长期坐姿对疾病的影响

kingburg

http://diabetes.diabetesjournals ... bstract/db07-0882v1

The Role of Low Energy Expenditure and Sitting on Obesity, Metabolic Syndrome, Type 2 Diabetes, and Cardiovascular Disease
Marc T. Hamilton, Ph.D.1,,2, Deborah G. Hamilton, M.S.1, and Theodore W. Zderic, Ph.D.1

It is not uncommon for people to spend one-half of their waking day sitting, with relatively idle muscles. The other half includes the often large volume of non-exercise physical activity. Given the increasing pace of technological change in their domestic, community and workplace environments, modern humans may still not have reached the historical pinnacle of physical inactivity, even in cohorts where people already do not perform exercise. Our purpose here is to examine the role of sedentary behaviors, especially sitting, on mortality, cardiovascular disease, type 2 diabetes, metabolic syndrome risk factors, and obesity. Recent observational epidemiological studies strongly suggest that daily sitting time or low non-exercise activity levels may have a significant direct relationship with each of these medical concerns. There is now a need for studies to differentiate between the potentially unique molecular, physiologic, and clinical effects of too much sitting (inactivity physiology) separate from the responses caused by structured exercise (exercise physiology). In theory, this may be in part because Non-Exercise Activity Thermogenesis (NEAT) is generally a much greater component of total energy expenditure than exercise, or because any type of brief, yet frequent muscular contraction throughout the day may be necessary to short-circuit unhealthy molecular signals causing metabolic diseases. One of the first series of controlled laboratory studies providing translational evidence for a molecular reason to maintain high levels of daily low-intensity and intermittent activity came from examinations of the cellular regulation of skeletal muscle lipoprotein lipase (a protein important for controlling plasma triglyceride catabolism, HDL-C, and other metabolic risk factors). Experimentally reducing the normal spontaneous standing and ambulatory time had a much greater effect on LPL regulation, compared to adding vigorous exercise training on top of the normal level of non-exercise activity. Those studies also found that inactivity initiated unique cellular processes that were qualitatively different from the exercise responses. In summary, there is an emergence of inactivity physiology studies. These are beginning to raise a new concern with potentially major clinical and public health significance: the average non-exercising person may become even more metabolically unfit in the coming years if they sit too much -- thereby limiting the normally high volume of intermittent non-exercise physical activity in everyday life. Thus, if the inactivity physiology paradigm is proven to be true, the dire concern for the future may rest with growing numbers of people unaware of the potential insidious dangers of sitting too much, and who are not taking advantage of the benefits of maintaining non-exercise activity throughout much of the day.

（来自丁香园的译文）

低能量消耗和长期坐姿对肥胖、代谢综合征、2型糖尿病和心血管疾病的影响

很多情况下，人们在醒着的时候至少有一半时间是坐着的，全身放松；而另一半的时间又有绝大多数是非运动型的活动。但鉴于目前生活和工作节奏的增快，现代人类可能还是没有达到历史上体力活动的最少量时期。

我们研究的目的就是调查长期坐姿对于死亡率、心血管疾病、2型糖尿病、代谢综合征危险因素和肥胖的影响。最近的观察性流行病学调查强烈显示，每天的坐姿和非运动型活动的时间与上述的疾病状态有直接的关联。现在，需要进行一些研究将长期坐姿（静止生理学）与体育锻炼（运动生理学）的潜在的独特的分子、生理和临床的效应区别开来。

从理论上来说，这样的结果部分是由于非运动型活动的产热作用比锻炼占据了更多比例的能量消耗，或者是由于长时间短暂、频繁的肌肉收缩造成短途的不健康的分子通路，后者则是代谢综合征中的必经途径。最初的一系列研究提供了一些来自于骨骼肌脂蛋白脂肪酶翻译水平的证据，从分子机制解释了每日低强度和间歇性运动的细胞调节机制。与在正常水平的非运动式活动基础上增加高强度活动训练相比，在实验中减少正常自发的站立和活动的时间对于LPL的调节具有重大的影响。这些研究还发现，缺乏运动所激发的独特的细胞反应与锻炼有着质的区别。这些研究也引起了对这种潜在的临床和大众健康影响的关注：如果坐得太多，这些平时都缺乏运动的人可能在未来几年产生代谢上的不适，因为长期的坐姿限制了在每日生活中进行的间歇性的非运动型活动的时间。

因此，如果这种缺乏活动的理论成立，这种可怕的担忧就可能出现在不断增加的对长期坐姿的隐匿性危害不作重视的人群身上，而这些人往往也不懂得每日保持非运动型活动的益处。