Resisting system for making variable mechanical resistance exercises

An exercise machine comprising:

• a base member;
• a first column extending upwards from the base member;
• a first carriage slidably mounted on said first column and movable therealong between at least two operating position;
• an irregular pulley pivotally affixed to the first carriage for rotation through 180° about a pivot axis;
• at least one arm affixed to the first carriage and projecting outward therefrom;
• at least one traction element connected at one end to the irregular pulley;
• a retractable cartridge incorporating a clutch affixed to the base member and having another end of the traction element affixed to the retractable cartridge;
• a computer mounted to the base member;
• a pneumatic piston pivotally connected to the base member and with a piston rod extending upward;
• a second column extending upwards from the base member;
• a cam arm pivotally connected at one end to the second column and having a pulley at a free end thereof and cooperating with the traction element;
• a second carriage slidably mounted on the cam arm and connected to the piston rod, the second carriage including a threaded travelling nut;
• and
• a threaded guide screw cooperating with the threaded travelling nut, said guide screw being driven by a motor supported by the second column whereby translation of the second carriage along the cam arm varies the force needed to raise or lower the at least one arm.