg extension machine.

If you’re already familiar with the general benefits of flywheel technology such as variable resistance and eccentric overload, we feel confident that you’ll appreciate the LegExx.


You might be surprised about the new path we have chosen to take, coming from a 9-year strong history of developing innovative multiple-exercise flywheel devices. However, we really do not see any conflict between multi-joint and isolation exercises. On the contrary, we believe both to be necessary.

Multi-exercise devices like the kBox and kPulley have huge benefits in terms of versatility in various settings. Single-exercise devices, on the other hand, allow you to perform isolation exercises and can be really valuable when you need to focus on a specific muscle group – in the case of the LegExx: the quadriceps.


Like with any traditional Leg Extension machine, the main benefit of the LegExx is that you can maximize hypertrophy by ensuring 100% muscle stimulation in the quadriceps without overcompensating with other muscles, such as the glutes when doing squats.

For injured or low mobility users (e.g. in the ACL rehab process), an additional benefit is that you can get strength gains in the quadriceps without having to worry about posture or complex multi-joint movements.


What sets the LegExx apart, of course, is that it’s built on the latest generation of our flywheel technology. This adds several important benefits:

  • Variable Resistance: The LegExx offers full stimulation over the whole range of motion and in all parts of the quadriceps femoris, both concentrically and eccentrically, thanks to the unlimited and variable resistance of the flywheel. Also, it’s possible to restrict the joint angle, which makes it suitable for clinical usage such as when you want your patients to not exceed a certain knee joint degree.kMeter Feedback System LegExx
  • Eccentric Loading: Thanks to the included kGrip handle of the LegExx, the user (or the physio or trainer) can easily add energy into the concentric phase and overload the eccentric phase. No need for external help to achieve high eccentric loads.
  • Mobility: The LegExx is simple to move due to its practical wheels and absence of a weight stack, which makes it about 80% lighter than a traditional leg extension machine. Hence, making it suitable also for flexible facilities, group training settings, and more.
  • Feedback System: With the LegExx, the kMeter II feedback system is included along with a phone holder, so both the user and trainer can track the power output and other real-time data rep by rep during training.

Since we first showcased the LegExx prototype at the APTA CSM 2020 trade show in the US earlier this year, we have worked intensely with developing and fine-tuning functionality as well as design, based on your feedback. We even added a brand new device color: Space Gray.

Want to learn even more? Then tune in to my presentation of the LegExx below!


As you might have noticed, we decided to abandon the initial “k” in the name of the new LegExx machine, unlike the names of our existing devices.

The “k” in the kBox and kPulley originally stood for “kinetic” (meaning “motion”) as we found it to be a perfect symbol for the multiple-movement nature of those devices.

Therefore, we felt that the new, single-exercise LegExx deserved a new type of name!

For a closer discussion about the flywheel advantages of the new LegExx or an opportunity to try it out, you are always welcome to visit in case you are near any of our offices. Of course, you can also turn to any of our trusted official resellers around the world, of which several already just received the LegExx ready for demonstrations.


I hope you’ll agree that the LegExx marks an important new milestone in the development of serious flywheel training for serious strength training facilities.

I look forward to hearing your feedback as soon as you have a chance to try it out. You’ll love it.Fredrik Correa CEO & Founder of Exxentric

Happy DOMS!

/Fredrik Correa, M.D, CEO

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