September 11, 2017

expert reaction to study investigating sedentary behaviour and mortality

Publishing in Annals of Internal Medicine, researchers looked at sedentary behaviour and reported that increased sedentary behaviour, both in total volume and prolonged uninterrupted bouts, was associated with increased risk of death.

Dr Amitava Banerjee, Senior Clinical Lecturer in Clinical Data Science and Honorary Consultant Cardiologist, UCL, said:

“This large-scale US study in nearly 8000 individuals over the age of 45 years measured physical activity using accelerometers which is much more objective than self-report. There were three main findings. First, inactivity or “sedentary behaviour” made up most of the waking day: 12.3 out of 16 hours. Second, the total time spent inactive as well as the average duration of each period of inactivity were both associated with a higher risk of all-cause mortality. Third, the increased risk of mortality associated with sedentary behaviour was lower in those individuals who kept sedentary periods to less than 30 minutes.

“This is an observational study and does not show causation. It should be noted that the accelerometer was only worn for 7 days and could not distinguish between sitting and standing and so classification of “sedentary” is not strictly speaking, correct. The 7 days of observed activity may not be a representative of long-term pattern of activity. The authors controlled for age, sex, race, body-mass index, exercise habits and common cardiovascular risk factors such as diabetes. Although the study was in middle-aged and older individuals, the recommendation for all people should be to stay active as often as possible and for longer periods of time. Conversely, periods of sedentary behaviour should be kept to a minimum, aiming for below 30 minutes.”

* ‘Patterns of Sedentary Behavior and Mortality in U.S. Middle-Aged and Older Adults’ by Diaz et al. published in Annals of Internal Medicine on Monday 11 September. 

Declared interests

Dr Amitava Banerjee: No conflicts of interest.