Concept based on isometric contractions

It's simple but still had to think about it! The involvement of previous muscle chains occurs by advancing the two wheels, once stabilized hold the position in straightness column. This seems to require a large muscle work, to be repeated several times during a workout. Quotididiennement used the 'casing' 'of the trunk and the abdomen is carried out by muscular contractions isometric (without change in length of the muscle). This is in my opinion the usefulness of the device, the concept of repetitive movement chained leaving too much compensation for the average user.
The carpet comes with merit a triple thickness in order not to impact the ball on the ground, which could create pain in the patellofemoral joints.
Ultimately, and this is what I remember, it is a device very compact and intrinsically possessing a true utility, the travel bag has better behave themselves!