Alina Saveko

Objective: To test whether inpatient electrical muscle stimulation (EMS) using Russian current (5 kHz carrier, 50 Hz modulation; 4 s ON/6 s OFF) improves mobility and balance in elderly people with chronic cerebral ischaemia. Design: Prospective single-centre controlled observational pilot, embedded in routine inpatient rehabilitation; no concealed randomisation (EMS + standard care; sham EMS + standard care; standard care only (control)). Methods: A single-centre controlled observational study with three groups was conducted (EMS n = 27, control n = 10, sham n = 7) with 3–9 sessions over 2 weeks (20 min; quadriceps and calves). Pre/Post Outcomes: Tinetti (balance/gait), Rivermead Mobility Index, Timed Up and Go (TUG), ankle extensor maximal voluntary force (MVF), stabilography (statokinesiogram path length (L), mean velocity of COP (V), sway area (S), and myotonometry; ANOVA, α = 0.05). Ethics approval and informed consent were obtained. Between-group differences in change scores were evaluated descriptively, and no formal hypothesis-testing was planned. Results: EMS showed significant gains versus control/sham—higher Tinetti total and Rivermead scores, faster TUG, higher MVF, and improved stabilography in the eyes-closed condition (reduced L, V, and S), with good tolerability and no serious adverse events (SAEs). Conclusions: Short-course Russian-current EMS is feasible and associated with clinically meaningful improvements in balance, gait, and strength in elderly patients with chronic cerebral ischaemia; however, larger randomised trials are warranted.

During interplanetary expeditions, the crew must adapt not only to gravity transitions but also to long-term stay in a limited space of a space station. In such conditions, it develops a significant decrease in motor activity and the formation of a special stereotype of movements in these conditions. Within further planning of ground-based and real interplanetary missions, it is appropriate to assess the impact of these factors on the crew’s functional condition, including when modeling lunar gravity using suspension and virtual reality (VR) technologies. The purpose was to determine the functional capabilities of five members of the international crew of the 240-day SIRIUS-21 isolation experiment when performing an extravehicular activity (EVA) after 4 and 6 months of isolation in the hermetic facility. During EVA, the crew performed basic motor tasks using VR on an uneven surface: positional tests, voluntary and tandem walking, walking when avoiding and stepping over obstacles, and verticalization from lying and standing on one knee positions. The EVA scenario included tasks of controlling the rover with the arms deweighted, as well as movement in a VR environment on a sliding surface with the body deweighted on the moon. In this study, we presented results of qualitative and quantitative analysis of video recording data and qualitative analysis of the electromyographic activity of the muscles of the lower extremities. The results indicate a sufficient level of functional performance of SIRIUS-21 crew members, all the EVA tasks were completed by the crew in full, while no cases of significant loss of balance and signs of pronounced locomotor and vestibular disorders were registered. At the same time, this paper highlights some features of the crew’s EVA performance, the effects of sensorimotor training on some tasks with repeated EVA experience, the most common errors, and difficulties in performing the tasks of the EVA scenario.

Walking and running on a BD-2 treadmill in the active and passive modes are the core of the Russian countermeasure system on board the International Space Station (ISS). In the active mode, the belt moves owing to the electric drive and in the passive mode the cosmonaut makes the belt move with the help of leg force. One of the primary goals of this investigation is better understanding of the physiological aspects of these training sessions. The purpose of the investigation is comparative analysis of biomechanical and electromyographic characteristics of walking in long-term space missions (SMs) using the BD-2 active and passive modes. The investigation involved 22 cosmonauts at the age of 45.7 ± 4.7 yrs. in the course of 115- to 340-day missions to the ISS. The cosmonauts performed the locomotion test monthly (no less than four times). Two sessions of the investigation were conducted prior to launch and two sessions on days 8 and 12 in the period of post-flight recovery. Protocol of the locomotion test (3-min walking) was performed twice, i.e., in the active and passive modes. Walking biomechanics was assessed using the podogram recorded with pressure cells built in sensing insoles. Electromyographic activity of the next four muscles was measured simultaneously: anterior tibial muscle, soleus, lateral gastrocnemius, and quadriceps muscle of the thigh. Results demonstrate greater values of support reactions and electromyographic activity of the gravity-dependent m. soleus in the passive mode as compared to the active mode in all test sessions. This can be, probably, explained by a tighter foot contact with the treadmill belt in the passive mode and, as a consequence, increased intensity of support afferentation signals. It is notable that this difference grows in microgravity.

The effectiveness of the support stimulation of the mechanoreceptors of the feet has been first shown in space medicine. In space flight during support withdrawal with non-use of postural muscle, this method is a countermeasure against sensorimotor disorders. Later, it was applied in clinical practice as treatment of motor disorders after stroke, in Parkinson’s disease, infantile cerebral palsy, neuropathies, and many others. The impact of such stimulation on motor control is due to spinal and supraspinal mechanisms, which are activated by creating an additional support afferent input through the plantar surface. Many studies confirmed the positive effect of support stimulation on motor control, but the protocols of such stimulation remain the subject of active discussion. This review includes (1) the features of sensitivity of the foot sole cutaneous afferents to the support mechanical stimuli, (2) data on spinal and supraspinal responses of the nervous system to support stimulation, and (3) the results of applying this approach in neurological practice via various techniques. Summarizing this information, the authors highlight the most promising ways and types of medical devices for foot support stimulation in neurology.

During space flight, the changes in the functions of the upper limbs can affect the quality of operator activity. At the same time, there are very few data on this topic, because most of the research is focused on the structure and functions of the lower extremities. The aim was to study the characteristics of the grip force control during the decrease of the support and proprioceptive sensory signals in the conditions of the ground-based model of the effects of space flight, Dry Immersion (DI). The duration of DI exposure was 21 days. 10 male volunteers performed tests using a hand dynamometer for maximal voluntary contraction, the maintenance of the reference force, the reproduction of this force from memory, and the grip force gradation test. The subjects performed this series of tests before exposure to DI, then on days 1, 3, 5, 10, 15, and 20 of DI, and days 1 and 3 of the recovery period. The results show that DI exposure led to an increase in proprioceptive sensitivity in the tasks without visual feedback when with open eyes from day 5 of DI the subjects made more mistakes in the reproduction of the reference force using the dominant hand. The sensory processing/modulation disorder under DI factors may cause this phenomenon.

Corrigendum: Impact of different ground-based microgravity models on human sensorimotor system

Corrigendum: Editorial: Rising stars in environmental, aviation and space physiology: 2022