BACKGROUND Living in walkable neighborhoods may provide long-term cardio-metabolic health benefits to residents. Little empirical research has examined the behavioral mechanisms in this relationship. In this longitudinal study, we examined the potential mediating role of physical activity (baseline and 12-year change) in the relationships of neighborhood walkability with 12-year changes in cardio-metabolic risk markers. METHODS The Australian Diabetes, Obesity and Lifestyle study collected data from adults, initially aged 25+ years, in 1999-2000, 2004-05, and 2011-12. We used 12-year follow-up data from 2023 participants who did not change their address during the study period. Outcomes were 12-year changes in waist circumference, weight, systolic and diastolic blood pressure, fasting and 2-h postload plasma glucose, high-density lipoprotein cholesterol, and triglycerides. A walkability index was calculated, using dwelling density, intersection density, and destination density, within 1 km street-network buffers around participants' homes. Spatial data for calculating these measures were sourced around the second follow-up period. Physical activity was assessed by self-reported time spent in moderate-to-vigorous physical activity (including walking). Multilevel models, adjusting for potential confounders, were used to examine the total and indirect relationships. The joint-significance test was used to assess mediation. RESULTS There was evidence for relationships of higher walkability with smaller increases in weight (P = 0.020), systolic blood pressure (P < 0.001), and high-density lipoprotein cholesterol (P = 0.002); and, for relationships of higher walkability with higher baseline physical activity (P = 0.020), which, in turn, related to smaller increases in waist circumference (P = 0.006), weight (P = 0.020), and a greater increase in high-density lipoprotein cholesterol (P = 0.005). There was no evidence for a relationship of a higher walkability with a change in physical activity during the study period (P = 0.590). CONCLUSIONS Our mediation analysis has shown that the protective effects of walkable neighborhoods against obesity risk may be in part attributable to higher baseline physical activity levels. However, there was no evidence of mediation by increases in physical activity during the study period. Further research is needed to understand other behavioral pathways between walkability and cardio-metabolic health, and to investigate any effects of changes in walkability.

中文翻译：

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邻里步行性和心脏代谢风险的12年变化：体力活动的中介作用。

背景技术生活在步行街区可以为居民提供长期的心脏代谢健康益处。很少有实证研究检查这种关系的行为机制。在这项纵向研究中，我们研究了体育活动（基线和12年变化）在邻里步行能力与心血管代谢危险标志物12年变化之间的潜在中介作用。方法澳大利亚糖尿病，肥胖与生活方式研究收集了1999-2000年，2004-05年和2011-12年最初年龄在25岁以上的成年人的数据。我们使用了2023名参与者的12年随访数据，这些参与者在研究期间未更改地址。结果是腰围，体重，收缩压和舒张压，空腹和负荷后2小时血糖12年变化，高密度脂蛋白胆固醇和甘油三酸酯。使用居住密度，交叉路口密度和目的地密度，在参与者房屋周围1 km的街道网络缓冲区内，计算了步行能力指数。用于计算这些量度的空间数据来自第二个随访期。通过自我报告的中度至剧烈运动时间（包括步行时间）评估运动量。使用针对潜在混杂因素进行调整的多级模型来检查总体和间接关系。联合显着性检验用于评估调解。结果有证据表明，较高的步行能力与较小的体重增加（P = 0.020），收缩压（P <0.001）和高密度脂蛋白胆固醇（P = 0.002）之间存在相关性；和，较高的步行能力与较高的基线体育活动之间的关系（P = 0.020），这又与腰围增加较小（P = 0.006），体重增加（P = 0.020）和高密度脂蛋白增加有关胆固醇（P = 0.005）。在研究期间，没有证据表明较高的步行能力与身体活动的变化相关（P = 0.590）。结论我们的中介分析表明，步行街区对肥胖风险的保护作用可能部分归因于较高的基线体育活动水平。但是，在研究期间，没有证据表明体育活动的增加可以起到调节作用。需要进一步研究以了解步行性和心脏代谢健康之间的其他行为途径，