Repeated horizontal jumping is a feasible exercise countermeasure for microgravity

Objectives: Astronauts who spend prolonged time in microgravity on the International Space Station can experience a significant reduction in physical fitness. Jumping exercises represent a potential solution to this problem as the European Space Agency has demonstrated that the deconditioning effect of long-term bed-rest can be countered with around four minutes per day of jumping. The purpose of this study was to evaluate if repeated jumping is possible in microgravity and if the transmission of impact forces and vibration to the aircraft can be minimised. Methods: Five subjects performed repeated jumping on a custom jump sled both in microgravity during a parabolic flight campaign and in normal gravitational conditions. Forces expressed by the user and transmitted to the aircraft were quantified using a bespoke instrumentation system. Results: These results show, for the first time, that repeated horizontal jumping is possible in microgravity, and that force transmission can be minimised by using a custom supine jump sled. The peak effective ground reaction force experienced by the user was sensitive to both the style of jumping used and resistance employed. Conclusion: These results open the door to the next generation of exercise countermeasures for deep space exploration. In particular, we have qualified the High Frequency Impulse for Microgravity (HIFIm) exercise device to a Technology Readiness Level of 6 making it a leading candidate to replace the Advanced Resistive Exercise Device (ARED) which has been in service since 2009.