ニシムラ　ナオキ   NISHIMURA, Naoki   西村　直記 スポーツ科学部 スポーツ科学科 教授
言語種別	英語
発行・発表の年月	2017
形態種別	学術雑誌
査読	査読あり
標題	Adaptation to microgravity, deconditioning, and countermeasures
執筆形態	共同
掲載誌名	J Physiol Sci
掲載区分	国内
巻・号・頁	67,pp.271-281
著者・共著者	Kunihiko Tanaka, Naoki Nishimura, Yasuaki Kawai
概要	Humans are generally in standing or sitting positions on Earth during the day. The musculoskeletal system supports these positions and also allows motion. Gravity acting in the longitudinal direction of the body generates a hydrostatic pressure difference and induces footward fluid shift. The vestibular system senses the gravity of the body and reflexively controls the organs. During spaceflight or exposure to microgravity, the load on the musculoskeletal system and hydrostatic pressure difference is diminished. Thus, the skeletal muscle, particularly in the lower limbs, is atrophied, and bone minerals are lost via urinary excretion. In addition, the heart is atrophied, and the plasma volume is decreased, which may induce orthostatic intolerance. Vestibular-related control also declines; in particular, the otolith organs are more susceptible to exposure to microgravity than the semicircular canals. Using an advanced resistive exercise device with administration of bisphosphonate is an effective countermeasure against bone deconditioning. However, atrophy of skeletal muscle and the heart has not been completely prevented. Further ingenuity is needed in designing countermeasures for muscular, cardiovascular, and vestibular dysfunctions.