Exercise machine with unstable user support

A rotary torso exercise machine, comprising:

• a main frame;
• a lower torso support rotatably mounted on the frame for rotation about a first, vertical axis between a forward facing position and opposite left and right swiveled positions, the lower torso support confired to support a lower torso of a user;
• an upper torso support mounted on the frame for supporting the upper torso of the user in a fixed position while the lower torso is rotated;
• the lower torso support comprising a base mounted on the frame for rotation about the first, vertical axis between left and right swiveled positions and the forward facing position, and an unstable user support platform pivotally mounted on the base for rotation in at least two opposite directions between a centered orientation and first and second tilted orientations about at least one second, non-vertical pivot axis;
• and
• a stop assembly between the base and user support platform configured to limit tilting of the user support platform to a predetermined angular range between the centered position and each tilted orientation.

An exercise machine, comprising:

• a stationary main frame having a forward end, a rear end, and opposite sides;
• an exercise arm assembly movably mounted relative to the main frame and having a user engaging portion which adapted for engagement by a part of a user's body to perform an exercise when a user is supported in an exercise position on the user support assembly;
• a user support assembly mounted on the main frame and adapted to support a user in an exercise position during an exercise;
• the user support assembly comprise a base pivotally mounted on the main frame for rotation above a first pivot axis, an unstable user support platform, and a pivot connection between the user support platform and the base configured for allowing free rotation of the user support platform about at least one non-vertical tilting pivot axis in at least two opposite directions between a centered user support position and first and second tilted end positions;
• and
• a stop assembly between the base and user support platform which defines the respective first and second end positions and limits tilting movement from said centered support position in each direction to a predetermined angular range.