[The effect of 120 day anti-orthostatic hypokinesia on the status of the posture regulation systems].
The system of posture regulation was evaluated during 120-d head-down bedrest (-6 degrees). Functioning of the system was evaluated by the characteristics of corrective posture responses to pushes in the chest breaking the body equilibrium. Analyzed were parameters of amplitude and time of corrective responses, and strength and range of stimulus intensity. Results of the investigation showed that HD bedrest materially disturbs vertical stability and impairs effectiveness of the posture corrective mechanisms. Based on the data of this investigation and findings of previous efforts we can confidently distinguish two phases in development of disturbances in vertical stability during long-term HD bedrest associated with different leading mechanisms. On the first phase (15-30-d into the experiment), the principle posture problems are reduced tone of the anti-gravity musculature. On the second phase, particularly beginning on day 60, muscular atrophy processes become leading factors of postural disturbances. Apparently, these mechanisms, along with changed vestibular input, considerably impact vertical stability, especially after extended space mission.
Saenko
D G
DG
Saenko
I V
IV
Shestakov
M P
MP
Ivanov
A M
AM
Kozlovskaia
I B
IB
D001510:Bed Rest; D006801:Humans; D018476:Hypokinesia / Q000503:physiopathology*; D011187:Posture / Q000502:physiology*; D013997:Time Factors; D014893:Weightlessness