Exercise apparatus (10) for training a user's abdominal muscles comprises a lever frame (11) linked to a support frame (12) at a pivot (13). The lever frame (11) has first and second arms (14,15) joined at a junction (16) also forming a fulcrum for the lever frame (11). The support frame (12) consists of a base member (22) having a seat portion (23) associated with, and laterally rotatable relative to, the base member (22). The apparatus (10) may be used to perform either simple or compound abdominal muscles training exercises. In a simple exercise, the user∝s abdominal muscles are exercised by pushing the first arm (14) away from the user's body to rotate the lever frame (11) about its fulcrum (16), causing the seat portion (23) associated with the base member (22) to lift and tilt. In a compound exercise, the user's obliques and transversus abdominal muscles are exercised by performing an abdominal twisting motion to cause the seat portion (23) to rotate relative to the base member (22).