Erratum: Habitual Physical Activity and Physical Fitness in Older Japanese Adults: The Nakanojo Study

Background: Optimal patterns of habitual physical activity to ensure healthy aging remain unclear because of measurement limitations; most investigators have used either subjective questionnaires, or accelerometer or pedometer measurements limited to a single week, despite evidence of both the limited reliability/validity of questionnaires and seasonal changes in activity patterns. Objective: This study explored possible associations between indicators of physical fitness (walking ability, upper- and lower-extremity isometric strength, and static and dynamic balance) and yearlong pedometer/accelerometer assessments of the quantity and quality of habitual physical activity in ostensibly healthy older adults. Methods: Subjects were 76 male and 94 female Japanese aged 65–84 years. Each participant wore a pedometer/accelerometer for 1 year; measurements included the average number of steps taken each day and the duration of activity at an intensity of >3 metabolic equivalents (METs). Compliance was good, the instrument being removed for intervals of >3 h on <5% of days; data for such intervals were excluded from analysis. At the year’s end, traditional laboratory techniques assessed preferred and maximal walking speeds, peak handgrip force, peak knee extension torque, total body sway, and maximal functional reach. Results: After controlling data for age and/or sex, lower-extremity function (walking speeds and knee extension torque) showed significant positive relationships with the daily step count and daily duration of activity at >3 METs, especially in individuals ≥75 years of age. On the other hand, handgrip force and body sway were unrelated to pedometer/accelerometer measurements. Linear and exponential regressions showed positive associations between walking speeds and pedometer/accelerometer scores up to the observed maxima of 13,700 steps/day and 62 min/day at >3 METs. However, when data were categorized into quartiles, walking speeds were not significantly greater in persons exceeding 7,000–8,000 steps/day and/or 15–20 min/day at >3 METs. With a few exceptions, subjects meeting these levels of habitual activity had walking speeds above the threshold predicting the development of functional dependence. Conclusion: The present data suggest that fitness is well maintained in elderly people who take >7,000–8,000 steps/day and/or spend >15–20 min/day at >3 METs. Nevertheless, the direction of this association merits exploration by longitudinal prospective studies and/or randomized controlled trials.

研究背景：由于测量方法存在局限，保障健康老龄化的日常身体活动最优模式仍不明确；既往多数研究者仅采用主观问卷，或是仅开展为期一周的计步器/加速度计（pedometer/accelerometer）测量，尽管已有证据表明问卷的信度与效度有限，且活动模式存在季节变化。
研究目的：本研究旨在针对表面健康的老年受试者，分析身体机能指标（步行能力、上下肢等长肌力、静态与动态平衡能力）与为期一年的计步器/加速度计对日常身体活动总量与质量的评估结果之间的潜在关联。
研究方法：受试者为76名男性与94名日本老年人群，年龄介于65至84岁之间。所有受试者佩戴计步器/加速度计时长为1年，测量指标包括每日平均步数，以及运动强度超过3代谢当量（metabolic equivalents, METs）的活动时长。受试者依从性良好，仪器被摘除超过3小时的天数占比不足5%，此类时段的数据均被排除在分析之外。研究结束时，采用传统实验室测试方法评估了受试者的自主步行速度与最大步行速度、峰值握力、峰值膝伸力矩、全身体动偏移幅度以及最大功能性伸手距离。
研究结果：在对年龄和/或性别进行数据校正后，下肢机能（步行速度与膝伸力矩）与每日步数、每日超过3METs的活动时长呈显著正相关，这一关联在75岁及以上人群中尤为明显。另一方面，握力与全身体动偏移幅度与计步器/加速度计的测量结果无显著关联。线性与指数回归分析显示，在本研究观测到的最大值（每日13700步、每日超过3METs的活动时长62分钟）范围内，步行速度与计步器/加速度计评分呈正相关。然而，当将数据按四分位数分组后，每日步数超过7000~8000步、和/或每日超过3METs的活动时长超过15~20分钟的人群，其步行速度并未显著更高。除少数例外情况外，达到上述日常活动水平的受试者，其步行速度均高于预测功能依赖发生的临界值。
研究结论：本研究数据表明，每日步数超过7000~8000步、和/或每日进行超过15~20分钟的3METs以上强度活动的老年人，其身体机能维持良好。不过，这一关联的因果方向仍需通过纵向前瞻性研究和/或随机对照试验进一步探究。