Understanding associations between timing of physical activity and health outcomes in young adults

摘要 为了预防和管理慢性病，国家指南要求至少150分钟的中度到 每周进行剧烈的体育活动；然而，人们对一天中什么时候进行这项活动最好知之甚少。 体力活动的时机对于容易受到社交时差影响的年轻人来说可能特别重要 (即生物节律和睡眠/觉醒行为之间的差异)，使他们面临更高的风险 罹患慢性病。对成人样本的研究表明，晨练可能有益于 体重管理和/或心脏代谢危险因素；然而，缺乏对 支持这些发现。此外，人们对体力活动的时间和健康结果知之甚少。 在生理上与成年同龄人不同并面临更高风险的年轻人中 社会时差/生理失调。我们的目标是检查横截面和纵向关系 体力活动时间与体重和心脏代谢危险因素在一组患高血压的年轻人队列中的关系 心脏代谢疾病。具体地说，我们将使用来自健康身体健康大学(HBHU)试验的数据 [NIH/NIDDK R01 DK100916]，一项已完成的青年两部位体重管理随机对照试验 成年人，年龄18-35岁。我们将使用Actigraph加速度计测量的客观体力活动数据 识别活动时间类别的四个时间点(基准、6个月、12个月、18个月)(即，上午， 下午、晚上、夜间)，并检查基线上的差异以及活动随时间的变化 每一时间类别都与健康结果有关(即体重、心脏代谢风险因素)。我们假设 那就是：1)早晨的活动与较低的基线体重和较大的体重减轻有关。 随访，2)晨间活动将与较少的心脏代谢危险因素相关 这些危险因素在随访中的减少，3)晨间活动和 体重/心脏代谢风险因素的改善将通过每周更多的中等至 剧烈的身体活动，以及4)年龄、性别和干预状态将缓和这种关系。这个 拟议的研究在以下方面是创新的：(A)使用18个月的纵向数据来测试 活动和健康结果的时间安排；(B)使用高危青年样本；以及(C)使用 随机对照设计，以测试基于技术的健康信息干预对 利益相关者协会。我们研究的长期目标是为设计以时间为重点的理论- 针对高危年轻人的行为改变干预措施。

ABSTRACT To prevent and manage chronic disease, national guidelines call for a minimum of 150 minutes of moderate-to- vigorous physical activity per week; yet little is known about what time of day is best for performing this activity. The timing of physical activity may be particularly important for young adults who are vulnerable to social jetlag (i.e., discrepancy between biological rhythms and sleep/wake behaviors), placing them at increased risk of developing chronic diseases. Research in adult samples indicates that morning activity may be beneficial for weight management and/or cardiometabolic risk factors; however, there is a lack of longitudinal studies to support these findings. Furthermore, little is known about the timing of physical activity and health outcomes among young adults who are physiologically different from their adult counterparts and at increased risk of social jetlag/circadian misalignment. We aim to examine the cross-sectional and longitudinal relationships of physical activity timing with weight and cardiometabolic risk factors in a cohort of young adults at risk for cardiometabolic disease. Specifically, we will use data from the Healthy Body Healthy U (HBHU) trial [NIH/NIDDK R01 DK100916], a completed two-site weight management randomized controlled trial for young adults, ages 18-35. We will use objective physical activity data measured via the ActiGraph accelerometer at four time-points (Baseline, Month 6, Month 12, Month 18) to identify activity time categories (i.e., morning, afternoon, evening, night-time) and examine how differences at baseline, and changes over time, in activity during each time category relate to health outcomes (i.e., weight, cardiometabolic risk factors). We hypothesize that: 1) morning activity will be associated with lower weight at baseline and greater weight loss over the follow-up, 2) morning activity will be associated with fewer cardiometabolic risk factors at baseline and reductions in these risk factors over the follow-up, 3) the proposed associations between morning activity and improved weight/cardiometabolic risk factors will be mediated by greater weekly volumes of moderate-to- vigorous physical activity, and 4) age, sex, and intervention status will moderate the relationships. The proposed study is innovative in (a) its use of longitudinal data over 18 months to test associations between timing of activity and health outcomes, (b) its use of an at-risk young adult sample and (c) its use of a randomized controlled design to test the impact of a technology-based health messaging intervention on the associations of interest. The long-term goal of our research is to inform the design of timing-focused, theory- based behavior change interventions for at-risk young adults.