Exercise machine For Use with Lower Body Negative Pressure Box

In a Lower Body Negative Pressure (LBNP) Box comprising a frame adapted to accommodate a lower body portion of a subject, the frame comprising a plurality of spaced-apart rigid members upon which are disposed a pressure resistant material to thereby define a lower body-receiving envelope attached to a pump which creates a lower pressure environment (negative pressure relative to atmospheric pressure), with the LBNP placed in a supine position inside the box, the improvement comprising an exercise apparatus comprising:

• a rectangular base frame;
• an adjustable sliding frame member having opposing first and second sides and mounted on the rectangular frame, wherein
• a position of the sliding frame member is adjustable along the base frame to accommodate users of different heights;
• a four-bar linkage assembly comprising a first pair of spaced apart, parallel bars and a second pair of spaced apart, parallel bars each having a first end and a second end, and wherein said second end of each bar of said first pair of bars is attached at a first pivot point to the first side of the adjustable sliding frame member and said second end of each bar of the second pair of bars is attached at a second pivot point to the second side of the adjustable sliding frame member such that the first and second pairs of bars are alignably positioned across said first and second sides of said adjustable sliding frame member, and wherein said first end of each bar of said first pair of bars is attached to a first support bracket and said first end of each bar of said second pair of bars is attached to a second support bracket;
• a first adjustable foot pedal mounted on the first support bracket;
• a second adjustable foot pedal mounted on the second support bracket;
• a first coil spring and damper assembly attached at a first end to a first adjustable ground pivot on said second end of said first pair of bars and at a second end to the first side of the adjustable sliding frame member;
• a second coil spring and damper assembly attached at a first end to a second adjustable ground pivot on said second end of said second pair of bars and at a second end to the second side of the adjustable sliding frame member, such that each said coil spring and damper assembly provides resistance during a user's cyclic movement of the respective foot pedals through compression of the coil springs;
• a spring-loaded pin detent mechanism for adjusting the position of the sliding frame member to accommodate each user;
• and
• a chair adjustable in both angle and linear distance to apply a resistance force to a posterior side of the user's lower extremities during use of the exercise apparatus.