Doctoral Dissertation Research: Evolutionary mismatch and variation in physical activity and function

人类进化到了适度的体力活动，每天步行的距离比许多人现在习惯的距离更长，通常是在搬运东西的情况下，并从事许多其他与生存相关的任务，包括身体运动。有规律的体力活动(PA)是人类环境中如此重要的一部分，以至于长时间不参加会增加许多疾病和状况的风险，包括下腰痛(LBP)，这是世界上最常见的肌肉骨骼疾病。尽管有很多因素在起作用，但最能预测LBP的是躯干肌肉的耐力。躯干肌肉和脊柱负荷的耐力在很大程度上取决于一个人经常进行的PA的数量和类型。为了更好地了解PA如何影响躯干和脊柱功能，这个博士论文研究项目研究了参与高PA水平的人，例如每天步行很长距离并持续从事体力劳动的人，与每天久坐不动的人相比，这些人经常背着水、食物和婴儿。该项目为当地社区成员和研究人员提供研究、培训和合作机会。这个项目检验的主要假设是，PA减少会导致躯干肌肉活动和脊柱负荷水平降低，这与躯干肌肉耐力下降有关。为了验证这一假设，测量身体运动和背部肌肉活动的新型可穿戴传感器与基于计算机的肌肉骨骼建模相结合，以比较农村(高活动)和城市(低活动)人群的脊柱负荷和背部肌肉激活水平，以评估脊柱负荷和背部肌肉激活水平的差异是否与躯干肌肉耐力有关。该项目还使用可穿戴传感器来测试躯干肌肉耐力如何影响两种假设与腰痛有关的脊柱功能：行走过程中脊柱僵硬的调节，以及行走过程中脊柱产生的压缩和剪力的分布。通过利用两个具有不同PA特征的人群生活在地理上邻近的研究设计，该项目解决了为什么以及如何在不同水平上参与PA可以帮助我们的身体，特别是我们的背部和脊椎，更好地发挥功能，保持无腰痛。最终，这项研究的结果可以帮助我们理解我们的现代活动水平如何可能与整个人类进化过程中经历的活动水平不匹配。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Humans evolved to be moderately physically active, walking longer distances daily than many are currently used to, often while carrying things, and engaging in many other subsistence-related tasks that involve bodily movement. Regular physical activity (PA) is such an important part of the human environment that its prolonged absence increases the risk for numerous diseases and conditions including lower back pain (LBP), the most common musculoskeletal condition in the world. Although many factors contribute, the strongest predictor of LBP is the endurance of trunk muscles. The endurance of trunk muscles and spine loading depend largely on how much and what types of PA a person routinely engages in. To better understand how PA affects the trunk and spine function, this Doctoral Dissertation Research project studies people engaging in high levels of PA such as walking long distances each day and consistently engaging in manual labor, often while carrying water, food, and infants, compared to people with more sedentary daily activity levels. The project provides research training and collaboration opportunities for local community members and researchers. The primary hypothesis tested by this project is that reduced PA generates low levels of trunk muscle activity and spinal loading which are associated with low trunk muscle endurance. To test this hypothesis, novel wearable sensors that measure bodily movement and back muscle activity are combined with computer-based musculoskeletal modeling to compare spinal loading and back muscle activation levels between rural (high-activity) and urban (low-activity) populations to assess whether differences in spinal loading and back muscle activation levels are associated with trunk muscle endurance. The project also uses wearable sensors to test how trunk muscle endurance affects two spine functions hypothesized to be associated with LBP: modulation of spine stiffness during walking and the distribution of compression and shear forces generated in the spine during walking. By making use of a research design where two populations with different PA profiles live in geographic proximity, this project addresses why and how engaging in PAs at different levels may help our bodies, and specifically our backs and spines, function better and stay LBP-free. Ultimately the results of this research can contribute to our understanding of how our modern activity levels may be a mismatch for the levels of activity experienced throughout human evolution.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.