Spectral analysis of the human body sway during standing on firm and compliant surfaces under different visual conditions

Psychophysiological Indicators of Postural Control. Contribution of the Russian Scientific School. Part I

“…The weighty contribution of the Russian scientific school was made at the very beginning of postural control studies for the objectification of the measurements of postural stability. According to the recommendations of the International Consensus on postural control measurements [ 27 ] established based on “Research Methods to Evaluate Standing Stability” developed in 1952 by Russian scientists [ 28 ], the efficiency of the balance maintenance system is assessed by measuring oscillations in the foot plantar center of pressure (COP) relative to the center of gravity (CG) [ 29 ]. These variations reflect the movements of body segments or joints, muscle activity, the movements associated with respiration [ 30 ], and the work of the cardiovascular system [ 31 ].…”

“…Later, Yu.S. Levik et al [ 15 ] showed that the relatively high-frequency COP oscillations did not affect the value of CG variations [ 15 , 29 ]. COP oscillations with the frequencies below and above 1 Hz demonstrate the opposite effect on the reflexes and EMG activity of m. soleus while standing [ 34 ].…”

“…The evidence of the coexistence of the two systems of balance maintenance was provided by the studies of zero gravity at the Russian School of Aerospace Medicine [ 29 ], in the differential diagnostics of vestibular disorders [ 36 ], as well as by using the theoretical model of B.W. Dijkstra et al [ 37 ].…”

“…It has been shown that the ability to maintain balance persists during the short-term absence of gravity (zero gravity);. However, the conservative (tonic) system of balance maintenance is immediately impaired, the voluntary postural control takes effect [ 29 ]. This fact indicates two different types of postural control effective on different time scales, which is evidence of the weighty contribution of the cognitive component to postural control [ 38 ].…”

“…This fact indicates two different types of postural control effective on different time scales, which is evidence of the weighty contribution of the cognitive component to postural control [ 38 ]. Later, statistical analysis revealed three types of COP oscillation dynamics correlating with psychophysiological indices [ 29 , 38 ]. For example, the peak in the range of 3–5 Hz is a signal for the presence of Parkinson’s tremor [ 39 ].…”