or both tubes with pins or rods passed through the holes or alternatively by providing the innermost tube with spring loaded pins that extend through holes in the outermost tube in another embodiment the apparatus includes handles positioned in a predetermined position along the support structure or extending outwardly from the bench so as to provide additional support for the user the height of the apparatus from the floor to the top of the arcuate bench is typically in the range of between about twelve inches to about thirty inches more typically between about sixteen and twenty inches and ideally around eighteen inches other aspects of this invention which should be considered in all its novel aspects will become apparent from the following non limiting example with reference to the accompanying drawings referring now to fig1 7 of the drawings the exercise device embodying the invention generally is designated 10 device 10 comprises frame elements 20 and 30 which are connected by folding cross brace 40 bracket 50 pivotably mounted near the upper ends of frame elements 20 and 30 supports bench 60 during exercise bench 60 rocks back and forth in response to the user 39 s contraction and relaxation of selected muscle groups a detailed description of the structure of device.