apparatus for exercising a user &# 39 ; s abdominal muscles and / or back muscles . this exercise apparatus includes a dynamic means in the form of an upper frame which is pivotally attached to a lower form . with the use of the user &# 39 ; s abdominal and / or back muscles , the dynamic means produces a forward folding movement and a return straightening movement . a framework means in the form of a vertical frame affixed to a horizontal frame which maintains the vertical frame in an upright position supports the dynamic means . this exercise apparatus also includes a resistance means for opposing the forward folding movement and / or the return straightening movement . various resistant means include fly wheel - fan , electro - magnetic and weight stack .