Sensory Organization Of Postural Control After Long Term Space Flight Conference attendances
Language | Английский | ||
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Participant type | Устный | ||
URL | https://www.frontiersin.org/books/ISGP_Annual_Meeting_2023/12224 | ||
Conference |
42nd Annual the International Society of Gravitational Physiology Meeting 02-07 Jun 2023 , Антверпен |
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Abstract:
Introduction Postural stability deficit is an inevitable consequence of space flights (SF) of any duration (BLACK and PALOSKI 1998; Wood et al. 2015). In 1970 Nashner introduced a Computerized Dynamic Posturography (CDP), the development described in Black and Paloski, 1998. It is based on creating conditions when information from either visual, proprioceptive or vestibular inputs becomes unreliable or insufficient to determine the orientation of the body in relation to the gravitational vertical. Also, it has been shown that the hip strategy is engaged in complicated support surface conditions, whereas the ankle strategy is used in normal conditions (Horak and Nashner 1986). In this study we attempted to determine contributions of different sensory systems to postural control deficit in cosmonauts after long-term SF with the use of CDP and hip strategy involvement estimate. Methods The study involved 33 cosmonauts – crew members of expeditions to the ISS of 166-196 days duration. The studies were conducted twice before launch (L-30, L-60) and on the 3-4 (R+3), 7-8 (R+7) and 10-11 (R+10) days after landing. We used protocol from Wood et al., 2015, which include postural tests with sway referenced visual surround and support surface for disturbing visual and proprioceptive inputs and head tilting for disturbing the vestibular input. When processing the data, the scalar Equilibrium Score was calculated (Wood et al. 2015). Postural control may rely differently on proprioceptive or visual sensory inputs in different individuals. We divided subjects into two groups, according to the sensory modality, which was determined using the Romberg coefficient (RC) – a ratio of the values of the stabilographic parameters obtained when standing with eyes closed and eyes open (Fujita et al. 2005): the group of subjects with RC>1, i.e. with the leading visual modality ("visual" or V group), and the group with RC<1, i.e. with the leading proprioceptive modality, (“non-visual” or NV group). The cosmonauts were equipped with a system of infrared sensors (NDI OptoTrack, USA). Angles in the ankle, knee and hip joints were calculated. The average velocities of the angle fluctuations (VEL) and random mean square (RMS) of these fluctuations were analyzed. Results The majority of cosmonauts – 25 out of 33 – were included in V group. A separate examination of the V and NV groups revealed a better postural stability and a progressive recovery of post flight values in V group in the tests with eyes open (EO), Sway Referenced Visual Surround, as well as with eyes closed (EC), Sway Referenced Support Surface. In the test with EO and Fixed Support surface the significant changes in the VEL in the ankle joint were detected (from 0.13°/s to 0.17°/s, p = 0.014), while no changes were observed in the hip joint – the postural balance was provided by an ankle strategy. In the test with EO, Sway Referenced Support Surface on the 3rd day after landing significant changes in the RMS in the hip joint were detected (from 0.12° to 0.21°, p = 0.03), as well as a significant difference from hip joint RMS in the simplest test with EO and Fixed Support Surface, conducted in the same post-flight session (from 0.12° to 0.21°, p= 0.02). These changes suggest the recruitment of hip strategy for maintaining postural balance in the conditions of disturbed proprioceptive input. In the test with EC, Sway Referenced, Support Surface and head tilts significant changes in the VEL and RMS were found both in the ankle (from 1.23°/sto 2°/s, from 0.90° to 1.26°, p<0.001) and in the hip joints (from 0.47°/s to 0.86°/s, from 0.27° to 0.55°, p<0.001), which corresponds to 40% an increase in the median RMS value and a 44% increase in the 3rd quartile in the ankle joint, a 100% increase in the median RMS and a 135% increase in the 3rd quartile in the hip joint, which suggests an increase in the contribution of the hip strategy to balance maintenance (Kaminishi et al. 2021). Conclusion The changes in vestibular system activity play the leading role in reducing postural stability after a long-term space flight. The proprioceptive system is apparently the second in importance, and the visual system is of the least importance. Predominant sensory modality plays an important role in the efficacy of the postural control in sensory challenging conditions. Cosmonauts with a predominant reliance on the visual input demonstrate better stability than those who rely on non-visual sensory inputs. Long-term space flight leads to the change of postural strategy in the condition of unreliable proprioceptive input. The study was supported by the Russian Academy of Sciences (63.1)
Cite:
Nikita S.
, Vladimir K.
, Tomilovskaya E.
Sensory Organization Of Postural Control After Long Term Space Flight
42nd Annual the International Society of Gravitational Physiology Meeting 02-07 Jun 2023
Sensory Organization Of Postural Control After Long Term Space Flight
42nd Annual the International Society of Gravitational Physiology Meeting 02-07 Jun 2023