What is the problem and what is known about it so far?

Spending more of our waking hours sedentary (for example, sitting and watching television) is associated with poorer markers of health and higher risk for death than spending more time engaged in physical activity (such as walking or playing sports). However, studies showing this increased risk for death have mostly relied on study participants' memories of how much time they spent sitting rather than on direct measures of that time. In addition, whether it matters if the total sedentary time is accumulated in shorter or longer bouts (that is, sitting for hours at a time without moving) is not known.

Why did the researchers do this particular study?

To assess the association of total sedentary time and longer and shorter bouts of sedentary time with mortality using an objective measurement tool.

Who was studied?

7985 black and white adults aged 45 years or older.

How was the study done?

The study participants were asked to wear devices that measure physical activity (accelerometers) for 7 days. The researchers also collected information on the participants' health-related characteristics, such as whether they smoked and had certain diseases like high blood pressure. They then followed the participants for years to see whether the total amount and patterns of sedentary time differed between those who did and those who did not die.

What did the researchers find?

Participants who spent more of their waking hours sedentary had an increased risk for death during the years of follow-up. In addition, longer bouts of sedentary time were associated with a higher risk for death than were shorter bouts of sedentary time. Shorter bouts of sedentary time (less than 30 minutes) were associated with less of an increase in risk than were longer bouts.

What were the limitations of the study?

The 7-day activity measurements and other health-related variables were collected early in the study and may have changed over the years of follow-up. Also, this study cannot prove that changing one's sedentary time or its pattern will reduce the risk for death.

What are the implications of the study?

The results suggest that spending less of our waking time being sedentary would be beneficial, and although no duration of sedentary time is good for you, shorter bouts seem to be associated with less risk.

中文翻译：

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久坐不动的持续时间与死亡风险有关

问题是什么？到目前为止我们知道什么？

与花更多时间从事体育活动（例如步行或运动）相比，将更多醒着时间久坐不动（例如，坐着看电视）与更差的健康指标和更高的死亡风险相关。然而，显示死亡风险增加的研究主要依赖于研究参与者对他们坐了多少时间的记忆，而不是直接测量那个时间。此外，不知道总久坐时间是在更短或更长的回合中累积（即一次坐几个小时不动）是否重要。

研究人员为什么要进行这项特殊研究？

使用客观测量工具评估总久坐时间和久坐时间的长短与死亡率之间的关系。

研究了谁？

7985 名 45 岁或以上的黑人和白人成年人。

研究是如何进行的？

研究参与者被要求佩戴测量身体活动的设备（加速度计）7天。研究人员还收集了参与者与健康相关的特征信息，例如他们是否吸烟以及是否患有高血压等某些疾病。然后，他们跟踪参与者多年，看看久坐时间的总量和模式在久坐的人和没有死的人之间是否存在差异。

研究人员发现了什么？

在后续的几年中，那些在醒着的时间里久坐不动的参与者死亡风险增加。此外，与较短的久坐时间相比，较长的久坐时间与较高的死亡风险相关。与久坐时间相比，较短的久坐时间（少于 30 分钟）与风险增加的相关性较小。

该研究的局限性是什么？

7 天活动测量值和其他与健康相关的变量是在研究早期收集的，并且可能在多年的随访中发生了变化。此外，这项研究不能证明改变一个人的久坐时间或其模式会降低死亡风险。

这项研究的意义是什么？

结果表明，减少我们醒着的时间久坐是有益的，尽管久坐不动的时间对你没有好处，但更短的时间似乎与更少的风险有关。