An abdominal muscle exercise machine that generally contains a diagonal member with an adjustable seat and a backrest and a pivot member that pivots with respect to the diagonal member. A chest push can be mechanically coupled to the pivot member through an adjustable force multiplier. An optional counterweight can be placed near one end of the pivot member to lighten the force, or an optional load weight can be placed near the other end of the pivot member to increase the force. The pivot member can be constructed to telescope or otherwise adjust for different body sizes. The machine provides a smooth exercise where the top and bottom portions of the body move together in a linked fashion. The machine of the present invention works without heavy external weights.