Реферат: A promising method of prevention of muscle atonia and atrophy occurring during prolonged unloading is electromyostimulation (EMS), which demonstrates high efficiency in clinical practice and training process. The aim of the study was to evaluate the effect of different modes of electromyostimulation on viscoelastic properties of muscles under conditions of support unloading. A total of 66 men in 5 groups participated in the study. To simulate the physiological effects of weightlessness, the model of Dry Immersion (DI) was used according to the standard procedure, the duration of exposure was 5-7 days. The myotonometry method was chosen to evaluate the viscoelastic properties, analyzing the muscle vibration frequency (Hz). For EMS-training, two stimulation modes were used: low-frequency EMS "LF-EMS" of 25Hz (1s stimulation, 2s relaxation; in 5-day DI - 240±5 min sessions, 7-day DI - 40±5 min.); high-frequency EMS "HF-EMS" with frequency of carrier oscillations - 2500Hz, frequency of the sinusoidal modulating voltage - 50Hz (10s stimulation, 50s relaxation, 20 min sessions). We evaluated the effectiveness of EMS-training in three shin muscles: tibialis anterior (TA), soleus (SO) and the lateral head of m. gastrocnemius (GL). Measurements were performed before the exposure (BDC), on the day of DI completion (R0) and on the 2nd day after DI (R+2). In both control groups on R0 frequency significantly decreased by 9% in TA and SO, whereas by R+2 the decrease was 7%. In the LF-EMS group a change was observed only in GL; thus, by R0 and R+2 the frequency significantly decreased by 10%, whereas in SO the frequency remained at baseline and in TA tended to increase. In the HF-EMS group there was an increasing tendency in the frequency in TA and SO to R0 by 13%, and no changes were observed in GL. After application of combined EMS a significant increase in frequency in SO and GL on R0 by 10% was observed, whereas in TA a significant decrease by 9% was observed, returning to baseline by R+2. The results of our study showed that daily use of EMS-training can help to preserve the viscoelastic properties of muscles during several days of support unloading. The optimal EMS-mode depends on the type of stimulated muscles: for postural muscles with a predominant MHC-I content, LF-EMS has the greatest positive effect, whereas for muscles with a high MHC-II content, HF-EMS would be more effective. The decreased frequency in TA in the combined EMS group may be due to the reduced HF-EMS training time during combined EMS (from 240 to 45 minutes), so LF-EMS stimulation was insufficient to train the entire TA muscle. The decrease in viscoelastic properties in the GL during the period of LF-EMS may be due to approximately equal amounts of MHC-I and MHC-II in the GL. This is supported by the positive effect of combined EMS in a similar experiment. The work was performed within the framework of the program of applied research of the IBMP RAS, carried out in the interests of medicine and public health (FMFR-2025-0001).

Библиографическая ссылка: Ponomarev I. , Saveko A. , Bekreneva M. , Abu Sheli N. , Shigueva T. , Rukavishnikov I. , Koryak Y. , Tomilovskaya E.
ELECTROMYOSTIMULATION AS A METHOD OF ATONIA PREVENTION UNDER DRY IMMERSION OF DIFFERENT DURATION
44 Annual the International Society of Gravitational Physiology Meeting (ISGP), Sapporo, 2025 18-23 May 2025