Background Few studies have analyzed sensor-derived metrics of mobility abilities and total daily physical activity (TDPA). We tested whether sensor-derived mobility metrics and TDPA indices are independently associated with mobility disabilities. Methods This cohort study derived mobility abilities from a belt-worn sensor that recorded annual supervised gait testing. TDPA indices were obtained from a wrist-worn activity monitor. Mobility disability was determined by self-report and inability to perform an 8-feet walk task. Baseline associations of mobility metrics and TDPA (separately and together) were examined with logistic regressions and incident associations (average 7 years follow-up) with Cox models. Mediation analysis quantified the extent mobility metrics mediate the association of TDPA with mobility disability. Results 724 ambulatory older adults (mean age 82 years, 77.4% female) were studied. In separate models, mobility abilities (e.g. step time variability, turning angular velocity) and TDPA were related to mobility disabilities. Examined together in a single model, mobility abilities remained associated with mobility disabilities, while TDPA was attenuated. This attenuation of TDPA could be explained by mediation analysis that showed about 50% of TDPA associations with mobility disabilities is mediated via mobility abilities (prevalent mobility disability 54%, incident mobility disability 40%, incident loss of ambulation 50%; all p’s<0.001). Conclusions Sensor-derived mobility metrics assess more diverse facets of mobility. These metrics mediate approximately half of the association of higher levels of daily physical activity with reduced mobility disability in older adults. Findings may inform the design of targeted interventions to reduce mobility disability in late life.

中文翻译：

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活动能力介导了老年人更积极的生活方式与行动障碍的关联


背景 很少有研究分析传感器衍生的行动能力和每日总身体活动 （TDPA） 指标。我们测试了传感器衍生的活动指标和 TDPA 指数是否与行动障碍独立相关。方法 这项队列研究从记录年度监督步态测试的腰带传感器中获得活动能力。TDPA 指数是从腕戴式活动监测器获得的。行动障碍是由自我报告和无法执行 8 英尺步行任务确定的。使用 Cox 模型进行 logistic 回归和事件关联 （平均 7 年随访） 检查流动性指标和 TDPA （单独和一起） 的基线关联。中介分析量化了移动性指标介导 TDPA 与行动障碍关联的程度。结果 研究了 724 名非卧床老年人 （平均年龄 82 岁，77.4% 为女性）。在单独的模型中，移动能力 （例如 步长时间变化、转弯角速度） 和 TDPA 与移动障碍有关。在一个模型中一起检查，活动能力仍然与行动障碍相关，而 TDPA 则减弱。TDPA 的这种减弱可以通过中介分析来解释，该分析显示大约 50% 的 TDPA 与行动障碍的关联是通过行动能力介导的 （普遍行动障碍 54%，事件行动障碍 40%，事件性行走丧失 50%;所有 p's<0.001）。结论 传感器衍生的移动性指标评估了移动性的更多样化方面。这些指标介导了老年人更高水平的日常身体活动与行动不便的关联中的大约一半。 研究结果可能为设计有针对性的干预措施提供信息，以减少晚年的行动障碍。