Higher levels of physical activity -- regardless of intensity -- are associated with a lower risk of early death in middle-aged and older people, a study claims. The findings, published in the British Medical Journal (BMJ), also show that being sedentary, for example sitting for 9.5 hours or more a day -- excluding sleeping time -- is associated with an increased risk of death.
However, these are based mainly on self-reported activity, which is often imprecise. So exactly how much activity -- and at what intensity -- is needed to protect health remains unclear.
Researchers led by Professor Ulf Ekelund at the Norwegian School of Sport Sciences in Oslo, Norway analysed observational studies assessing physical activity and sedentary time with death.
Studies included in the research used accelerometers -- a wearable device that tracks the volume and intensity of activity during waking hours -- to objectively measure daily activity levels.
Data from eight high quality studies involved 36,383 adults aged at least 40 years with average age of 62.
Activity levels were categorised into quarters, from least to most active, and participants were tracked for an average of 5.8 years.
"Another important finding was that spending 9.5 hours or more each day sedentary -- which essentially means sitting was associated with a statistically significant increased risk of death, with each hour more above this threshold increasing the risk of death further.
"This highlights the importance of avoiding spending most of the day sitting, as well undertaking purposeful physical activity," said Yates.
The researchers point to some limitations. For example, all studies were conducted in the US and western Europe, and included adults who were at least 40 years old, so findings may not apply to other populations or to younger people.
