Electromyographic evaluation of countermeasures during the terrestrial simulation of interplanetary spaceflight in Mars500 project

A Meigal; E Fomina

doi:10.1016/j.pathophys.2015.10.001

Electromyographic evaluation of countermeasures during the terrestrial simulation of interplanetary spaceflight in Mars500 project

Pathophysiology. 2016 Mar;23(1):11-8. doi: 10.1016/j.pathophys.2015.10.001. Epub 2015 Oct 24.

Authors

A Meigal¹, E Fomina²

Affiliations

¹ Institute of Advanced Biomedical Technologies, Petrozavodsk State University, Petrozavodsk, Russian Federation. Electronic address: meigal@petrsu.ru.
² State Scientific Center of Russian Federation Institute of Biomedical Problems of the Russian Academy of Sciences, Moscow, Russian Federation.

PMID: 26857518
DOI: 10.1016/j.pathophys.2015.10.001

Abstract

The efficiency of six countermeasures (CM) for muscle atrophy was compared over 520 days of confinement during the terrestrial simulation of round space flight to Mars using surface electromyography (sEMG). Three of CM were cyclic exercises (a motor-driven and leg-driven treadmill, cycle ergometer), resistive exercises (the multifunctional dynamometer for space-MDS, and expanders), and vibration platform. Each of CM was applied for each crew member (n=6) once over the experiment, for 70 days in a row, in prescribed order. sEMG was collected during the "force step test" in which the subject voluntarily produced pressure by lower limb, with minimal force increment. The mean frequency (MNF) and average amplitude of sEMG were analyzed. The MNF of sEMG decreased from 104.3±4.2 to 95.3±2.9Hz (P<0.05) in the soleus muscle after 70 days of exercising on the leg-driven treadmill and after 35 days-on vibration platform. It can be caused by earlier (10-250ms) recruitment of the soleus in respect with the medial gastronemius on the leg-driven treadmill, while on the motor-driven treadmill synergists activated synchronously. In other lower leg muscles, MNF decreased from 180 to 200 to 165-180Hz after 70 days of resistive exercises on the MDS device. CM caused no effect on sEMG amplitude. In conclusion, (1) the leg-driven treadmill, the MDS and vibration platform significantly depressed MNF of sEMG of lower extremity muscles; (2) the leg-driven treadmill and vibration platform specifically affected the soleus muscle. Therefore, these CM can be recommended for a more extensive use on ISS board.

Keywords: Confinement; Countermeasures; Simulation experiment; Skeletal muscles; Space flight; Surface electromyography.