|
Regular exercise doesn't erase the higher risk of
serious illness that comes from sitting too much
each day, a new review reveals. The study –
published in the Annals of Internal Medicine – found
the amount of time a person sits during the day is
associated with a higher risk of heart disease,
diabetes, cancer, and death, regardless of regular
exercise.
"More than one half of an average person's day is
spent being sedentary—sitting, watching television,
or working at a computer," says Dr. David Alter,
Senior Scientist, Toronto Rehab, University Health
Network (UHN), and Institute for Clinical Evaluative
Sciences.
"Our study finds that despite the health-enhancing
benefits of physical activity, this alone may not be
enough to reduce the risk for disease."
I
The meta-analysis study reviewed studies focused on
sedentary behaviour. Forty-seven articles met
eligibility criteria. Meta-analyses were performed
on outcomes for cardiovascular disease and diabetes
(14 studies), cancer (14 studies), and all-cause
mortality (13 studies). Prospective cohort designs
were used in all but 3 studies; sedentary times were
quantified using self-report in all but 1 study.
Prolonged sedentary time was independently
associated with deleterious health outcomes
regardless of physical activity.
The lead author is Avi Biswas, PhD candidate,
Toronto Rehab, UHN and the Institute of Health
Policy, Management and Evaluation, University of
Toronto, and the senior author is Dr. Alter, who is
also Associate Professor of Medicine, University of
Toronto.
The researchers also found that the negative health
effects of prolonged sitting are more obvious among
those who do little or no exercise than those who do
more exercise.
The research is published Jan. 19 in the online
issue of Annals of Internal Medicine.
Among the studies reviewed by Biswas and his team,
the definition of prolonged sitting ranged from
eight hours a day to 12 hours or more.
Sitting, or sedentary activities ubiquitous with
sitting such as driving, using the computer or
watching TV, shouldn't comprise more than four to
five hours of a person's day, Biswas said, citing
guidelines issued by Public Health Agency of Canada.
"Exercise is just one hour in our day, if we're
diligent; we need to do something when we're not
otherwise exercising, like finding excuses to move
around, take the stairs or something else.
The biggest health hazard stemming from prolonged
sitting, according to the review, was a 90 percent
higher risk of developing type 2 diabetes. Among
studies examining cancer incidence and deaths,
significant links were specifically noted between
sedentary behavior and breast, colon, uterine and
ovarian cancers.
Future research will help determine what people can
do, in addition to physical activity, to combat the
health risks of sedentary time.
"Avoiding sedentary time and getting regular
exercise are both important for improving your
health and survival," says Dr. Alter.
Dr. Alter says people should aim to decrease
sedentary time by two to three hours in a 12-hour
day.
How to get started
Dr. Alter has a few steps people can take to reduce
sitting time:
Monitor sitting times—once we start counting, we're
more likely to change our behaviour.
Set achievable goals – find opportunities to
incorporate greater physical activity—and less time
sitting— into your daily life. For example, at work,
stand up or move for one to three minutes every half
hour; and when watching television, stand or
exercise during commercials.
Video:
http://www.ctvnews.ca/video?clipId=534317&playlistId=1.2196082&binId=1.810401&playlistPageNum=1&binPageNum=1
For more information
Annals of Internal Medicine
Sedentary Time and Its Association With Risk for
Disease Incidence, Mortality, and Hospitalization in
Adults: A Systematic Review and Meta-analysis
Medical Research Council
MDN |