Bone strength and physical activity over the lifecourse

在现代人类骨骼中，有许多遗传、行为和生活史因素与骨量有关。先前对动物模型、人类临床和考古样本的研究表明，体育活动与骨量之间存在正相关关系。然而，从具有非常高活动水平和病原体负荷的现代人类群体中获得的具有人口代表性的样本数据很少。该项目将研究这些人群的骨量，以促进我们对骨量、人口历史、能量学和生命周期中身体活动之间复杂关系的理解。拟议的研究将促进我们对现代人类骨骼进化和适应的理解，以及在包括美国在内的许多工业化社会中发现的久坐不动的生活方式对骨骼的影响。该项目将为研究生和本科生提供培训机会，支持国际研究合作和公共科学推广活动。并为非工业化人口提供与骨骼相关的数据，以建立一个更大的人种学和生物学数据库。与过去的人群相比，缺乏运动被认为是现代人骨骼柔软的原因之一，这一观点是基于负重和肌肉收缩的冲击力会引发骨骼沉积，这一过程被称为“骨骼功能适应”。这一观点得到了运动员和运动干预研究的充分支持，根据这一观点，骨骼通过增加骨组织和改变其在最高弯曲应变方向的横截面分布来适应身体活动的需求。然而，骨骼功能适应的人类学研究尚未充分探索活动概况、饮食、感染负担和身体成分（如肌肉质量）对骨骼的潜在相互作用和/或混淆影响。该项目将测试更高的体育活动水平，包括在儿童时期，是否会导致更高的骨骼强度，以及更高的骨骼强度是否会减轻与年龄相关的骨质流失和骨折风险。该项目还将检查骨骼生长在多大程度上对习惯性的、体力密集的生存活动作出反应，受到能量限制和高病原体负担的限制。为了解决这些问题，研究小组将1)使用胫骨、股骨、桡骨和肱骨的定量计算机断层扫描（pQCT）对手臂和腿骨结构进行成像；2)测量身体活动水平以检验机械载荷对骨结构的影响；3)考察工业化程度、骨折家族史和社会经济因素对体力活动水平与骨强度关系的影响；4)记录低骨量的患病率和结构相关性。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

There are a number of genetic, behavioral and life history factors associated with bone mass in the modern human skeleton. Previous research in animal models, and in human clinical and archaeological samples, has shown a positive relationship between physical activity and bone mass. However, few data are available for population-representative samples from modern human groups with very high activity levels and pathogen loads. This project will study bone mass in such a population, in order to advance our understanding of the complex relationships among bone mass, population history, energetics, and physical activity across the lifespan. The proposed research will advance our understanding of modern human skeletal evolution and adaptation, as well as the skeletal impacts of the sedentary lifestyle found in many industrialized societies including the U.S. This project will provide training opportunities for graduate and undergraduate students, support international research collaborations and public science outreach activities, and contribute bone-related data to a larger ethnographic and biological database for a non-industrialized population.Physical inactivity, relative to past populations, is thought to contribute to modern human skeletal gracility, based on the idea that impact forces from load bearing and muscle contraction trigger bone deposition, a process called "bone functional adaptation." According to this idea, which is well supported by studies of athletes and exercise interventions, bone adapts to the demands of physical activity both by adding bone tissue and altering its cross-sectional distribution in the direction of the highest bending strains. However, anthropological studies of bone functional adaptation have not fully explored the potentially interactive and/or confounding effects of activity profiles, diet, infectious burden and body composition (e.g. muscle mass) on bone. This project will test whether higher physical activity levels, including in childhood, lead to greater bone strength, and whether greater bone strength mitigates age-related bone loss and fracture risk. The project will also examine the extent to which bone growth in response to habitual, physically-intensive subsistence activities is constrained by energetic limitations and high pathogen burden. To address these questions, the research team will 1) image arm and leg bone structure using quantitative computed tomography (pQCT) of the tibia, femur, radius and humerus; 2) measure physical activity levels to examine effects of mechanical loading on bone structure; 3) examine how degree of industrialization, family history of fractures, and socio-economic factors impact the relationship between physical activity levels and bone strength; and 4) document prevalence and structural correlates of low bone mass.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.