In recent years international research on Sedentary Behaviour (SB) has
increased dramatically and there is growing evidence (see below) that
a multitude of serious health risks may be connected to "prolonged" and "excessive" sitting.
Sedentary Behaviour science is still emerging, however the evidence
to date is compelling. A variety of studies warn that sedentary
lifestyles are likely to be causing as many deaths as smoking.
Please check our complete research index. We make reference to evidence
listed in the Expert Statement(BLUE) and supplementary research studies
(RED).
Below you will find our Top 10 Risks. These risks typically grow the higher your "Sitting Calculator"
but more significantly for those sitting above 8 - 10 hours per day.
"Click to Expand"
[Note] All research references are indexed and can be found in the
Research links section.
There is evidence for an association between greater sedentary behaviour and an increased
risk of cardiovascular disease among adults, school-children and youth (32, 37, 38, 71, 74,
and 19). Two hours per day of screen time and sitting time were linked with a 5% and 17%
increased risk of cardiovascular events, respectively (72).
Increases in sedentary behaviour have been associated with increases in blood pressure among
children, teenagers and adults (87, 88, 74).
Interrupting sitting time has been associated with improved vascular function in young girls
and with improved endothelial function among adults (112, 113)
Both light intensity and moderate-to-vigorous physical activity breaks, but not standing,
might reduce inflammatory responses in adults (102).
Pulmonary embolism is a common cause of cardiovascular morbidity and mortality and
it is typically a consequence of a deep vein thrombosis in the lower extremities.
Risk factors for deep vein thrombosis/pulmonary embolism include age,
limb immobilisation, malignancy, pregnancy, surgery, and acquired or inherited
thrombophilia (90).
Physical inactivity has been associated with incident pulmonary embolism in women (90),
while prolonged work- and computer-related seated immobility was associated with an
increased risk of venous thromboembolism (89, 91, 92).
Regarding older adults, although there might be an association between overall sitting
and TV viewing and a higher risk of blood pressure, the evidence is still inconclusive (81).
Sedentary behaviour has been associated with an increased risk of cancer (37), endometrial cancer (34),
colon cancer (80) and breast cancer (79)
Although both body-mass index (BMI) and physical activity might be attenuating the link between
sedentary behaviour and some types of cancer, researchers still suggested adults (aged 50-71)
who watched TV for at least 7 hours a day had a 22% increased risk of cancer mortality relative
to those who watched TV less than one hour a day (40, 77).
It has been suggested that an important underlying mechanism by which sitting increases
cancer risk is adiposity (excess body weight) which might facilitate carcinogenesis
through insulin resistance, chronic inflammation, increased level of sex hormones and
altered secretion of adipokines (76).
Regarding older adults, the data on the association between sitting and cancer
remains insufficient (81).
A positive association between sedentary behaviour and type 2 diabetes has been reported
among adults, independent of physical activity (37, 74). People who watched TV for more
than 2 hours a day had a 20% increased risk of type 2 diabetes (38).
Regularly interrupting sitting with activity bouts of slightly more than one minute
every 30 minutes of sitting might be more effective than a single 30 minute walking
in lowering postprandial glucose and insulin levels (103).
Light-intensity physical activity breaks, but not standing, was associated with
significant reductions in postprandial (after meal) blood glucose and insulin levels (102).
In 2015 researchers found a positive association between sitting and body
composition, heart fat, liver fat, visceral fat, and waist circumference
independent of physical activity (7, 69). Interruptions of sitting
time with standing and stepping were associated with lower BMI scores
and waist circumference (95), but the evidence remains unclear (102).
Researchers suggested that watching TV might lead to obesity among
children and teenagers. However, factors such as unhealthy eating
and physical inactivity might contribute to this association (74).
Among adults, there is limited evidence for a longitudinal
relationship between sedentary behaviour, weight gain and obesity risk (77, 32, 78).
There is currently weak evidence for an association between sitting
and obesity and waist circumference among older adults (81).
Metabolic syndrome has been defined as central obesity (waist circumference) plus
any two of the following four risk factors: raised blood pressure, raised
triglycerides, reduced high density lipoprotein (HDL) cholesterol and raised
fasting plasma glucose.
Approximately 25% of European, American and Canadian adults have metabolic syndrome (73).
Men and women who sit more might have up to a 73%-76% increased risk of developing
metabolic syndrome compared with those who sit little, regardless of activity
and cardiorespiratory fitness (68). A similar association has been reported
for children and youth (71, 74).
Being physically active might reduce the risk (70). Among older adults (over 60 years old),
each hour of TV watching has been associated with a 19% increased risk of having metabolic
syndrome (81).
High amounts of sitting might be associated with a higher risk of psychological distress (43).
Similarly, among overweight/obese adults, decreasing sedentary time and increasing
moderate-to-vigorous-intensity physical activity were associated with a reduced
risk of depression (114).
Inactive mid-aged women who sat more than 7 hours a day were three times as likely to have
depressive symptoms compared with women who sat up to 4 hours a day AND were physically active (98).
Screen time has also been associated with a higher risk of depression when exceeding 2 hours/day and
a lower risk when screen time was less than 2 hours a day among children and adolescents (115).
A 31% increased risk for developing a mental disorder has been linked to adults who engage in
42 hours of watching TV and/or using the computer per week when compared with
those who do so for less than 10.5 hours per week (93).
Relative to those who were sedentary (4 hours or more/day), older adults who were moderately (2–4 hours/day)
and least sedentary (<2 hours/day) were 38% and 43% more likely to age successfully, respectively (50).
Less convincing evidence is available for the association between sedentary behaviour and anxiety.
However, moderate evidence suggests a link between total sitting and a greater risk of anxiety (96)
Although there seems to be a positive association between sitting and depressive symptoms
in children, teenagers and adults, the evidence remains inconclusive (74, 86).
The type and context of the sedentary behaviour is important, as activities such as computer use,
reading, playing board games and craft activities might be associated with a reduced risk of
dementia among older adults (over 60 years old) (81).
In terms of occupational health, lower back pain is the number one cause of
disability and one of the major risk factors for absenteeism (61).
Sitting time has been positively associated with both low back pain
and neck-shoulder pain intensity among blue-collar workers (101, 116).
When asked to interrupt their sitting at work every 30 min during the day,
overweight/obese office workers showed a 32% reduction in lower back discomfort,
compared to seated work (13).
However, there is currently insufficient evidence for a link between occupational
and screen-based sitting and musculoskeletal pain, independently of other factors,
among both children and adults (61, 74).
Age-related declines in muscle mass and strength (sarcopenia) often have a
negative impact on the independence of the elderly, increasing their risk of falling.
When sedentary our locomotor muscles are inactive most of the day.
Older adults watching TV at least 6 hours a day might have poorer
grip strength compared to those who engage in less than 2 hours of TV watching a day (44).
Stair climbing, for example, results in greater muscle activity than
brisk walking, as do standing and walking compared with sitting (45).
Weight bearing activities such as standing, walking and running stimulate
hip and lower body bones to grow thicker denser and stronger. Scientists
partly attribute the recent surge in cases of osteoporosis to lack of activity.
Osteoporosis is particularly important in the context of an ageing population.
Prolonged sitting might be a risk factor for bone health in women, even in
those who are physically active. How sedentary time is accumulated might also
be important: the longer (rather than the more frequent) the sitting bouts,
the higher their deleterious effects on bone mineral density (BMD) (51).
Some specific sedentary activities (screen-based) are negatively associated
with bone health in youth. This relationship between screen-based time and
bone health is independent of the total amount of physical activity,
but not independent of the frequency of muscle strengthening and
vigorous activities. Frequent, short bouts of such activities
(muscle strengthening and vigorous activity) interspaced with periods
of sedentary behaviours appear to be beneficial (118).
Sedentary behaviour has been associated with an increased risk of all-cause mortality
of up to 24%-49% (36, 37).
Whether physical activity attenuates the relationship, it remains unclear (105, 121).
The risk of all-cause mortality might be lowest in standing/walking occupations, especially among women (106).
Both maintaining sitting time low and reducing it was associated with a reduced
risk of all-cause mortality in American post-menopausal women (108).
Increasing standing time among Australians aged 45 and above seemed
to lower the risk of all-cause mortality (110, 111).
Watching TV for more than 2 hours per day was associated with a 13% increased risk (38).
The association between sitting and all-cause mortality among older adults (over 60 years old)
has also been supported by evidence (81).
Replacing one hour of sitting with low exercise activities such as household chores,
garden work and daily walking were sufficient to reduce all-cause mortality by 30%.
Exercise reduced the same risk by 48% (119).
Replacing sedentary time with equal amounts of sleeping (in people who sleep
less than 7 hours/day) and standing had beneficial effects (120).
