Physical activity at any intensity linked to lower risk of early death – study
Sitting less and moving more often is associated with a lower risk of early death in middle aged and older people, according to scientists.
A new study, featured in the BMJ, shows that sitting for nine and a half hours or more a day, excluding sleeping time, is associated with an increased risk of death.
Previous studies have repeatedly suggested that sedentary behaviour is bad and physical activity is good for health and long life.
Researchers led by Professor Ulf Ekelund at the Norwegian School of Sport Sciences in Oslo explored this further by analysing observational studies assessing physical activity and sedentary time with death.
Studies used accelerometers, a wearable device that tracks the volume and intensity of activity during waking hours, to measure total activity in counts per minute (cpm) of wear time.
Intensity is usually separated into light, moderate and vigorous and the time in these intensities is then estimated.
Examples of light intensity activity includes walking slowly or light tasks such as cooking or washing dishes.
Moderate activity includes brisk walking, vacuuming or mowing the lawn, while vigorous activity includes jogging, carrying heavy loads or digging.
Data from eight high quality studies involving 36,383 adults aged at least 40 years (average age 62) were included.
Activity levels were categorised into quarters, from least to most active, and participants were tracked for an average of 5.8 years.
During follow-up, 2149 (5.9%) participants died.
After adjusting for potentially influential factors, the researchers found that any level of physical activity, regardless of intensity, was associated with a substantially lower risk of death.
Deaths fell steeply as total activity increased up to a plateau at 300cpm.
A similarly steep decrease in deaths occurred with increasing duration of light physical activity up to a plateau of about 300 minutes (five hours) per day and of moderate intensity physical activity of about 24 minutes per day.
The largest reduction in risk of death (about 60-70%) was between the first quarter (least active) and the fourth quarter (most active), with approximately five times more deaths in those being inactive compared with those most active.
The researchers say this strengthens the view that any physical activity is beneficial and likely achievable for large segments of the population.
In contrast, spending nine and a half hours or more each day sedentary was associated with a statistically significant increased risk of death.
The researchers point out that 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.
But they say the large sample size and device based measures of sedentary time and physical activity provide more precise results than previous studies.
Researchers say their results provide important data for informing public health recommendations, and suggest that the public health message might simply be “sit less and move more and more often”.