[Changes in bone tissue of women under condition of 120 days antiorthostatic hypokinesia]

The state of bone tissue has been studied in 8 women subjected to a 120-day HDT. Four test subjects (Group A) performed physical exercises during the experiment. Mineral content (MC) in bone tissue and mineral density of the bones (MD) were determined with the help of dichromatic x-ray bone densitometer HOLOGIC QDR--100/W. The velocity of propagation of ultrasound in the shin bone was also determined. It is found that the hypokinesia-associated losses of bone mass in the lower segments of the skeleton of women were insignificant. In the control group (Group B, non-exercising subjects), there markedly increased MC in the bones of the upper body and there were the slight signs of hypomineralization of the segments of the lower body as well as the significant (in 2 test subjects) decrease of MC in the pelvic bones in the recovery period to the level lower than at the beginning of the experiment. In group A, the increase of MC in the upper skeleton was expressed to a lesser degree. At the recovery period the all changes were practically neutralized and there were no signs of bone mass loss. The velocity of ultrasound by the Day 90 of the experiment had the marked tendency for a decrease in group A persisting up to the end of experiment while in the group B its changes were oppositely directed. Within 2 months after the experiment in the majority of women the tendency for recovery of the initial state both by the absolute values of ultrasound velocity and by the profile of curves of their distribution over the anterior surface of the shinbone was noted. The results are discussed in comparison with findings obtained in the experiments with long-term hypokinesia in men and in the space missions.