Supplementary Material for: Subjective Health and Physical-Activity Engagement across Adulthood: Distinguishing between Within-Person and Between-Person Associations

Introduction: It is assumed that age-related increases in loss (e.g., health decline) motivate behavioral changes (e.g., prevention of health decline) across adulthood. This assumption has rarely been directly tested in empirical research, and the current study seeks to fill this gap. Methods: By performing random intercept cross-lagged panel model and multilevel modeling analyses on a three-wave longitudinal dataset from the Midlife in the United States survey (N = 7,108; 51.6% female; between 20 and 75 years at T1), we examined the between-person and the within-person associations between subjective health and engagement in physical activity. Chronic conditions, difficulty in performing daily activities, and demographic variables were controlled for. Results: At the between-person level, subjective (i.e., self-rated) health was positively associated with physical activity in the whole sample and the older subgroup (T1 age >55 years), but not in the younger subgroup (T1 age Discussion: This study revealed various associations between subjective health and engagement in physical activity across levels (the within- vs. between-person level) and across age groups (younger vs. older group). The finding contributes to a better understanding of people’s health behavior in reaction to health decline at different ages. It also supports the proposition that age-related intraindividual increases in losses (e.g., health decline) motivate behaviors that counteract such losses (e.g., physical activity that protects health).

引言：学界普遍假设，成年阶段中与年龄相关的损失（如健康衰退）会驱动个体做出行为改变（如预防健康衰退）。这一假设极少在实证研究中得到直接检验，本研究旨在填补这一研究空白。
方法：本研究针对来自美国中年发展追踪调查（Midlife in the United States survey）的三波纵向数据集（样本量N=7108，女性占比51.6%，首次调查T1时参与者年龄为20~75岁），采用随机截距交叉滞后面板模型（random intercept cross-lagged panel model）与多层建模（multilevel modeling）分析，检验了主观健康与体育锻炼参与度之间的个体间与个体内关联。研究控制了慢性疾病、日常活动能力障碍以及人口统计学变量。
结果：在个体间层面，全样本与老年亚组（T1年龄>55岁）的主观健康（即自我评定健康）与体育锻炼呈正相关，但年轻亚组（T1年龄
讨论：本研究揭示了主观健康与体育锻炼参与度在不同层面（个体内与个体间层面）以及不同年龄组（年轻组与老年组）之间存在多样化关联。该研究结果有助于更深入地理解不同年龄群体针对健康衰退所做出的健康行为反应，同时也支持了如下命题：与年龄相关的个体内损失（如健康衰退）的增加，会促使个体采取抵消此类损失的行为（如有益于健康的体育锻炼）。