[Tolerance of functional and exercise tests during 1-year antiorthostatic hypokinesia]. / Perenosimos't obsleduemymi funktsiona'lno-nagruzochnykh prob v usloviiakh godovoi antiortostaticheskoi gipokinezii.

During 370 days 9 healthy young volunteers were exposed to antiorthostatic hypokinesia. Group A consisting of 4 subjects performed exercises similar to those regularly made by Mir crewmembers and Group B consisting of 5 subjects did not exercise for 120 days and then performed experimental exercise regimens. It was demonstrated that the health status of men long exposed to head-down tilting can be controlled with the aid of various countermeasures. As a result of the exposure, orthostatic and exercise tolerance diminished. In view of the fact that the changes observed were more pronounced in the Group B subjects, it can be concluded that the countermeasures used were more effective in Group A subjects.

[Effect of a 30-day period of hypokinesia on various physiologic and biochemical indicators during maximal physical load]. / Vliianie 30-sutochnoi gipokinezii na nekotorye fiziologicheskie i biokhimicheskie pokazateli pri maksimal'noi fizicheskoi nagruzke.

Exercise tolerance of test subjects who remained bed rested (Group A) and who exercised while being supine (Group B) was measured before and after 30-day head-down tilt (-8 degrees). Special attention was given to the parameters that characterize energy supply of working muscles. The data obtained after 30-day bed rest did not reveal any changes in the Group B subjects and showed the following changes in the Group A subjects: maximum oxygen consumption decreased by 10.1% (p less than 0.05), the time within which the anaerobic metabolism threshold was attained decreased by 17.2% (p less than 0.05), and lactate concentration at the workload end decreased by 24.7%, while the pyruvate concentration and the lactate/pyruvate ratio remained unchanged. The results indicate that prolonged aerobic workload after 30-day bed rest seems to be limited by functional changes in oxygen transport rather than by the factors associated with changes in energy supply of working muscles.

[Functional status of the human cardiorespiratory system after 30 hours' antiorthostatic hypokinesia]. / Funktsional'noe sostoianie kardiorespiratornoi sistemy cheloveka posle 30-sutochnoi antiortostaticheskoi gipokinezii.

Before and after 30-day head-down tilt (-8 degrees) the cardiorespiratory function of six healthy volunteers was assessed using an exercise test (aerobic workload on the treadmill that grew to the maximal level). After hypokinesia the maximal oxygen consumption decreased by 9.9% and total oxygen debt by 23% (P less than 0.05). The bioelectric activity of the heart showed a decrease of the TA wave by 34% and the TD wave by 30% (P less than 0.05). These changes give evidence that the functional capacity of the cardiorespiratory system declined and as a consequence the ability of the test subjects to perform sustained physical work of aerobic character also decreased.

[Effect of motor activity on aerobic performance of healthy subjects]. / Vliianie urovnia dvigatel'noi aktivnosti na aérobnuiu proizvoditel'nost' zdorovogo cheloveka.

Bicycle ergometry studies in which 120 healthy male volunteers, aged 20--40, look part, showed that aerobic performance depended on their normal motor activity. In the test subjects, leading an active mode of life, maximum oxygen uptake and general work capacity were significantly higher than in those leading a sedentary mode of life. The data obtained give evidence that the people with diminished muscle activity should be recommended to do regular exercises in order to maintain aerobic performance.

[Some physiological effects caused by 30 days of bed rest in different body positions]. / Nekotorye fiziologicheskie effekty, obuslovlennye 30-sutochnym postel'nym rezhimom s razlichnym polozheniem tela.

Eighteen male test subjects were exposed to a 30-day bed rest with the foot end of the bed tilted at +6 degrees, -2 degrees or -6 degrees. Control subjects were allowed a normal mode of life during the same period of time. Hypokinesia was shown to play the leading role in the genesis of most changes, since control subjects displayed no changes. It was concluded that head-down tilt simulated changes occurring during adaptation to weightlessness better than recumbency or head-up tilt.