Université de Strasbourg, Institut Pluridisciplinaire Hubert Curien, Département d'Ecologie, Physiologie et Ethologie, CNRS, UMR7178, Strasbourg, France.
J Appl Physiol (1985). 2011 Oct;111(4):1201-10. doi: 10.1152/japplphysiol.00698.2011. Epub 2011 Aug 11.
Although it is no longer debatable that sedentary behaviors are an actual cause of many metabolic diseases, the physiology of physical inactivity has been poorly investigated for this purpose. Along with microgravity, the physiological adaptations to spaceflights require metabolic adaptations to physical inactivity, and that is exceedingly well-simulated during the ground-based microgravity bed-rest analogs. Bed rest thus represents a unique model to investigate the mechanisms by which physical inactivity leads to the development of current societal chronic diseases. For decades, however, clinicians and physiologists working in space research have worked separately without taking full awareness of potential strong mutual questioning. This review summarizes the data collected over the last 60 years on metabolic adaptations to bed rest in healthy subjects. Our aim is to provide evidence that supports the hypothesis that physical inactivity per se is one of the primary causes in the development of metabolic inflexibility. This evidence will focus on four main tenants of metabolic inflexiblity: 1) insulin resistance, 2) impaired lipid trafficking and hyperlipidemia, 3) a shift in substrate use toward glucose, and 4) a shift in muscle fiber type and ectopic fat storage. Altogether, this hypothesis places sedentary behaviors upstream on the list of factors involved in metabolic inflexibility, which is considered to be a primary impairment in several metabolic disorders such as obesity, insulin resistance, and type 2 diabetes mellitus.
尽管久坐行为是许多代谢性疾病的一个实际病因已不再有争议，但为了这个目的，身体不活动的生理学尚未得到充分研究。与微重力一样，太空飞行的生理适应需要适应身体不活动的代谢适应，而在基于地面的微重力卧床模拟中，这可以得到极好的模拟。因此，卧床休息代表了一种独特的模型，可以研究身体不活动导致当前社会慢性疾病发展的机制。然而，几十年来，从事太空研究的临床医生和生理学家一直各自为政，没有充分意识到潜在的强烈相互质疑。这篇综述总结了过去 60 年来关于健康受试者卧床休息时代谢适应的研究数据。我们的目的是提供证据支持这样一种假设，即身体不活动本身就是代谢灵活性丧失的主要原因之一。这一证据将集中在代谢灵活性的四个主要方面：1）胰岛素抵抗，2）脂质转运受损和高脂血症，3）底物利用向葡萄糖转移，以及 4）肌肉纤维类型和异位脂肪储存的转移。总的来说，这个假设将久坐行为置于代谢灵活性丧失相关因素的列表之首，这被认为是几种代谢紊乱（如肥胖、胰岛素抵抗和 2 型糖尿病）的主要缺陷。
