Flywheel training is a unique development in sports and physical therapy. Training with a flywheel is also called kinetic training. Instead of traditional weights, the training is done with a rotating disc. In the concentric phase, the flywheel starts and accelerates by means of pulling a webbing. When the webbing is completely unwound, so much kinetic energy has now been built up that the webbing will roll itself up again, just like the well-known yo-yo. The goal is to bring the flywheel to a stop and then start it up again with a concentric movement. So the resistance you experience is not caused by gravity, but by inertia, also called mass inertia or (rotational) kinetic energy. The harder you pull, the harder the flywheel will spin and the more inertia will occur. To then brake the flywheel you will need quite some (eccentric) force!