NASA’s Advanced Resistive Exercise Device (ARED)

Advanced Resistive Exercise Device (ARED) uses adjustable resistance piston-driven vacuum cylinders along with a flywheel system to simulate free-weight exercises in normal gravity. Studies have found that without exercises like those possible on the ARED, astronauts could lose up to 15% of their muscle volume, which could be difficult or even impossible to regain back on Earth. ARED’s primary goal is to maintain muscle strength and mass in astronauts during long periods in space.

Science Results for Everyone Exercising in space poses unique challenges, but without exercise, astronauts can lose up to 15 percent of their muscle mass, some of it permanently. The Advanced Resistive Exercise Device (ARED) investigation uses a piston and flywheel system to simulate free-weight exercises in normal gravity to work all the major muscle groups through squats, dead lifts, and calf raises.  ARED users see results similar to those from free-weight training, suggesting that it could be an effective countermeasure against loss of conditioning during spaceflight. While ARED’s primary goal is to maintain muscle strength and mass, resistive exercise also helps astronauts increase endurance for physically demanding tasks such as space walks.


The Advanced Resistive Exercise Device (ARED) was designed to address the limitations of the Interim Exercise Device (iRED) and serve as the next generation of in-flight resistance exercise hardware on the ISS. A study compared the musculoskeletal adaptations to 16 wk of resistance exercise training with the ARED to training with free weights (FW) in healthy, untrained, ambulatory men and women. It was proposed that 16 wk of training with the ARED or with FW would result in significant increases in muscle strength, muscle volume, lean tissue mass, vertical jump (VJ) height, and bone mineral density (BMD), and that FW would increase muscle strength, muscle volume, lean tissue mass, and BMD to a greater extent than ARED because of the differences in inertial characteristics of the ARED flywheels and FW.

In ambulatory subjects, ARED training resulted in increases similar to those with FW training for all of the variables measured, the only exceptions being a greater rate of increase in squat (SQ) strength from midtraining to posttraining and a greater rate of increase in VJ height in the FW group. These device-dependent differences might relate to the inability of the ARED flywheels to mimic inertial characteristics of FW throughout the full range of resistances, or they could relate to differences in the biomechanics of exercise between the two devices. Given these findings, and considering the effectiveness of FW training at mitigating bed rest–induced deconditioning, we expect that ARED training will be a more effective countermeasure than iRED training against musculoskeletal deconditioning during spaceflight.

    • The design of ARED provides the user with the ability to perform resistive exercise on board the International Space Station (ISS). The ARED employs vacuum cylinders to provide a constant resistance, while flywheel assemblies provide a variable resistance. The variable resistance supplied by the flywheel assemblies is designed to mimic the inertial forces generated when lifting free weights on Earth.


  • The ARED is required to have an on-orbit service life of at least 15 years, with a total cycle life of 11.23 million cycles. Eighty percent of the cycles will be bar exercises performed using the lift bar assembly, and twenty percent of the cycles will be cable exercises performed using the cable assembly.

Credit : NASA

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