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Sedentary Lifestyle: Overview of
Updated Evidence of Potential Health
Risks
Jung Ha Park1, Ji Hyun Moon1,2, Hyeon Ju Kim1,2, Mi Hee Kong1,2, Yun Hwan Oh1,2,*
1Department of Family Medicine, Jeju National University Hospital, Jeju, Korea
2Department of Family Medicine, Jeju National University School of Medicine, Jeju, Korea
One-third of the global population aged 15 years and older engages in insufficient physical activities, which affects
health. However, the health risks posed by sedentary behaviors are not well known. The mean daily duration of
sedentary behavior is 8.3 hours among the Korean population and 7.7 hours among the American adult popula-
tion. Sedentary lifestyles are spreading worldwide because of a lack of available spaces for exercise, increased occu-
pational sedentary behaviors such as office work, and the increased penetration of television and video devices.
Consequently, the associated health problems are on the rise. A sedentary lifestyle affects the human body through
various mechanisms. Sedentary behaviors reduce lipoprotein lipase activity, muscle glucose, protein transporter
activities, impair lipid metabolism, and diminish carbohydrate metabolism. Furthermore, it decreases cardiac out-
put and systemic blood flow while activating the sympathetic nervous system, ultimately reducing insulin sensitivi-
ty and vascular function. It also alters the insulin-like growth factor axis and the circulation levels of sex hormones,
which elevates the incidence of hormone-related cancers. Increased sedentary time impairs the gravitostat, the
body’s weight homeostat, and weight gain, adiposity, and elevated chronic inflammation caused by sedentary be-
havior are risk factors for cancer. Sedentary behaviors have wide-ranging adverse impacts on the human body in-
cluding increased all-cause mortality, cardiovascular disease mortality, cancer risk, and risks of metabolic disor-
ders such as diabetes mellitus, hypertension, and dyslipidemia; musculoskeletal disorders such as arthralgia and
osteoporosis; depression; and, cognitive impairment. Therefore, reducing sedentary behaviors and increasing
physical activity are both important to promote public health.
Keywords: Sedentary Behavior; All-Cause Mortality; Cancer; Metabolic Disease; Physical Activity; Exercise
Received: July 15, 2020, Accepted: August 4, 2020
*Corresponding Author: Yun Hwan Oh https://orcid.org/0000-0002-1627-7528
Tel: +82-64-717-8650, Fax: +82-64-757-8276, E-mail: swimayo@gmail.com
https://doi.org/10.4082/kjfm.20.0165 • Korean J Fam Med 2020;41:365-373
Review Article
eISSN: 2092-6715
Copyright © 2020 The Korean Academy of Family Medicine
This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0)
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Jung Ha Park, et al. • Sedentary Lifestyle: Overview of Updated Evidence of Potential Health Risks366
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https://doi.org/10.4082/kjfm.20.0165
INTRODUCTION
1. Epidemiology
Approximately 31% of the global population aged ≥15 years engages in
insufficient physical activity, and it is known to contribute to the death
of approximately 3.2 million people every year.1) In South Korea, the
physical activity rate is on the decline among adults aged ≥19 years, ir-
respective of the type of activity, including aerobic exercise, walking,
and muscle training. Therefore, in 2017, the rates of aerobic exercise,
walking, and muscle training in the Korean adult population were
48.5%, 39.0%, and 21.6%, respectively, with the majority of the Korean
population engaging in physical inactivity.2) In addition to physical in-
activity, sedentary behavior is also a serious problem, and a substantial
number of people engage in it for prolonged periods. For instance,
Americans spend 55% of their waking time (7.7 hours a day) engaged
in sedentary behaviors whereas Europeans spend 40% of their leisure
time (2.7 hours a day) watching television.3) Similar patterns have been
observed in Koreans, who have been reported to demonstrate long
sedentary times. According to Korea Health Statistics of 2018, adults in
Korea aged ≥19 years engage in 8.3 hours of sedentary time. Only 8.9%
of the adult population engaged in <4 hours of sedentary time whereas
20.6% of the adults were involved in >12 hours of sedentary time.4)
2. Causes of Physical Inactivity and Sedentary Lifestyles
A poor participation in physical activity is speculated to be influenced
by multiple factors. Some environmental factors include traffic con-
gestion, air pollution, shortage of parks or pedestrian walkways, and a
lack of sports or leisure facilities.1) Television viewing, video viewing,
and cell phone usage are positively correlated with an increasingly
sedentary lifestyle.5) Sedentary behaviors are projected to continue to
rise on the basis of this socio-cultural background.
Sedentary lifestyles have a major impact on the overall health of the
global population. Many people worldwide engage in sedentary life-
styles, and the prevalence of relevant non-communicable diseases is
on the rise. It is well known that insufficient physical activity, that is,
physical inactivity, has a detrimental effect on health. Physical inactivi-
ty is the fourth leading risk factor for global mortality, accounting for
6% of global mortality.6) Despite the fact that sedentary behavior poses
a comparable risk to health and contributes to the prevalence of vari-
ous diseases, most physical activity-related education in clinical prac-
tice is focused on improving the physical activity levels, with less em-
phasis on lowering the sedentary behavior. In addition to understand-
ing and informing patients about the health impact of a sedentary life-
style, healthcare providers of various fields, including clinicians,
should reflect upon its significance in policies. This study examined
the effects of a sedentary lifestyle on health and the lifestyle-related
improvements to be made to promote healthy living.
OVERVIEW OF SEDENTARY LIFESTYLE
1. The Concept of a Sedentary Lifestyle
Sedentary behavior is defined as any waking behavior such as sitting
or leaning with an energy expenditure of 1.5 metabolic equivalent task
(MET) or less.7) This definition, proposed by the Sedentary Behavior
Research Network in 2012, is currently the most widely used definition
of sedentary behavior. Some examples of sedentary behavior include
television viewing, playing video games, using a computer, sitting at
school or work, and sitting while commuting (Figure 1).8) According to
the 2011 Compendium of Physical Activities, MET is defined as the ra-
tio of work metabolic rate to the standard resting metabolic rate (RMR)
A B
C D
Figure 1. Examples of sedentary behavior. (A)
Playing a video game. (B) Watching television.
(C) Using a computer. (D) Reading a book.
Jung Ha Park, et al. • Sedentary Lifestyle: Overview of Updated Evidence of Potential Health Risks
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of 1 kcal/(kg/h). One MET is the RMR or energy cost for a person at
rest. When classified quantitatively based on their intensities, physical
activities can be classified into 1.0–1.5 METs (sedentary behavior), 1.6–
2.9 METs (light intensity), 3–5.9 (moderate intensity), and ≥6 METs
(vigorous intensity) (Figure 2).9)
A sedentary lifestyle increases all-cause mortality and the risks for
cardiovascular diseases (CVD), diabetes mellitus (DM), hypertension
(HTN), and cancers (breast, colon, colorectal, endometrial, and epi-
thelial ovarian cancer). This has been consistently documented in the
literature.3,10,11) There is no disagreement on the fact that prolonged to-
tal sedentary behavior times are associated with poor disease out-
comes. However, the patterns of sedentary time may differ even within
the same total amount of time, and not much is known about the par-
ticular patterns of prolonged sedentary time that pose more significant
health hazards (for example, continuous sedentary behavior without a
break or intermittent sedentary behavior).12) One study reported that
even if the total sedentary time was equal, having short sedentary
bouts and engaging in physical activities intermittently can have rela-
tive health benefits. The total sedentary time and moderate-to-vigor-
ous physical activity (MVPA) have been reported to be negatively cor-
related, where the waist circumference (standardized β, -0.16; 95%
confidence interval [CI], -0.31 to -0.02; P=0.026), body mass index (β,
-0.19; 95% CI, -0.35 to -0.02; P=0.026), triglyceride level (β, -0.18; 95%
CI, -0.34 to -0.02; P=0.029), and 2-hour postprandial plasma glucose
level (β, -0.18; 95% CI, -0.34 to -0.02; P=0.025) decreased with increas-
ing the number of breaks in the sedentary time.13) Furthermore, when
the sedentary time was interrupted with light- or moderate-intensity
physical activity, the systolic and diastolic blood pressures dropped by
2–3 mm Hg whereas interrupting the sedentary time with light-inten-
sity physical activity (LIPA) or simple muscle training in patients with
diabetes (88% of the population had HTN) decreased the systolic pres-
sure by 14–16 mm Hg and the diastolic pressure by 8–10 mm Hg.14)
2. Physiological Features
The exact mechanisms of the various adverse effects of sedentary be-
havior on the human body are currently unknown. However, several
hypotheses have been proposed for the overall understanding of the
impact of sedentary behavior on the human body, which are de-
scribed below.
Sedentary lifestyles are associated with metabolic dysfunctions,
such as elevated plasma triglycerides and high-density lipoprotein
(HDL) cholesterol and reduced insulin sensitivity.15,16) Lipoprotein li-
pase (LPL) is a protein that interacts at the cellular level, and a low LPL
concentration is known to decrease the plasma HDL cholesterol level,
while affecting the prevalence of severe HTN, diabetes-induced dys-
lipidemia, metabolic disorders caused by aging, metabolic syndrome,
and coronary artery diseases. Moreover, LPL activity is diminished by
physical inactivity. Additionally, physical inactivity inhibits LPL activity
in skeletal muscles and rapidly signals for impaired lipid metabolism.
In an experiment based on a rat model, the reduction of LPL activity in
rats that engaged in light walking was only about 10% of the LPL activi-
ty in rats that were only placed in their cages.17) The fact that muscle
LPL activity is highly sensitive to physical inactivity and low-intensity
muscular contractile activity can serve as evidence supporting the the-
ory that sedentary behavior is a risk factor for various metabolic disor-
ders.18)
Physical inactivity reduces bone mineral density.19) In a study on
healthy adult men and women, 12 weeks of bed rest decreased the
mineral density of the lumbar spine, femoral neck, and greater tro-
chanter by 1%–4%.19) The balance between bone resorption and bone
deposition mediates the relationship between sedentary behavior and
the reduction of bone mineral density. According to some studies, bed
rest elevates bone resorption markers and does not influence bone
formation markers.20-22)
Some studies have provided limited evidence that sedentary behav-
ior has a negative impact on vascular health. A study on healthy wom-
en reported that 56 days of head-down bed rest decreased the endo-
thelium-dependent vasodilation while increasing the endothelial cell
damage. Such alterations in vascular function were prevented through
aerobic exercise and muscle training.23)
SEDENTARY LIFESTYLES AND HEALTH RISKS
1. Sedentary Lifestyles, Mortality, and Morbidity
(Cardiovascular Diseases and Other Causes)
A sedentary lifestyle is strongly associated with CVD, DM, cancer, and
premature mortality. The total daily sedentary time and television
viewing time were correlated with an increased all-cause mortality
risk.24) In a study analyzing the mortality rates of people with >10 hours
and <5 hours of sitting times a day, the sitting time was significantly
correlated with all-cause mortality (odds ratio [OR], 1.16; 95% CI, 1.04–
1.29; P<0.05).25) In a study that examined the correlation between the
television viewing time and all-cause mortality, the people who
watched television for ≥6 hours a day had a two-fold higher all-cause
mortality risk compared to the people who watched television for <2
hours a day (hazard ratio [HR], 1.98; 95% CI, 1.25–3.15)26) whereas the
people who watched television for ≥4 hours a day had a 1.5 times
higher all-cause mortality risk compared to the people who watched
TV for <2 hours a day (HR, 1.48; 95% CI, 1.19–1.83).27)
Figure 2. Examples of moderate to vigorous physical activity. (A) Riding a bicycle. (B)
Running.
A B
Jung Ha Park, et al. • Sedentary Lifestyle: Overview of Updated Evidence of Potential Health Risks368
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Sedentary time (sitting time, television or screen viewing time, lei-
sure time while sitting in a day) is independently associated with all-
cause mortality, CVD incidence or mortality, incidence or mortality of
certain cancers (breast, colon, colorectal, endometrial, and epithelial
ovarian cancer), and type 2 DM. In particular, the adverse effect of
sedentary time was more evident among people who engaged in little
physical activity compared to those who engaged in frequent physical
activity. The relative risk (RR) for all-cause mortality was 30% higher
with high physical activity (HR, 1.16; 95% CI, 0.84–1.59) compared to
that with low physical activity (HR, 1.46; 95% CI, 1.22–1.75).28)
2. Sedentary Lifestyles and Metabolic Diseases
1) Diabetes mellitus
The fact that the prevalence of type 2 DM increases with increasing
sedentary time has been consistently documented in various studies
(HR, 1.91; 95% CI, 1.64–2.22).28)
In an assessment of DM risk considering both sedentary time and
physical activity, the DM risk increased with the increasing daily sed-
entary time (HR, 1.13; 95% CI, 1.04–1.22; P<0.001), and the effect was
not offset by the level of physical activity (HR, 1.11; 95% CI, 1.01–1.19;
P<0.001). The risk for CVD also increased with the increasing daily
sedentary time (HR, 1.29; 95% CI, 1.27–1.30; P<0.001), and although
the physical activity level slightly offset this effect, sedentary time still
significantly increased the risk (HR, 1.11; 95% CI, 1.01–1.19; P<0.001).
This shows that the level of physical activity does not influence the im-
pact of prolonged sedentary time on the risk for CVD and DM.
A few biological mechanisms can explain the impact of the total
daily sedentary time on CVD and DM risk. Prolonged sitting is known
to affect the content and activity of muscle glucose transporter pro-
teins. An animal study observed that prolonged muscle inactivity re-
duces the LPL activity, which regulates blood lipid concentration and
carbohydrate metabolism through cellular pathways that differ from
the normal motor response; however, additional verification is re-
quired by human studies.29)
2) Hypertension
A sedentary lifestyle affects blood pressure through various mecha-
nisms, and subsequently changes the blood pressure by altering the
cardiac output and total peripheral vascular resistance. A prolonged
sedentary time reduces the metabolic demands and systemic blood
flow, and by stimulating the sympathetic nervous system, it decreases
insulin sensitivity and vascular function while increasing the oxidative
stress and promoting the low-grade inflammatory cascade.14) A study
reported a direct association between sedentary behavior and a high
risk of HTN (HR, 1.48; 95% CI, 1.01–2.18; P for trend=0.03). Among
sedentary behaviors, non-interactive sedentary behaviors (watching
television, sleeping) have been reported to further escalate the risk for
HTN compared to interactive sedentary behaviors (driving, using a
computer).30)
3) Dyslipidemia
Sedentary behaviors induce metabolic dysfunction characterized by
elevated blood triglyceride levels, reduced HDL-cholesterol levels, and
diminished insulin sensitivity.17) A study reported that sedentary be-
haviors increased the rate of newly diagnosed dyslipidemias in women
(OR, 1.17; 95% CI, 1.00–1.36) and increased the risk for dyslipidemia in
both men and women (men: OR, 1.21; 95% CI, 1.02–1.44) (women:
OR, 1.24; 95% CI, 1.04–1.48).31) In contrast, MVPA was negatively asso-
ciated with blood triglyceride levels (β, -0.18; 95% CI, -0.36 to -0.01;
P=0.038).32)
4) Obesity
Sedentary time is known to have significant correlations with waist cir-
cumference and clustered metabolic risk scores independent of
MVPA. The waist circumference increased by 3.1 cm with a 10% in-
crease in the sedentary time.32) Obese patients tend to move less;
therefore, increasing the activity levels can be utilized as a strategy in
obesity treatment.33) While this is a widely known fact, the underlying
mechanism remains unknown. A study in 2020 reported that the rea-
son for weight gain is a prolonged sedentary time.34) According to a
Swedish study that compared an experimental group which wore a
heavy 11-kg vest for 8 hours a day and the control group which wore a
light 1-kg vest for 8 hours a day, the experimental group had a weight
loss of 1.6 kg whereas the control group lost 0.3 kg three weeks later. An
animal study shed light on an energy balance system known as the
“gravitostat” that maintains a consistent body weight.35) This regulation
occurs partially due to an influence on appetite where the system re-
quires a personal weighing machine for the proper functioning of this
regulation. This Swedish study found that humans also feature a simi-
lar built-in scale. An individual’s scale measures lower values with pro-
longed sitting, which explains why sitting is associated with obesity
and poor health. A heavy vest can increase the score on this, thereby
inducing weight loss.34)
3. Sedentary Lifestyles and Cancer Risk
Sedentary behavior is also closely related to the prevalence of cancer.
According to a study that investigated the correlation between seden-
tary behavior and cancer prevalence, the cancer risk was 13% higher in
the group with the longest sedentary time compared to that with the
shortest sedentary time,28) and another study reported that sedentary
time increased the overall cancer risk by 20%.36)
Prolonged sitting increases colorectal, endometrial, ovarian, and
prostate cancer risks, and it has been reported to increase cancer mor-
tality particularly in women.37) There was a significant correlation be-
tween cancer mortality and the incidences of breast, colorectal, endo-
metrial, and epithelial ovarian cancers.28) An increased total sitting
time was positively correlated with colon cancer (RR, 1.24; 95% CI,
1.03–1.50) and endometrial cancer (RR, 1.32; 95% CI, 1.08–1.61).36) Ad-
ditionally, television viewing time was also positively correlated with
colon cancer (RR, 1.54; 95% CI, 1.19–1.98) and endometrial cancer
(RR, 1.66; 95% CI, 1.21–2.28).36) Occupational sitting time was positive-
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ly correlated with only colon cancer (RR, 1.24; 95% CI, 1.09–1.41).36)
Sedentary behavior leads to metabolic dysfunctions such as hyper-
glycemia, hyperinsulinemia, insulin resistance, perturbation of insu-
lin-like growth factor axis, and changes in the circulation levels of sex
hormones. Altered circulation levels of sex hormones can be linked to
hormone-related cancers such as breast and endometrial cancers.38)
Additionally, sedentary behavior induces low-grade chronic systemic
inflammation, and sedentary time is associated with inflammation-re-
lated markers such as C-reactive protein (β, 0.18±0.06; P=0.002), inter-
leukin 6 (β, 0.24±0.06; P<0.001), leptin (β, 0.15±0.04; P<0.001), and the
leptin: adiponectin ratio (β, 0.21±0.05; P<0.001).39) Chronic inflamma-
tion can trigger cancer growth.40) Adiposity can also mediate the rela-
tionship between sedentary behavior and cancer, and obesity is a risk
factor for several cancers.8)
4. Sedentary Lifestyles and Osteoporosis
Sedentary behavior is known to show a negative association with the
bone mineral density of the total femur and all hip sub-regions irre-
spective of MVPA, and the bone mineral density (g/cm2) of the total
femur had a marked negative correlation with the sedentary time (β,
-0.16; 95% CI, -0.24 to -0.08) in adult women.41) Bone mineral density
was correlated with the duration and not the frequency of sedentary
behavior. In men, sedentary behavior was not markedly correlated
with the bone mineral density of the hip and spine.41)
5. Sedentary Lifestyles and Musculoskeletal Diseases
A prolonged sedentary time was correlated with chronic knee pain. In
an analysis of the correlation between chronic knee pain and the total
daily sedentary time (<5, 5–7, 8–10, >10 hours), the results claimed that
the incidence of chronic knee pain was higher in individuals with lon-
ger sedentary times (P for trend=0.02).42) In particular, a sedentary time
>10 hours a day was markedly correlated with chronic knee pain (ad-
justed OR, 1.28; 95% CI, 1.02–1.61; P=0.03).42) People who engaged in
greater physical activity had less chronic knee pain (adjusted OR, 0.78;
95% CI, 0.67–0.91; P=0.00), but women with >10 hours of sedentary
time while engaging in greater physical activity were highly likely to
experience chronic knee pain (adjusted OR, 1.19; 95% CI, 1.02–1.39;
P=0.03). The study recommends individuals to shorten their sedentary
times to <10 hours a day.42)
6. Sedentary Lifestyles and Other Diseases
1) Depression
Mentally passive sedentary behaviors such as television viewing (RR,
1.18; 95% CI, 1.07–1.30), sitting, listening to music, and talking while
sitting were positively correlated with depression risks (RR, 1.17; 95%
CI, 1.08–1.27). In contrast, mentally active sedentary behaviors such as
reading books or newspapers, driving, attending a meeting, or knitting
or sewing were not markedly correlated with depression risk (RR, 0.98;
95% CI, 0.83–1.15).43) Using a computer, which is a mentally active sed-
entary behavior, was not correlated with depression risk in one study
(RR, 0.99; 95% CI, 0.79–1.23)43) but was positively correlated with de-
pression risk in another study (RR, 1.22; 95% CI, 1.10–1.34),44) and thus
its correlation with depression remains controversial. The mechanism
underlying the correlation between sedentary behavior and depres-
sion may involve the following: sedentary behaviors may increase the
risk for depression by blocking direct communication and lowering
social interactions, or by reducing the available time to engage in
physical activities that help to prevent and treat depression.43)
2) Cognitive function
The relationship between sedentary behavior and cognitive function
is uncertain. A systematic review found marked alterations of cogni-
tion (improved in two studies45,46) and impaired in two studies47,48)) in
some studies but no changes in cognitive function in some studies.49)
However, the only long-term study included in that systematic review
suggested that a less-sedentary lifestyle and less sedentary work have
benefits related to cognitive function.46) It is believed that replacing the
sedentary time with physical activity can help improve the cognitive
function. In a randomized clinical trial that analyzed the cognitive
changes after 30 minutes of sedentary behavior with other activities for
6 months in older adults with little physical activity, replacing the sed-
entary time with MVPA and sleep significantly improved cognitive
functions, and replacing it with LIPA did not lead to statistically signifi-
cant changes.46)
SEDENTARY LIFESTYLES AND PHYSICAL ACTIVITY
1. Discrepant Health Effects of Sedentary Lifestyle and
Physical Activity
Past studies have observed that a prolonged sedentary lifestyle leads to
poor health outcomes irrespective of physical activity. A sedentary life-
style was independently correlated with mortality and was not com-
pensated for by physical activity.10) The time spent in front of a screen
was positively correlated with the presence of metabolic syndrome, in-
dependent of the level of physical activity (OR, 3.30; 95% CI, 2.04–
5.34).50)
2. The Attenuative Effect of Physical Activity on Sedentary
Lifestyles
A few recent studies have reported that increasing physical activity can
offset the adverse impacts of sedentary behavior. In particular, the off-
set effect was more evident in people with little physical activity.
A meta-analysis reported that mortality was not elevated in the peo-
ple engaging in high levels of moderate-intensity physical activity (60–
75 minutes of moderate-intensity physical activity a day) even when
they had >8 hours of sedentary time a day. There was no difference in
mortality between the most active people (>35.5 MET-h/wk) with <4
hours of sedentary time a day and equally active people (>35.5 MET-
h/wk) with >8 hours of sedentary time a day (HR, 1.04; 95% CI, 0.99–
1.10). However, television viewing for >3 hours a day increased the
mortality regardless of physical activity, and the people who watched
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television for ≥5 hours a day showed markedly high mortalities (HR,
1.16; 95% CI, 1.05–1.28).51)
In one study, sitting time showed a dose-response with all-cause
mortality and CVD mortality risk in the least active group (<150 MVPA
min/wk).51) In contrast, the group with at least 8 hours of sedentary
time a day showed a higher mortality than the group with less than 4
hours of sedentary time a day (HR, 1.52; 95% CI, 1.13–2.03). However,
the group who met the essential MVPA criterion (150–299 MVPA min/
wk) or engaged in more physical activity did not show a consistent
trend in the relationship between increased sitting time and CVD and
all-cause mortalities.
Similarly, a study showed that a sedentary time of over 9 hours per
day in the low physical activity group (<600 METs-min/wk) had a sig-
nificant association with an increased CVD risk (OR, 1.29; 95% CI,
1.04–1.62). In the group with more physical activity, sedentary time
was not significantly associated with CVD risk.52)
In other words, while increased sedentary time increases the mor-
tality among people who engage in little physical activity, adequate
physical activity seems to offset the impact of increased sedentary time
on mortality.53)
A study analyzed the correlation between all-cause mortality and
net uncompensated sedentary behavior metabolic equivalent hours
(USMh=MET/h [sedentary time]–MET/h [MVPA time]), which was
computed by subtracting METs for MVPA from METs for sedentary
behavior throughout a day. USMh was independently associated with
all-cause mortality when it was greater than 7 MET/h, and for televi-
sion viewing, when it was greater than 3 MET/h. The mean increase in
mortality per USMh was 1% (RR, 1.01; 95% CI, 1.00–1.02; P=0.01), and
the mean increase in mortality per USMh for TV watching was 7% (RR,
1.07; 95% CI, 1.04–1.10; P<0.001). In other words, physical activity as
well as sedentary time should be assessed, and therefore, USMh was
revealed to be a more practical index for assessing sedentary behav-
ior.54)
In the people with the least daily activity (≤17 min/d MVPA), replac-
ing 30 minutes of the sitting time each day with light physical activity
reduced the mortality risk by 14% (HR, 0.86; 95% CI, 0.81–0.89), and
replacing it with MVPA reduced the mortality risk by 45% (HR, 0.55;
95% CI, 0.47–0.62). However, in the people with the highest daily activ-
ity (MVPA >38 min/d), replacing the sitting time with LIPA or MVPA
was not linked with a reduced mortality risk.55)
Replacing the sedentary behavior with physical activity also has an
impact on cancer-related mortality. A recently published study
showed that sedentary behavior was independently associated with
cancer mortality risk, where a higher sedentary time led to a greater
cancer mortality risk. In this study, the individuals in the top 1/3 of the
sedentary group showed a substantially higher cancer mortality risk
than those in the bottom 1/3 (adjusted HR, 1.52; 95% CI, 1.01–2.27).56)
However, replacing 30 minutes of sedentary time with LIPA reduced
the cancer mortality by 8% (HR, 0.92; 95% CI, 0.86–0.97) and replacing
it with MVPA reduced it by 31% (HR, 0.69; 95% CI, 0.48–0.97).56)
CLINICAL PEARLS FOR SEDENTARY INDIVIDUALS
While the various countries have their own guidelines for physical ac-
tivity and sedentary behavior, overall, the recommendations are simi-
la r.
1. Recommendations in the United States
Although the 2018 Advisory Committee revealed that sedentary be-
havior is strongly correlated with all-cause and CVD mortalities in
adults, the evidence was insufficient to offer advice on the recom-
mended daily sedentary time and duration of physical activity. It could
not determine the recommended daily sedentary time and frequency
of physical activity for adults or adolescents because the risks associat-
ed with sedentary behavior are related to the amount of MVPA.
It is advisable for inactive people not engaging in moderate physical
activity (MPA) to lower their sedentary behavior and replace their sed-
entary behavior with LIPA. However, LIPA alone is insufficient to ob-
tain health benefits; they will be able to reduce their health risk by
gradually increasing their physical activities to MPA or beyond. Inac-
tive people who engage in insufficient physical activity that does not
meet the criterion of 150–300 minutes of MPA per week would be able
to obtain health benefits by increasing their MPA slightly and reap
even greater health benefits by reducing their sedentary behaviors. Ac-
tive people who engage in sufficient physical activity (150–300 minutes
of MPA per week) would gain more benefits by lowering their seden-
tary behaviors. Highly active people who engage in more than 300
minutes of MPA per week are recommended to maintain or improve
their levels of physical activity by participating in a variety of activi-
ties.57)
2. Recommendations in Australia
The Australian Government Department of Health presented age-spe-
cific recommendations for physical activity and sedentary behavior.
According to the Australian physical activity-sedentary behavior
guidelines, individuals are recommended to minimize their sitting
times, including sitting during work, commuting, and breaks, and to
avoid sitting for prolonged periods as much as possible.58) Infants and
children aged less than 5 years are advised to not be bound in a stroller,
car seat, or high chair for more than 1 hour at a time. While they en-
gage in sedentary behaviors, they are recommended to spend time
reading books, singing, solving puzzles, and talking with their caregiv-
ers as compared to watching television or a DVD (digital video disc),
playing on the computer, or playing other video games.59) For children
between the ages of 5 and 17, the sedentary recreational screen time
should be limited to 2 hours a day, and they are advised to engage in
positive social interactions and experiences. Older adults aged 65
years and more are advised to remain active as much as possible every
day.60) The recommended amount of physical activity for adults is 150–
300 minutes of MPA or 75–150 minutes of vigorous physical activity or
an equivalent MVPA per week.
Jung Ha Park, et al. • Sedentary Lifestyle: Overview of Updated Evidence of Potential Health Risks
https://doi.org/10.4082/kjfm.20.0165
www.kjfm.or.kr 371
3. Recommendations in Korea
The guidelines for physical activity for the Korean population pub-
lished by the Department of Health Promotion at the Ministry of
Health and Welfare in October 2013 recommend that people limit
their sedentary leisure time (e.g., computer, smartphone, and televi-
sion) to 2 hours a day and engage in a low level of physical activity.
Children and adolescents are recommended to develop an active life-
style overall, including sports, physical education, walking, and cycling
at home and school. If older adults and people with chronic diseases
are unable to engage in the recommended physical activities, these
groups of people are advised to engage in physical activities to the ex-
tents permitted by their situations.61)
CONCLUSION
Since the beginning of the coronavirus pandemic, social distancing
has become important, and engaging in physical activity in the post-
corona era is difficult. Therefore, a study of the problems of sedentary
lifestyle is considered more valuable at this point.
A sedentary lifestyle has an array of adverse health effects, including
elevated all-cause mortality, CVD mortality, cancer risk, risks for meta-
bolic diseases such as DM, HTN, dyslipidemia, and musculoskeletal
diseases such as knee pain and osteoporosis.
It is indisputable that the negative health impacts intensify with in-
creases in the total daily sedentary times. For this reason, it is impor-
tant to reduce the sedentary time as much as possible.
The findings of studies determining the worst type of sedentary be-
havior varied across studies. Studies observed better health outcomes
with a short sedentary bout with intermittent physical activity, with
light physical activity or simple muscle training, intermittent interrup-
tions of sedentary behavior during work, and rest with physical activity.
Health outcomes also vary depending on the type of sedentary be-
havior and watching television led to the worst outcomes. This may be
attributable to the fact that television watching is a passive sedentary
behavior and that people often consume snacks while watching televi-
sion. Therefore, among the various types of sedentary behaviors, indi-
viduals should refrain from watching television as much as possible,
and snacking should be minimized while watching television.
Even if the total daily sedentary time cannot be reduced for un-
avoidable reasons, it is advisable to engage in sufficient exercise equiv-
alent to or more than 150–300 minutes of MPA per week, as studies
found that physical activity could offset the adverse effects of sedentary
behavior. If sufficient exercise cannot be performed, individuals
should at least perform light physical activity, as opposed to not engag-
ing in physical activity at all as health benefits can be obtained even
with light physical activity, albeit insufficient; they should further try to
increase their physical activity levels as their situations permit.
CONFLICT OF INTEREST
No potential conflict of interest relevant to this article was reported.
ORCID
Jung Ha Park: https ://orcid.org/0000-0002-1269-333X
Ji Hyun Moon: https://orcid.org/0000-0001-6788-7521
Hyeon Ju Kim: https://orcid.org/0000-0002-9103-3275
Mi Hee Kong: https://orcid.org/0000-0003-1464-8812
Yun Hwan Oh: https://orcid.org/0000-0002-1627-7528
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