Exercise machine

1. An exercise machine comprising:

a frame;

a piston and cylinder assembly which is supported by the frame;

an apparatus for establishing a controlled fluid pressure inside the cylinder;

a first actuator which is movable by a user from a first rest position against a first resistance force which is dependent at least on the fluid pressure inside the cylinder, to cause telescopic movement of the piston and cylinder assembly, the first actuator including at least a first device which is movable by the user and a first mechanical advantage system connected to the piston and cylinder assembly whereby movement of the first device by a first distance causes corresponding telescopic movement of the piston and cylinder assembly by a second distance which is smaller than the first distance; and

a second actuator which is movable by the user from a second rest position against a second resistance force which is dependent at least on the fluid pressure inside the cylinder, to cause telescopic movement of the piston and cylinder assembly, the second actuator including at least a second device which is movable by the user and a second mechanical advantage system connected to the piston and cylinder assembly whereby movement of the second device by a third distance causes corresponding telescopic movement of the piston and cylinder assembly by a fourth distance which is smaller than the third distance;

wherein the fluid pressure in the cylinder is increased by the telescopic movement of the piston and cylinder assembly, and exerts a force which tends to extend the assembly and restore the first actuator to the first rest position and the second actuator to the second rest position,

wherein the piston includes a piston head which is mounted for reciprocating movement inside the cylinder and a piston rod which is attached to the piston head and which extends from the cylinder, the piston rod having a hollow interior, a sealed end which is remote from the cylinder and an open mouth which is located inside the cylinder whereby the fluid pressure in the hollow interior is the same as inside the cylinder, the fluid pressure inside the cylinder on opposed sides of the piston head being the same, and

wherein the increase in fluid pressure in the cylinder due to the telescopic movement of the piston and cylinder assembly, is dependent on the extent to which the piston rod extends into the cylinder.

2. An exercise machine according to claim 1 wherein the piston and cylinder assembly includes first and second ends and wherein when the assembly is caused to move by the first actuator, the first end engages with a first support on the frame, and the second end moves relatively to the frame, and wherein when the assembly is caused to move by the second actuator, the second end engages with a second support on the frame and the first end moves relatively to the frame.

3. An exercise machine according to claim 1 wherein the apparatus includes a fluid pump for pressurising fluid inside the cylinder and a pressure relief device for reducing in a controlled manner the pressure of the fluid inside the cylinder.

4. An exercise machine according to claim 3 wherein the apparatus is positioned inside a housing which is mounted to the frame.

5. An exercise machine according to claim 4 wherein the housing forms a footpiece at a lower end of the frame and which includes a first control mounted to the footpiece for controlling the fluid pump and a second control mounted to the footpiece for controlling the pressure relief device.

6. An exercise machine according to claim 1 wherein the apparatus includes a gas-pressurised cylinder.

7. An exercise machine according to claim 1 which includes controls for controlling the fluid pressure inside the cylinder.

8. An exercise machine according to claim 7 wherein the controls are foot-operated.

9. An exercise machine according to claim 1 wherein the frame is elongate with a lower end and an upper end and which includes at least one support member to support the frame at an inclined position relatively to the ground.

10. An exercise machine according to claim 9 which includes a seat which is mounted to the frame between the lower end and the upper end thereof.

11. An exercise machine according to claim 10 which includes a footpiece at the lower end of the frame.

12. An exercise machine according to claim 11 which includes at least one control for controlling the resistance force.

13. An exercise machine according to claim 12 wherein the at least one control is mounted to the footpiece.

14. An exercise machine according to claim 9 wherein the inclined frame has an upwardly facing front side and a downwardly facing rear side and wherein the first actuator further includes a support which extends from the upper end of the frame at least partly over the front side and the first device includes at least one handle which is supported by, or which forms part of, the support and which is connected to the first mechanical advantage system.

15. An exercise machine according to claim 10 which includes a structure which is pivotally mounted to the seat, at least one formation on the structure against which at least one foot of a user, on the seat, reacts, and at least one link between the structure and the second actuator whereby movement of the structure relatively to the seat results in movement of the piston and cylinder assembly.

16. An exercise machine according to claim 1 wherein the frame is elongate with opposed upper and lower ends and opposed side walls which form an enclosure and the piston and cylinder assembly is supported inside the enclosure.

17. An exercise machine according to claim 16 which includes a seat which is mounted to the frame between the upper and lower ends thereof, the seat being movable between an operative position and a storage position at which the seat overlies a first part of the enclosure and of the piston and cylinder assembly and a footpiece at the lower end of the frame which is movable between an operative position and a storage position at which the footpiece overlies a second part of the enclosure and of the piston and cylinder assembly.

18. An exercise machine according to claim 1 wherein the first device includes first and second handles which are positioned at an upper end of the frame near respective opposing sides of the frame and which are connected to the first mechanical advantage system.

19. An exercise machine according to claim 18 wherein the second device includes third and fourth handles which are positioned at a lower end of the frame which opposes the upper end, and near opposing sides of the frame, and which are connected to the second mechanical advantage system.