Collaborative Research: The Evolutionary Biology and Health Consequences of Human Inactivity

最近的研究表明，久坐不动的生活，特别是长时间的西式椅子坐，与心血管疾病（CVD）的高水平，这表明这种行为可能是西方社会CVD相关发病率和死亡率升高的重要组成部分。这种增加的风险归因于坐着引起的下肢肌肉活动减少，同时减少了从血液中虹吸脂肪的酶的产生。其他文化中的人也经常长时间不活动，但似乎没有患上同样的心血管疾病风险。因此，休息的方式可能比坐着的时间更重要，而其他社会的人们休息的方式可以保持肌肉活动，从而降低心血管疾病的风险。例如，蹲下可能需要类似于站立的肌肉活动水平，这可能是非西方社会中休息姿势的一种突出形式，这可能与增强心血管健康有关。由于这种休息行为可能具有类似的早期人类祖先的特征，与休息姿势形式的改变相关的健康成本也可能具有进化基础。 这项研究验证了一个假设，即与西方坐姿相比，非西方社会的坐姿增加了肌肉活动，改善了血脂水平，从而促进了有益的健康效果。对这一假设的初步测试将需要对当代人类狩猎采集者（坦桑尼亚的哈扎人）进行实地研究，以研究传统人类的休息和不活动方式。 其次，针对有蹲姿经历的受试者群体，将采用随机交叉实验设计来测量长时间蹲姿与坐椅后的肌肉活动和血脂变化。使用这些方法，该研究将探索在健康和幸福的背景下休息姿势的进化和当代人类生物学。 作为第一项从跨文化和进化的角度明确研究人类不活动的研究，该项目将改变我们目前对久坐不动的生活方式如何影响现代人类生理功能的理解。在评估这种行为对美国疾病和死亡率相关的人类生物学的影响时，这项工作也可以转化为改善西方社会公共健康的行为干预措施，以及在向更西式的不活动模式过渡的社会中的应用。

Recent research has associated sedentary living, and specifically, long periods of Western-style chair-sitting, with high levels of cardiovascular disease (CVD), suggesting that such behavior may be an important component of elevated rates of CVD-related morbidity and mortality in Western society. This increased risk has been attributed to a sitting-induced reduction in lower limb muscle activity, with concurrent decrease in the production of enzymes that siphon fat from the blood stream. Individuals in other cultures also are often inactive for long periods of time, yet do not seem to develop the same risk of CVD. It therefore is possible that styles of resting are more important than time spent sitting, and that people in other societies rest in ways that maintain muscle activity and thereby reduce cardiovascular disease risk. For example, it may be that squatting, potentially requiring levels of muscle activity similar to standing, is a prominent form of resting posture in non-Western societies which can be related to enhanced cardiovascular health. And as such resting behavior may have similarly characterized early human ancestors, the health costs associated with alteration in forms of resting posture also may have an evolutionary basis. This research tests the hypothesis that the style of sitting in non-Western societies increases muscle activity and improves blood lipid profiles compared to Western-style sitting, thereby promoting beneficial health effects. Initial testing of this hypothesis will entail a field study of contemporary human hunter-gatherers (the Hadza people of Tanzania) in order to examine styles of rest and inactivity in traditionally-living humans. Second, focusing on a population of subjects experienced in squatting, a randomized crossover experimental design will be employed to measure muscle activity and changes in blood lipids following prolonged periods of squatting versus chair-sitting. Using these methods, the research will explore the evolutionary and contemporary human biology of resting postures in the context of health and well-being. As the first study to explicitly examine human inactivity from a cross-cultural and evolutionary perspective, this project will transform our current understanding of how more sedentary lifestyles impacted functionality of modern human physiology. And in the assessment of the impact of such behavior on human biology relevant to disease and mortality rates in the US, this work also could find translation into behavioral interventions which improve public health in Western societies, as well as application in societies undergoing transitions to more Western-style inactivity patterns.