Department of Public Health and Primary Care, University of Cambridge School of Clinical Medicine, Cambridge, United Kingdom.
MRC Epidemiology Unit, University of Cambridge, School of Clinical Medicine, Cambridge, United Kingdom.
PLoS One. 2019 Oct 25;14(10):e0224225. doi: 10.1371/journal.pone.0224225. eCollection 2019.
Compensatory behaviours may be one of the reasons for the limited success of sedentary time interventions in older adults, but this possibility remains unexplored. Activity compensation is the idea that if we change activity levels at one time we compensate for them at a later time to maintain a set point. We aimed to assess, among adults aged ≥60 years, whether sedentary time and time spent in prolonged sedentary bouts (≥30 mins) on one day were associated with sedentary time and time spent in prolonged sedentary bouts (≥30 mins) on the following day. We also sought to determine whether these associations varied by sociodemographic and comorbid factors.
Sedentary time was assessed for seven days using hip-worn accelerometers (ActiGraph GT1M) for 3459 adults who participated in the EPIC-Norfolk Study between 2004 and 2011. We assessed day-to-day associations in total and prolonged bouts of sedentary time using multi-level regressions. We included interaction terms to determine whether associations varied by age, sex, smoking, body mass index, social class, retirement, education and comorbid factors (stroke, diabetes, myocardial infarction and cancer).
Participants (mean age = 70.3, SD = 6.8 years) accumulated 540 sedentary mins/day (SD = 80.1). On any given day, every 60 minutes spent in sedentary time was associated with 9.9 extra sedentary minutes on the following day (95% CI 9.0, 10.2). This association was greater in non-retired compared to retired participants (non-retired 2.57 extra minutes, p = 0.024) and in current compared to former and never-smokers (5.26 extra mins for current vs former; 5.52 extra mins for current vs never, p = 0.023 and 0.017, respectively). On any given day, every 60 minutes spent in prolonged bouts was associated with 7.8 extra minutes in these bouts the following day (95% CI 7.6, 8.4). This association was greater in older individuals (0.18 extra minutes/year of age, 95% CI 0.061, 0.29), and for retired versus non-retired (retired 2.74 extra minutes, 95% CI 0.21, 5.74).
Older adults did not display day-to-day compensation. Instead, individuals demonstrate a large stable component of day-to-day time spent sedentary and in prolonged bouts with a small but important capacity for positive variation. Therefore older adults appear to be largely habitual in their sedentary behaviour. Strategies to augment these patterns may be possible, given they may differ by age, smoking, and working status.
补偿行为可能是导致老年人久坐时间干预效果有限的原因之一，但这一可能性仍未得到探索。活动补偿是指如果我们改变一个时间的活动水平，我们会在稍后的时间进行补偿，以维持一个设定点。我们旨在评估年龄在 60 岁及以上的成年人中，一天内的久坐时间和长时间久坐（≥30 分钟）与第二天的久坐时间和长时间久坐（≥30 分钟）之间是否存在关联。我们还试图确定这些关联是否因社会人口统计学和合并症因素而有所不同。
2004 年至 2011 年间，3459 名参与 EPIC-Norfolk 研究的成年人使用 Hip-worn 加速度计（ActiGraph GT1M）评估了七天的久坐时间。我们使用多层次回归评估了总久坐时间和长时间久坐时间的日常关联。我们包括了交互项，以确定关联是否因年龄、性别、吸烟、体重指数、社会阶层、退休、教育和合并症（中风、糖尿病、心肌梗死和癌症）而有所不同。
参与者（平均年龄=70.3 岁，标准差=6.8 岁）每天积累 540 分钟的久坐时间（标准差=80.1）。在任何一天，每增加 60 分钟的久坐时间，第二天就会额外增加 9.9 分钟的久坐时间（95%置信区间 9.0，10.2）。与退休参与者相比，非退休参与者的这种关联更大（非退休者额外 2.57 分钟，p=0.024），与前吸烟者和从不吸烟者相比，当前吸烟者的关联更大（当前吸烟者比前吸烟者多 5.26 分钟；当前吸烟者比从不吸烟者多 5.52 分钟，p=0.023 和 0.017）。在任何一天，每增加 60 分钟的长时间久坐时间，第二天的长时间久坐时间就会额外增加 7.8 分钟（95%置信区间 7.6，8.4）。这种关联在年龄较大的个体中更大（每增加 1 岁，额外 0.18 分钟，95%置信区间 0.061，0.29），以及退休与非退休者相比（退休者额外 2.74 分钟，95%置信区间 0.21，5.74）。
老年人没有表现出日常补偿。相反，个体表现出很大的稳定的日常久坐时间和长时间久坐时间的组成部分，只有很小但重要的积极变化的能力。因此，老年人的久坐行为似乎在很大程度上是习惯性的。鉴于这些模式可能因年龄、吸烟和工作状态而异，改变这些模式的策略可能是可行的。
