Overload motions with flywheels and inertia
Flywheel training is a unique way to overload movement patterns with kinetic energy, unlike in traditional weight lifting where the resistance is determined by weight and gravity. The first references to flywheel training lead back to the 18th of century. Unfortunately, not many articles of usage can be found. However, at the beginning of the 20th century, mankind discovered a new industry that came along with a new challenge - atrophy and bone loss in microgravity, i.e. space travel. Today we are witnessing how flywheel training is being applied to professional sports, rehabilitation, health, fitness, and even in space by astronauts.
Researchers Hansen and Lindhard conducting the first study related to flywheel resistance training at University of Copenhagen in 1924.
ESA astronaut Frank De Winne using the Flywheel Exercise Device to strengthen back, shoulder and arm muscles on board the International Space Station in 2009.
The first prototype of the kBox by Exxentric's co-founders M.D. Fredrik Correa and Marten Fredriksson in 2005(?????).
Exxentric Jet Black campaign in 2020.


Legendary approach to fitness
Flywheel training explained by respected researchers.
Credit: E3 Rehab
Cover the full spectrum with a few flywheels
Add variable resistance to hundreds of different motions by adjusting the flywheel's size, and the inertia of the previous concentric pull.
force/time graph of 1. bodyweight countermovement jump; 2. heavy barbell squat; 3. light resistance flywheel squat; 4. heavy flywheel squat.
Deload weight by stopping the motion
The Exxentric flywheel technology is a revolutionary way to train without a spotter. Since the resistance is created by inertia, even if you challenge your 1RM and fail, the tension will quickly disappear. What's even more astonishing, humans are eccentrically (when muscles lengthen) stronger than concentrically (when muscles shorten). Therefore, flywheel training provides a safe solution to attack the strongest part of the movement and that creates an even harder stimulus for our bodies to adapt.
force/time graph of how resistance ends once the inertia ends
Instant feedback
The kMeter is a scientifically validated feedback system, which measures flywheel rotations and provides detailed force and power output figures, easily accessible through a mobile app. This system is intergrated into kBox4 Pro & kBox4 Lite, and available as an add-on for the kBox4 Active.
Portable toolbox of eccentric overload
To provide modern, well-rounded training solutions, gyms typically spend enormous money to obtain fitness equipment that requires a lot of space for storage. Instead of gravity forcing the weight down, let the inertia take control.


  • Concentric power determines the eccentric overload
  • Add resistance to thousand different motions
  • Compact, light, and portable
  • Adjustable range of motion
  • Train 1RM without a spotter
  • Increased hypertrophy
  • Various resistance
  • Motion freedom
  • Easy to use
Used by professionals everywhere
Which direction you want to overload?
With years of experience and sound scientific support, the kBox4 purposes the advantages of unlimited & variable resistance and capacity for eccentric training, into a setup that comfortably accommodates movements & exercises in a vertical & lateral direction.
  • Build in multiple sizes, materials, and weights
  • Included Angle Adjuster for lateral movements
  • Choose Harness, Hip Belt or kBar as your attachment
The kPulley is a series of flywheel training devices, ideal for users that want to engage in rotational and lateral exercises during flywheel training. It can also act as a perfect complement to existing setups with a kBox system.
  • Highly-durable basketball hoops
  • Tempered glass backboards
  • Adjustable height settings
Seen on Social Media
Recent TikTok posts with the #exxentric hashtag.
Frequently asked questions

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