[Synergy]
The elucidation of the re-adaptation on the attitude control

RESEARCH OVERVIEW

• During long-duration spaceflight, skeletal muscles, such as the soleus, are known to atrophy and many crewmembers have difficulty walking just after return to the earth. There is much research related to the muscle atrophy of astronauts, however, the full mechanism of the muscle weakness during space flight is still unclear. Therefore, it is necessary to evaluate the re-adaptation during crewmembers' walk in a comprehensive and systematic fashion.
• The re-adaptation on the balance control after return from long term space flight is evaluated. The results of this experiment help with understanding the resolution of the mechanism related with re-adaptation to gravity during walking, just after return to earth.
• The advantage of our experiment is the whole evaluation from analyzing 3 terms (EMG, Blood flow, Shift of gravity center) during walking just after return. These results provide the basic information to better understand the training program or rehabilitation.

Many astronauts stay onboard the International Space Station (ISS) for a long period of time. Therefore, the evaluation of crewmember health conditions are very important. During long duration flights, skeletal muscles such as the soleus, are known to atrophy, and many crewmembers have difficulty walking just after return to earth. There is much research related to the muscle atrophy of astronauts, however, the full mechanism of the muscle weakness during space flight is still unclear. Therefore, the purpose of this experiment is to evaluate the re-adaptation on balance control after return from long duration space flight.

To achieve this purpose, the following three terms are investigated, (1) comparing the electromyogram (EMG) pattern on the antagonist muscle of the lower limbs, (2) the measurement of the blood flow volume on the leg, and (3) the measurement of the shift of gravity center during the balance control. The data collection is performed before flight, or after the return to earth, not inflight. The focus is on muscle atrophy, or the vestibular system, is because of the difficulty of walking just after the crewmember return to earth. On the other hand, the focus is on the co-contraction of the antagonist muscle, or the balance control by the vestibular system and the cerebellum. These results provide the basic information to better understand the training program or rehabilitation.

DESCRIPTION

Many astronauts stay in the International Space Station (ISS) for a long period of time. Therefore, the development of astronaut health care technologies is very important. Especially, an understanding of the effects of the space environment, such as microgravity and radiation, on the human body is important for developing countermeasures against the adverse effects experienced by astronauts who are in space for long periods of time. During long-term flights, the physiological effects on astronauts include muscle atrophy and bone calcium loss. Greenleaf et al. reported that astronauts lose their aerobic power and muscle strength and experience deterioration in mood and psychological state (J. Appl. Physiol. 67, 2191-2204, 1989). Specifically, during long-term flights, the antigravity skeletal muscle, such as soleus, is known to become atrophy and many astronauts have difficulty walking just after the return to the earth. There are many researchs related to the muscle atrophy of astronauts. However, the final mechanism of the muscle weakness during space flight is still unclear. Therefore, the purpose of this experiment is to elucidate the re-adaptation on the attitude control after return from long term space flight.

To achieve this purpose, we will investigate the following three terms, (1) the comparing the electromyogram (EMG) pattern on the antagonist muscle of hindlimb, (2) the measurement of the blood flow volume on the leg, (3) the measurement of the shift of gravity center during the attitude control. We will perform these data collection only before going to space or after the return to the earth, not in-flight. It has been focused on the muscle atrophy or the vestibular system for the reason of the difficulty walking just after the return to the earth. On the other hand, we focus on the co-contraction of the antagonist muscle or the attitude control by vestibular and cerebellum. These results will provide the basic information to better understand the training program or rehabilitation.

SPACE APPLICATIONS

Crewmembers living on the International Space Station (ISS) for extended missions experience severe muscle atrophy. The soleus, a skeletal muscle in the lower calf that is associated with standing up, is known to atrophy and cause difficulty walking after astronauts return home. The Synergy investigation will determine how the soleus muscle and other muscles re-adapt to Earth gravity after spaceflight.

EARTH APPLICATIONS

Results from the Synergy investigation will help physicians develop rehabilitation methods for patients on prolonged bed rest, elderly people, or those with limited mobility.

OPERATIONAL REQUIREMENTS AND PROTOCOLS

At least 5 subjects are required. Pre and Post Baseline Data Collections (BDC) only, no in-flight measurements. To accomplish this experiment, subjects are required to complete all of the pre and post BDC measurements. The number of data collections are 5 times in total; 1 time in pre-flight (L-6(-0/+5) months) and 4 times in post-flight (R+0(-0/+4) days, R+7 (-3/+0) days, R+1(-0/+1) months, R+3(-0/+3) months). The distance between measurement i) and ii) should be more than 2 days.

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