[Bone examination by noninvasive methods during prolonged hypokinesia]

The effect of 120-day bed rest on skeletal bones of 15 volunteers was investigated by noninvasive methods, viz. gamma-photon absorption, ultrasonic and neutron-activation analysis. The test subjects were divided into 4 groups one of which served as control and three others used different countermeasures (drugs, exercise or drugs in combination with exercise). Calcium loss in skeletal bones was not more than 0.5% per month; calcium loss in leg tubular bones was 1 to 2% per month in 6 test subjects; calcium loss in heel bones was on the average 3-4% per month in the control, exercise and combination groups. No strict correlation between the negative balance of calcium and mineral content in leg compact bones and foot spongy bones was found. There was a correlation between changes in the mineral content of leg bones and ultrasound propagation along certain compartments of the tibial median surface. In terms of negative and positive trends leg and foot bones were in better condition in the drug group. The techniques used were assessed with respect to their diagnostic and prognostic value.