Abstract: Background Low back pain（LBP）in middle-aged and elderly adults has become a significant public health issue worldwide. Physical activity and sleep are two core components of the 24-hour lifecycle，and maintaining adequate physical activity and good sleep are crucial for health，both of which are associated with LBP. Objective To investigate the prevalence of LBP in middle-aged and elderly adults in China，analyze the independent and combined effects of physical activity and sleep on its occurrence，and provide scientific evidence for behavioral health. Methods Based on the 2018 China Health and Retirement Longitudinal Study，participants without demographic，physical activity，sleep，and LBP data were excluded. A total of 13 496 eligible individuals aged 45 to 69 were included，and their demographic and behavioral information was collected. Binary logistic regression and multiple linear regression were used to examine the relationship between physical activity，sleep duration，and LBP，and a mediation model was constructed to analyze the mediating effect of sleep duration on the association between physical activity and LBP. Results The prevalence of LBP among the 13，496 participants was 39.0%（n=5 269）.Inadequate sleep（<7 hours）was reported by 57.1%（n=7 704）of middle-aged and elderly adults in China，with 11.6%（n=1561）engaging in mild physical activity and 88.4%（n=11 935）engaging in moderate to high-intensity physical activity. The multicollinearity diagnosis results for confounding variables（e.g.，gender，age，alcohol consumption，and smoking） showed that all variance inflation factors were less than 5，indicating no collinearity. Regression analysis revealed a positive correlation between physical activity and LBP（β=0.120，P<0.05），a negative correlation between sleep duration and LBP（β=-0.220，P<0.01），and a negative correlation between physical activity and sleep duration（β=-0.081，P<0.05）. The mediation analysis of categorical variables indicated Z=2.223>1.96，and the path from physical activity to LBP was not significant（β=0.105，P>0.05），suggesting a complete mediating effect of sleep duration on the association between physical activity and LBP. Conclusion Over one-third of middle-aged and elderly adults in China suffer from LBP. Higher levels of physical activity or shorter sleep duration are associated with increased risk of LBP. Sleep duration plays a complete mediating role in the association between physical activity and LBP，where the increased risk of LBP associated with high-intensity physical activity is completely transmitted through reduced sleep duration. Adequate sleep duration plays an important role in reducing the risk of LBP associated with high-intensity physical activity. This study suggests that older adults should adjust their exercise intensity according to their own conditions and maintain adequate sleep duration to reduce the risk of LBP.

Key words: Low back pain, Physical activity, Sleep duration, Middle-aged and elderly adults

摘要： 背景 中老年人腰背痛已成为世界范围内重要的公共卫生问题，身体活动和睡眠是占据24h生命周期的两个核心生活方式组成部分，坚持充足的身体活动和良好的睡眠对健康至关重要，且两者均与腰背痛有关。目的 调查我国中老年人腰背痛发病率，分析身体活动和睡眠两大行为要素对其发病的独立影响和联合影响，为行为健康提供科学依据。方法 基于2018年中国健康与养老追踪调查，排除没有提供人口学、身体活动、睡眠和腰痛数据的参与者，筛选出符合标准的45~69岁中老年13496例，收集其一般人口学信息和行为相关信息。采用二元Logistic回归和多元线性回归检验身体活动、睡眠时间和腰背痛三者之间的关系，并构建睡眠时间在身体活动与腰背痛之间的中介模型进行中介作用分析。结果 13496例调查对象腰背痛患病率为39.0%（5269/13496）；我国中老年人睡眠不足（<7h）占比57.1%（7704/13496）；轻度和中高强度身体活动占比分别为11.6%（1561/13496）和88.4%（11935/13496）。对混杂变量（如性别、年龄、饮酒和吸烟）多重共线诊断结果显示，方差膨胀因子均<5，排除共线性。回归分析结果显示，身体活动与腰背痛患病呈正相关（β=0.120，P<0.05），睡眠时间与腰背痛患病呈负相关（β=-0.220，P<0.01），身体活动与睡眠时间呈负相关（β=-0.081，P<0.05）。根据类别变量中介效应分析得出Z=2.223>1.96，且身体活动影响腰背痛的路径不显著（β=0.105，P>0.05），故睡眠时间在身体活动与腰背痛的关联中发挥完全中介效应。结论 有超过1/3的中国中老年人患有腰背痛，身体活动水平越高或睡眠时间越短，腰背痛患病风险越高，睡眠时间在身体活动与腰背痛发挥完全中介效应，即高强度身体活动所带来的腰背痛风险经由睡眠时间锐减所完全传递，充足的睡眠时间在降低高强度身体活动所带来的腰背痛发病风险中发挥重要作用。提示老年人在进行体育锻炼时，应根据自身情况合理安排运动量，并保持充足的睡眠时间，以降低腰背痛患病风险。

关键词: 腰背痛, 身体活动, 睡眠时间, 中老年人