Current prototype
Goal
As described in science, the exercise device must achieve the following:
- Fixation from the pelvis downwards via tensioning mechanism
- Rotatable cushion on the pelvis
- Training weight pushing against the back
Effectiveness of the device
Training for two months on my prototype improved my muscle force over 100%. Jump from blue line to orange line, measured on a MedX lumbar extension device.
Frame
The frame consists of aluminum profiles with standard connectors. For the seat a wooden plate is screwed onto an aluminum plate.
Foot unit
The foot unit is mounted on SBR12 linear guides. The attachments for the footrests are 3D printed.
Leg unit
Two straps with thick neoprene fabric prevent the feet from being pushed upwards in the knee area.
Clamping force
A hand winch with automatic load brake is mounted under the seat. A ratched is used to tighten or loosen the tension. It must be removed during exercise.
Training weight
Two gas pressure springs (150N each) are tensioned/relaxed using a lever principle when pressing the back against the back unit. The force can be varied by changing the lever length.
Additional stabilization
An airplane seat belt also helps to fixate the pelvis.
Rotating unit
The tension force presses the pelvis against a rotatably mounted fascia roller. The roller is also necessary to determine whether the tension force is large enough. If the roller does not rotate during the exercise, most of the force is transferred to the multifidi muscles. A rolled up yoga mat serves as a back cushion.