Supplementary Material for: Light-Intensity Physical Activity in a Large Prospective Cohort of Older US Adults: A 21-Year Follow-Up of Mortality

<b><i>Background:</i></b> Studies show that regular moderate to vigorous physical activity is associated with a lower risk of cardiovascular disease, certain cancers, and premature death, but few studies have examined associations of light-intensity physical activity (LPA) and mortality, especially among older adults. <b><i>Objectives:</i></b> The aim of this study was to investigate the association of LPA with the risks of death from all causes, cancer, cardiovascular diseases, and respiratory diseases among older adults in the Cancer Prevention Study-II Nutrition Cohort (CPS-II NC). <b><i>Methods:</i></b> Analyses included 123,232 participants in CPS-II NC, among whom 46,829 died during follow-up (1993–2014). Cox proportional hazards regression models were used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI) for self-reported leisure time LPA associated with mortality. <b><i>Results:</i></b> Engaging in little or no LPA (&lt;3 metabolic equivalent [MET]-h/week) was associated with a 16% higher risk of all-cause mortality (HR 1.16, 95% CI 1.12–1.20) compared to engaging in some LPA (3 to &lt;9 MET-h/week) after adjusting for moderate to vigorous physical activity. However, there was no evidence of a dose-response relationship. A statistically significant interaction with age suggested that more LPA was associated with a lower risk of respiratory disease mortality only among participants aged ≥70 years (21+ vs. 3 to &lt;9 MET-h/week, HR 0.78, 95% CI 0.66–0.91; <i>p</i>_int = 0.003). <b><i>Conclusions:</i></b> In this prospective study of older adults, accumulating little/no leisure time LPA was associated with a higher risk of mortality. It is of substantial public health value to demonstrate the potential benefits of engaging in any activity, even if light in intensity, among older adults given the aging US population.

**<i>背景：</i>** 已有研究表明，规律的中等至高强度体力活动与更低的心血管疾病、部分癌症及过早死亡风险相关，但目前鲜有探讨轻强度体力活动（light-intensity physical activity, LPA）与死亡率之间关联的研究，尤其是在老年人群体中。
**<i>研究目标：</i>** 本研究旨在探讨癌症预防研究-II营养队列（Cancer Prevention Study-II Nutrition Cohort, CPS-II NC）中老年人的轻强度体力活动与全因死亡、癌症死亡、心血管疾病死亡及呼吸系统疾病死亡风险之间的关联。
**<i>研究方法：</i>** 本次分析纳入CPS-II NC队列的123232名参与者，随访周期为1993年至2014年，期间共有46829名参与者死亡。本研究采用Cox比例风险回归模型，估算自我报告的闲暇时间轻强度体力活动与死亡率相关的风险比（hazard ratio, HR）及95%置信区间（95% confidence interval, 95% CI）。
**<i>研究结果：</i>** 在校正中等至高强度体力活动因素后，几乎不进行或未进行轻强度体力活动（<3代谢当量[metabolic equivalent, MET]-小时/周）的人群，其全因死亡风险较进行一定量轻强度体力活动（3至<9 MET-小时/周）的人群升高16%（HR=1.16，95%CI=1.12~1.20）。但未观察到明确的剂量-反应关系。与年龄存在具有统计学意义的交互作用：仅在70岁及以上的参与者中，更高的轻强度体力活动量与更低的呼吸系统疾病死亡风险相关（21+ MET-小时/周 对比 3至<9 MET-小时/周，HR=0.78，95%CI=0.66~0.91；交互作用P值=0.003）。
**<i>研究结论：</i>** 本项针对老年人群的前瞻性研究显示，闲暇时间几乎不进行或未进行轻强度体力活动与更高的死亡风险相关。鉴于美国人口老龄化趋势，证实老年人群开展任何强度活动（即便为轻强度活动）的潜在获益，具有重要的公共卫生价值。