Preventive Efficiency of Resistive Exercises for the Bone System of Cosmonauts in Repeated Long-Duration Space Missions

The purpose of this investigation was to estimate the efficiency of training with expanders and power trainers against changes in bone mineral density (BMD) during long-duration space missions. The same group of cosmonauts was tested in two different missions aboard the International Space Station. Resistive exercises using expanders and training equipment were done every other day as was recommended by Russian coaches. Settings of the treadmill and bicycle ergometer programs did not differ much in the missions. Preventive efficiency of resistive exercises was evaluated by the results of pre- and post-mission densitometry (Hologic Delphy) of the lumbar vertebrae ( L 1 – L 4 ), femoral neck, and greater trochanter. It was shown that the use of power trainers is explicitly more effective in BMD loss prevention than expanders. In light of prospective exploration missions, it is an important result that suggests that mineral density in the lower part of the skeleton could be kept under control despite prolonged exposure to microgravity through daily resistive exercises using power trainers.