The Aerospace Resistance Module (ARM) is an aid for preventing bone density loss when astronauts go into microgravity environments, like a spacecraft or the surface of Mars. According to the NASA website, these environments increase bone resorption and decrease bone formation, leading to a rate of bone mass loss ten times that of osteoporosis. The ARM helps prevent bone loss by channeling a piston motion to create a resistance exercise for different musculoskeletal groups. With each stroke, the user produces work by either drawing in or out air through the module. The ARM is configured to work the bicep and forearm, with the ridged side to be placed on the shoulder and a hand around the handle. Constructed out of ABS plastic within the 6in x 6in x 6in printer volume, the ARM is also designed to be modular, with snap/slip fit joints around its base and top to be attached to different components of the astronaut’s clothing to create new exercises. With the ARM, resistance is NOT futile.