СРАВНИТЕЛЬНЫЙ АНАЛИЗ ХАРАКТЕРИСТИК ХОДЬБЫ В УСЛОВИЯХ КОСМИЧЕСКОГО ПОЛЕТА: АКТИВНЫЙ И ПАССИВНЫЙ РЕЖИМЫ РАБОТЫ БЕГУЩЕЙ ДОРОЖКИ

Abstract

Walking and running on treadmill BD-2 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. Purpose of the investigation is comparative analysis of biomechanical and electromyographic characteristics of walking in long-term space missions (SM) 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 4 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 soleus m. 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.