Overload movement patterns with flywheels that create a kinetic energy.
At the beginning of the 20th century, mankind discovered a new industry that came along with an unseen challenge for the human race - atrophy and bone loss in space travel as the micro-gravity conditions removed the physical demands from astronauts and therefore their bodies become weaker and weaker over time. To overturn this issue and keep the space travelers healthy, a new industry skyrocketed together with them - flywheel training. Today, we are witnessing how flywheel training is innovated in professional sports, rehabilitation, health, and fitness all around the world.


With years of sound scientific support, the kBox4 purposes the advantages of unlimited & variable resistance and capacity for eccentric training, into a setup that comfortably accommodates movements in a vertical & lateral direction.
The kPulley is a series of flywheel training devices, ideal for users that want to engage in horizontal, rotational and lateral exercises during flywheel training. It can also act as a perfect complement to existing setups with a kBox system.

What is flywheel training?

The resistance in the flywheel training is created by inertia in a similar fashion to the yo-yo toy. The harder you throw it, the harder it will come back.
Physical therapist Dr. Sam Spinelli from E3Rehab.

Train without a spotter

Since the resistance is controlled by the user's power outputs, even if he/she fails while attempting a rep, the inertia will quickly disappear and leave the participant without weights on the body, unlike it would be with traditional weight lifting.
A force/time graph of a participant finishing a set of Kbox and barbell squats. Source: Hawkin Dynamics 

How muscles work?

Eccentric muscle contraction is when our tissues lengthen as we are going deeper into the motion. For instance, when we lower a barbell, the muscle fibers in the biceps muscles stretch.
The isometric phase is the amortization part of the movement that occurs with the least speed as our bodies transition the forces from the eccentric phase into the concentric.
The concentric phase of the motion is when our muscle fibers shorten to create power. For instance, while we are sitting, our tissues are already at the maximum length, and as we stand up the muscle fibers shorten.

Eccentric overload

As numerous studies have shown, human mucles can lower more weight (eccentric contraction) than we can pick up (concentric contraction). This is a safety mechanism for our bodies to control the energy that we gained from the movement and therefore we can be more resilient to injuries and execute our motions more efficiently. Accordingly, flywheel training devices allow users to overload the strongest part of the motions and place higher demands on our bodies to adapt.
A force/time graph of the national champion weightlifter Erik Jonsson performing a 180 kg max effort barbell squats vs. 0.280 kgm² flywheel squats. Source: Exxentric