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The effect of excessive UV-radiation with 2-4, 5-6, or 7-8 minimal erythematous doses (MED) on man's health condition was investigated, when the irradiated surface area made 20% or 50% of the body surface area. Before and 1 or 3 days after exposure the following parameters were measured: skin state, skin perspiration, body temperature, fluid consumption, diuresis, ECG, PCG, occlusion plethysmography. The observations allowed the conclusion that 5-8 MEDs were threshold doses inducing early intoxication in response to local irradiation (20% of the body surface area) and upper body irradiation (50% of the body surface area). Irradiation with 7-8 MEDs caused noticeable intoxication: fever, headache, increased body temperature (37 degrees C and over), inhibited perspiration, fluid retention, and altered cardiac function.

The purpose of the present investigation was to study the aftereffect of UV-B-irradiation applied during 10 or 20 sessions. The biological effect and aftereffect duration of UV-B-irradiation of the upper body of 9 healthy volunteers (residents of the city of Moscow and its suburbs) were evaluated in autumn and winter. During UV-irradiation in the range 220-280, 280-320, or 320-400 nm the flux density was 0.035, 1.75, or 0.65 W/m2, respectively. Group 1 subjects (5 men) were exposed to UV-B-irradiation 10 times (once with 0.5, 0.6, 0.75, 0.9, 1.1, 1.35, 1.65 MED and three times with 2.0 MED) and Group 2 subjects (4 men) were exposed to UV-B-irradiation 20 times (twice with 0.5, 0.75, 1.0, 1.25, 1.5, 1.75 MED and eight times with 2 MED). The sessions were arranged every other day. The exposure produced a beneficial effect on the human body: skin sensitivity decreased, resistance of skin capillaries increased, Ca metabolism normalized, blood 25 (OH) D grew. The trend of responses was similar after 10 and 20 sessions; however, 20 sessions caused a longer-term aftereffect. In relation to space programs, it is concluded that UV-irradiation can be applied on the ground before short-term flights (less than 4 months) and in space during longer-term flights (greater than 4 months).

Three experimental series, in which 20 test subjects took part, were carried out to investigate the effect of super-erythemic doses of ultraviolet irradiation on metabolic parameters. It was found that UV irradiation of 12-15% of the skin area led not only to skin changes but also to functional changes in certain organs and systems, which was indicated by variations of metabolic parameters.

Healthy test subjects exposed to a 45-day head-down tilting (- 6.5 degrees) showed a decline of the tone and strength of certain muscle groups, a decrease of leg circumference, a deterioration of the walking pattern, and a reduction of exercise tolerance (provocative tests with bicycle ergometry pedaling at a moderate and maximum rate). Electrostimulation of muscles applied by the Tonus-2 equipment for 30 min twice a day, 6 days a week helped to reduce the level of hypokinesia-induced disorders.

The purpose of this study was to investigate biological effects of various regimens of ultraviolet irradiation in order to prevent UV insufficiency in men long kept in an enclosure. The subjects were kept for 60 days under artificial illumination in a Moscow laboratory in winter time. Two different regimens of UV irradiation were used and compared: 20 exposures at a dose of 0.75 MED and 20 exposures at incremental doses from 0.5 to 2 or 3 MED. Before and after 10 and 20 exposures (with medium-range radiation being predominant) the skin state, vitamin and mineral metabolism, and cytotoxicity of natural killers were investigated. The experimental observations allowed the conclusion that prophylaxis of UV insufficiency in men long kept in an enclosure can best be provided by UV irradiation at an incremental dose up to 2 MED. During this exposure skin sensitivity to UV radiation decreased, the content of vitamins D, A, E and that of Ca, P, Cu grew, and cytotoxicity of natural killers lightly increased. UV irradiation at a dose of 0.75 MED proved inadequate and that at a dose of 3 MED induced signs of excessive irradiation.

During a prolonged exposure to an altitude chamber (37-120 days) man's motor activity decreases 3- or 4-fold: from 15-19 thous. to 2-4 thous. steps per day. During a prolonged restraint in a chair in the position of "an average physiological rest" the number of movements falls to 5-7 per hour. The change of motor activity during hypodynamics and recovery follows three stages: an acute change, a slow change, and a stage of stabilization at a new level. It has been shown that the people who find themselves in an environment limiting their physical activity do not have the need for an additional workload.

Studies have been carried out 18-30 days before the flight and on the second day after landing. The recovery kinetics of cosmonauts who completed the 18-day space flight was followed for 30 days after their return. Muscle tone, indices of muscle strength and parameters of the functions of the extremities were examined, and the ability to maintain vertical posture was studied (stabilography). Flights of short duration did not cause any serious disturbances in the neuromuscular system. Together with this fact, the analysis of the results revealed a certain regularity in the physiological effects as reflected by a decrease in the strength of the torso extensors and the muscle tone of the lower extremities, The tone and strength of the arms altered insignificantly, and the alterations were not an indication of muscular atrophy. Stabilographic studies showed a decrement in the stability of the vertical posture of the cosmonauts. The above alterations were particularly pronounced in the crew members of Soyuz 9. As distinct from the previous flights of the Soyuz spaceships the crew members of Soyuz 9 showed normality in the regulation of vertical posture only on the tenth day after the flight. One of the reasons for the above alterations in postural regulation may be the decrease in muscle tone noted repeatedly after both of the previous space flights and in experiments with simulation of separate effects of weightlessness. Another reason for the deterioration in postural regulation is probably the changes in interaction between the neutral analysers. A possible reason for the apparent defects in stability may be the disturbance of the interaction between various muscle groups, i.e. the disturbance in synergism which is required for the maintenance of vertical posture. Similar alterations were observed in people who had been subjected to bed rest for a long time. Readaptation to the ground environment appeared to proceed in stages. The comparative evaluation of post-flight findings showed that prolonged periods of flights up to 18 days resulted in more pronounced alterations in human sensomotor coordination.