This study aimed to test the hypothesis that the postactivation effect (PAE, involuntary normal muscle tone) is modified by dopaminergic mechanisms. The PAE was tested with surface electromyography (sEMG) in the "off medication" phase in participants with Parkinson's disease (PDoff) and in the "on medication" state in participants with schizophrenia (SZon), which modeled hypodopaminegic conditions, and in participants with PD "on medication" (PDon) and in participants with SZ "off medication" (SZoff) state which modeled the hyperdopaminergic conditions. Healthy age-matched participants constituted the control group (HC, n = 11). In hyperdopaminergic models, PAE was triggered in 71.3% of participants in SZoff and in 35.7% in PDon conditions. In the hypodopaminergic models, PAE was triggered in 12% in SZon and in 21.4% in PDoff conditions. In the HC group, PAE was present in 91% of participants. In the HC and PD groups, the mean frequency and correlation dimension of sEMG at PAE was higher than that during voluntary isometric contraction. In conclusion, in hypodopaminergic models, PAE triggering was inhibited. The manifestations and EMG characteristics of PAE in people with PD or SZ may indicate dopaminergic dysfunction.

The primary aim of the study was to assess cerebral circulation in healthy young subjects during an ultra-short (45 min) session of ground-based microgravity modeled by "dry" immersion (DI), with the help of a multifunctional Laser Doppler Flowmetry (LDF) analyzer. In addition, we tested a hypothesis that cerebral temperature would grow during a DI session. The supraorbital area of the forehead and forearm area were tested before, within, and after a DI session. Average perfusion, five oscillation ranges of the LDF spectrum, and brain temperature were assessed. Within a DI session, in the supraorbital area most of LDF parameters remained unchanged except for a 30% increase in respiratory associated (venular) rhythm. The temperature of the supraorbital area increased by up to 38.5 °C within the DI session. In the forearm area, the average value of perfusion and its nutritive component increased, presumably due to thermoregulation. In conclusion, the results suggest that a 45 min DI session does not exert a substantial effect on cerebral blood perfusion and systemic hemodynamics in young healthy subjects. Moderate signs of venous stasis were observed, and brain temperature increased during a DI session. These findings must be thoroughly validated in future studies because elevated brain temperature during a DI session can contribute to some reactions to DI.

The Quality of Life (QoL), especially of frail and older people, depends on the ability of a person to tolerate stresses and its negative consequences. The toleration is related to the human resilience, reflecting the three basic human functions: cognitive (the thinking process), motor (the movement activity), and autonomous (the internal body processes). The cognitive resilience is acknowledged as one of the main components of human resilience. The cognitive resilience is tightly coupled with the motor resilience. Various motor-cognitive tests are known to assess the reactivity in a custom way and with specialized medical equipment. In this paper, we introduce our concept model of the mobile Health (mHealth) sensorics for digital assistance of the human resilience during person's daily activity. In reactivity testing, a smartphone becomes a core element, replacing specialized medical equipment and transforming to a daily automatic instrument of human motor-cognitive sensorics. The collected measurements provide the base to monitor person's mental condition.

There is a gap in the current knowledge on the immediate mechanisms of cardiovascular regulation in human subjects within short-term exposure to modeled microgravity using “dry” immersion. Aim. The purpose of the study was to evaluate cardiovascular responses in young healthy subjects during a 45 min session with the help of linear and nonlinear heart rate variability and hemodynamics parameters. The research voluntarily enrolled 33 subjects (18 men, 15 women) aged 19–23 years old. Results. The study showed that systolic and diastolic blood pressure was quite stable, some time-domain parameters of heart rate variability (SDNN, RMSSD, pNN50, etc.) and the frequency-domain (TP, HF, LF, but not VLF) have significantly increased within a 45 min “dry” immersion session. Of the non-linear parameters of heart rate variability, only ApEn significantly decreased during the “dry” immersion session. Conclusion. Our results suggest that a short-term 45 min DI session provokes in young healthy subjects neurogenic autonomic reaction based on the baroreceptor reflex. This provides stable hemodynamics in these subjects along the “dry” immersion session.

In this research report, we present data on a “non-drug” PD subject who completed five repeated courses of (a total of 26 hours of DI) over 44 months combined with self-initiated physical exercise. The program of five repeated courses of DI has retarded the progression of some PD symptoms for 22 months or more, but then exponential growth of UPDRS-III scores did take place. The initial positive effect of the DI sessions have, at least in part, due to the placebo effect of DI. On the other hand, UPDRS-II scores remained stable, and the sense of smell persisted. Due to the DI intervention, the subject began to engage in daily physical activity, which presumably exerted noticeable “ountermeasure” effect. Overall, repeated courses of short DI sessions cannot seriously retard the progression of PD, although its initial positive effect could probably help motivating to start physical exercising counter PD disorders.

Parkinson's disease (PD) is increasingly being studied using science-intensive methods due to economic, medical, rehabilitation and social reasons. Wearable sensors and Internet of Things-enabled technologies look promising for monitoring motor activity and gait in PD patients. In this study, we sought to evaluate gait characteristics by analyzing the accelerometer signal received from a smartphone attached to the head during an extended TUG test, before and after single and repeated sessions of terrestrial microgravity modeled with the condition of "dry" immersion (DI) in five subjects with PD. The accelerometer signal from IMU during walking phases of the TUG test allowed for the recognition and characterization of up to 35 steps. In some patients with PD, unusually long steps have been identified, which could potentially have diagnostic value. It was found that after one DI session, stepping did not change, though in one subject it significantly improved (cadence, heel strike and step length). After a course of DI sessions, some characteristics of the TUG test improved significantly. In conclusion, the use of accelerometer signals received from a smartphone IMU looks promising for the creation of an IoT-enabled system to monitor gait in subjects with PD.

The existing literature suggests that temperature and gravity may have much in common as regulators of physiological functions. Cold, according to the existing literature, shares with gravity common effects on the neuromuscular system, while heat produces effects similar to those of microgravity. In addition, there are studies evidencing unidirectional modification of the motor system to heat and hypoxia. Such agonistic relationship in a triad of “microgravity, heat, and hypoxia” and in a pair of “cold and gravity” in their effect on the neuromuscular system may have evolutionary origins. To address this problem, ten years ago, we came up with a concept with the working name Baby Astronaut hypothesis, which posed that “Synergetic adaptation of the motor system to different environments comes from their ontogenetic synchronicity.” More specifically, the synchronicity of microgravity (actually, the “wet immersion” model of microgravity), higher temperature, and hypoxia are the characteristics of the intrauterine environment of the fetus. After childbirth, this group of factors is rapidly replaced by the “extrauterine,” routine environment characterized by Earth gravity (1 G), normoxia, and lower ambient temperature. The physiological effect of cold and gravity on the motor system may well be additive (synergistic). We earlier estimated a “gravity-substitution” potential of cold-induced activity and adaptation to cold as 15–20% of G, which needs further validation and correction. In this study, we sought to critically analyze the interaction of temperature and gravity, based on the concept of Baby Astronaut, using data from the new academic literature. We have come to the conclusion that the concept of Baby Astronaut can be regarded as valid only for species such as a rat (immature, altricial species), but not for a human fetus. Several confirmatory experiments were suggested to verify (or falsify) the concept, which would allow us to consider it as empirical. In addition, the interaction of temperature and gravity may be of practical interest in the fields of neurorehabilitation and habilitation in childhood for constructing a physical environment, which would help strengthen or weaken muscle tone in specific muscles.

The quality of life depends on the human resilience to stresses and other negative impacts from the environment and society. We assume that the human resilience can be effectively supported by motor activity. The problem is that people reduce the motor activity (the human mobility) although they are potentially able to move (the human motility). In this paper, we consider human motor activity sensorics and study the concept of mobile Health (mHealth) system to digitally support the mobility of a person during her/his daily life. The sensorics is based on inertial sensors of a smartphone that accompanies the person. The smartphone evaluates various motor tests for the human activity. The collected statistics provide an interesting picture to motivate the person to more activity. We introduce the concept model that interrelates human resilience and motor activity. We discuss possible digital support of human resilience based on testing the human activity. In sum, this study contributes our concept of smartphone-based mHealth system that digitally supports the motor activity of a person in daily life subject to increase the human resilience.

Several studies have shown that "dry" immersion appears as a promising method of rehabilitation for Parkinson's disease. Still, little is known about the cardiovascular reaction in "dry" immersion (DI), especially in Parkinson's disease (PD). Therefore, this study was aimed to evaluate the effect of repeated 45-min DI sessions on autonomic function in subjects with PD. The study group consisted of 20 subjects with PD [13 men, seven women, aged 51-66 years old, Hoehn & Yahr (H&Y) staged 1-3] were enrolled in the study according to inclusion and non-inclusion criteria. The DI program was comprised of seven 45-min DI sessions, applied within 25-30 days. Blood pressure (BP), heart rate (HR), and electrocardiogram (ECG) in the standard lead II were recorded at 1st, 4th, and 7th DI, before, on the 15, 30, and 40th min of DI session. Autonomic function was assessed with analysis of heart rate variability (HRV) using Kubios Standard version 2 software. Linear (time- and frequency-domain) and non-linear (correlation dimension, entropies, DFA1 and DFA2, percent of determinism, and recurrence) were computed. At baseline condition, time- and frequency-domain HRV parameters showed low variability of HR, which indicates reduced autonomic neurogenic control of HR. Throughout the DI session, systolic and diastolic BP has decreased by 5-7 mm Hg (p < 0.001), and time- and frequency-domain parameters of HRV have significantly increased, what can be regarded as compensatory mechanisms of hemodynamics during DI. The structure of the regulatory input to the heart seen by HRV was characterized by low complexity and reduced autonomic neurogenic control of HR. Across the program of DI sessions, the hypotensive effect was documented, but no notable modification of the HRV-parameters was found. The absence of long-term modification of the studied parameters can be attributed both to deconditioning environmental effect of DI and limited adaptation of the organism due to neurodegeneration in PD. That should be taken into consideration when planning rehabilitation measures in subjects of older age and chronic somatic diseases with modeled microgravity.

The purpose of this study was to evaluate technical reliability of a commercially available treadmill to induce slip displacement, which is sufficient to provoke postural reactivity in subjects with Parkinson's disease (PD). These subjects underwent the program of ground-based microgravity modeled with “dry” immersion (DI). Additionally, in the same study group we assessed the function of postural transition. Both postural reactivity and transition were traced with motion videocapture technique. We found that at 1 km/hour treadmill did produce acceleration and, hence, heel strike, detectable for motion videocapture. Therefore, from the methodological point of view the study looks promising. However, this acceleration proved lesser than it is usually applied in suchlike studies. In part, this explains for the lack of significant effect of the DI program on the characteristics of postural compensation reactions in subjects with PD. Alternatively, the result could be explained by weak effect of DI on the studied postural functions. For future studies, we regard that inertial measuring units (IMU) and stronger acceleration would better fit the task to study postural reactions in subjects with PD.

The study hypothesis held that in subjects with Parkinson’s disease (PD), the reaction time (RT) tests of the higher cognition demand would have more readily improved under the program of analog microgravity (μG) modeled with “dry” immersion (DI). To test this hypothesis, 10 subjects with PD have passed through a program of seven DI sessions (each 45 min long) within 25–30 days, with overall μG dose 5 1/4 h. Five patients were enrolled as controls, without DI (noDI group). Simple RT (SRT), disjunctive RT (DRT), and choice RT (CRT) were assessed in four study points: before the DI program (preDI), 1 day after the DI program (postDI), 2 weeks after the DI program (DI2w), and 2 months after the DI program (DI2m). The motor time (MT) was assessed with the tapping test (TT). Additionally, signal detection time (SDT) and central processing time (CPT) were extracted from the data. Before the program of DI, the RT tests are in accordance with their cognition load: SRT (284 ± 37 ms), DRT (338 ± 38 ms), and CRT (540 ± 156 ms). In accordance with the hypothesis, CRT and DRT have improved under DI by, respectively, 20 and 8% at the study point “DI2w,” whereas SRT, SDT, and MT did not change (<5% in the preDI point, p > 0.05). Thus, the program of DI provoked RT improvement specifically in the cognitively loaded tasks, in a “dose of cognition-reaction” manner. The accuracy of reaction has changed in none of the RT tests. The neurophysiologic, hormonal/neuroendocrine, behavioral, neural plasticity, and acclimation mechanisms may have contributed to such a result.

This study was aimed at evaluation of autonomic dysfunction in patients with multiple sclerosis (MS) by means of time- and frequency-domain parameters of heart rate variability (HRV) and conventional cardiovascular tests (deep breathing (DB) and active orthostatic test (AOT)). The study group enrolled 32 patients with the relapsing-remitting MS (17 m, 15 f, aged 29 ± 4.9 years, disease duration 4.2 ± 2.7 years, EDSS scores less than 3.0 and 26 subjects in good health (HC, 15 m, 11 f, aged 30.1 ± 2.7 years). In the MS group, at rest the variability of heart rate was decreased in comparison to the HC group seen by time- (SDNN, RMSSD, pNN50, CV, p < 0.01) and frequency-domain (TP, HF, LF, p < 0.05) parameters, what was indicative of the general decrease of the autonomic neurogenic control of the heart rate, both sympathetic and parasympathetic. The functional tests (DB and AOT) showed reduced cardiovascular reactivity in the MS group. Additionally, the cardio-respiratory synchronization was impaired in the MS group at rest and DB. The severity of HRV deficit in the MS group correlated with the activity of MS. In conclusion, the comprehensive assessment of time- and frequency-domain HRV parameters studied with functional tests provides better insight to understanding autonomic dysfunction in subjects with relapsing-remitting MS.

Tobacco smoking, as a harmful individual habit, aggravates the negative environmental effects on health in people living in the northern regions of Russia, by increasing the incidence of diseases of the cardiovascular and respiratory systems, and oncological diseases. This study was aimed at elucidating the vasomotor reactions on local cooling in young people with nicotine addiction. Materials and methods. Twenty four practically healthy people (13 m, 11 f) aged 18-27 years were enrolled to the study. Of these, 16 subjects with initial stage of nicotine addiction formed the study group, and 8 non-smoking subjects served as a reference group. The degree of nicotine addiction was assessed with the Fagerstrom test and the smoking index. The local cold test (LCT) was used to study vasomotor reactions. The autonomous regulation was estimated by analyzing the time- and frequency-domain characteristics of heart rate variability (HRV). Results. In the group with nicotine addiction, increased cold-induced vasoconstriction was revealed from the dynamics of the hand skin temperature during LCT. Also, this group mwas characterized by decreased vagotonia seen as lower values of time- (SDNN, RMSSD, pNN50 and CV) and frequency- domain (TP, HF and LF) parameters of HRV. The functional test with deep controlled breathing revealed in this group lower reactivity of neurogenic mechanisms of heart rate control. Among subjects with higher number of cigarette consumption, HRV changes which corresponded with adaptation disorders were more notable. Conclusion. Individuals with initial degree of nicotine addiction were characterized by the impaired reactivity of the central and peripheral parts of the circulatory system what means lower health capacity of the organism. Increased vascular reactivity during LCT, as well as the impaired adaptation seen with HRV analysis, could serve as early indicators of the systemic effects of tobacco smoking.

The aim of this study was to characterize the vertical spatial orientation of the body in patients with Parkinson’s disease (PD) and healthy young (HY) controls after a single and course action of simulated microgravity in the form of “dry” immersion (DI) using computer stabilometry. After a single 45-min DI session, the trajectory parameters of the common center of pressure (CCP) in PD (n = 9) and HY (n = 12) did not change (p > 0.05), although a slight tendency for them to decrease was noted. The course of seven DI sessions (each 45 min long, within 30 days) in PD patients (n = 17) did not affect the stabilometry parameters either. The effect of a single DI session did not become more significant by the end of the DI course. The use of Romberg’s test with closing the eyes did not exercise the influence of DI on the stabilometry parameters. At the same time, after the DI session in PD patients, the score on the UPDRS-III scale decreased by 33% (p < 0.05); muscle rigidity, by 37% (p < 0.05); tremor, by 27% (p < 0.05); akinesia, by 30% (p < 0.05). Thus, there is a discrepancy between the effect of DI on clinimetrically and instrumentally measured variables, which may be due to (1) insufficient complexity of the task, (2) unaccounted influence of DI on the stabilogram trajectory separately in the frontal and sagittal planes, and (3) unaccounted factor in the development of the stabilometric signal in time.

The purpose of this study was to evaluate reliability of basic parameters obtained with conventional stabilographic tests, and step characteristics recorded with motion videocapture, for fast robust assessment of the contribution of the vestibular system, vision, and proprioception to vertical stance and walking in healthy subjects. The contribution was computed as “weight coefficients” of each of the sensory input to the net motor outcome (the body balance at easy vertical stance and locomotion) at the conditions with deprivation of either vision (Romberg's test) or proprioception (“foot reaction” test), or both vision and proprioception. We found, that during easy vertical stance tested with stabilography, only the path length of the center of pressure presented relevant data. It allowed to estimate the contribution of the proprioception as cal. 0,5, while vision and the vestibular system both contributed roughly with 0,25. During walking, the vestibular system's contribution was 0,7 - 1,0 of the net share, while that of vision was negligible. These data generally correspond with the results obtained with more precise “science-intensive” methods. As such, conventional stabilography at various sensor-deprivation conditions could have had potential to assess, predict and prevent motor disorders.

This study was aimed at estimation of the effect of a course of seven short-term sessions of dry immersion (DI) on autonomic regulation in patients with parkinsonism. Seven patients with parkinsonism (five men and two women at the age of 51–66 years, with the severity of the disease of 1–3 on the H&Y scale) participated in the study. Analysis of time and frequency domains of heart rate variability (HRV) and blood pressure (BP) control were performed under the conditions of a baseline test, during deep controlled breathing and orthostatic test before the course of dry immersion, immediately after the course, and two weeks later. HRV analysis in patients with parkinsonism showed a significant decrease in the reactivity of the autonomic nervous system, determined by low values of HRV time-domain parameters ( SDNN , RMSSD , pNN50 , CV ), as well as the total power spectrum, LF and HF spectrum domains. A course of seven sessions of dry immersion caused a decrease in blood pressure, but did not exert a significant effect on HRV parameters at baseline test and during functional tests, which evidences the autonomic dysregulation in patients with parkinsonism. The peculiarities of autonomic reactivity in patients with parkinsonism requires the careful enroll of subjects when using dry immersion for rehabilitation and also monitoring of the cardiovascular function during this procedure.

The objective of this study was to characterize, using surface electromyography (EMG), the postactivation effect (PAE) arising in the deltoid muscles of healthy young subjects after a single 45-min procedure of “dry” immersion (DI) used as a model of microgravity. The working hypothesis was that PAE had to decrease as a consequence of exposure to DI. But it has been established against the initial hypothesis that the PAE in deltoid muscles increased nearly twofold, from 66 to 135 s, without any statistically significant effects on the EMG amplitude or mean frequency. The following factors were considered in the study as probable contributors to the results: (1) the factor associated with the biomechanical function of deltoid muscles and the related probability of a “sensory conflict” between the DI effect and the necessity to maintain the balance function, (2) the factor of DI application conditions, (3) the factor of complexity in the task (a vertical posture) for the induction of PAE, and (4) the factor related to the involvement of the internal body representation system in the PAE manifestation. The obtained data are intended for the use in further studies on the effect of microgravity analogs on the muscle tone and rigidity in patients with Parkinson’s disease and its rehabilitation potential.