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Diabetes Prevention
Figure 1: For an Individual Who Sleeps Eight Hours Each
chronic disease risk among adults.
4
The independence of these two
Night, the Remaining 16 Hours of the Day Are Typically
behaviors is further reinforced in studies that have demonstrated
Filled with Domestic and Work Duties
detrimental cardio-metabolic health outcomes for ‘active couch
potatoes’ (i.e. those individuals who meet the physical activity
guidelines but also have high sedentary time; see Figure 3).
7–9
These
findings have led to the emergence of a strong scientific interest in
understanding and influencing sedentary behavior.
In this article, we posit that sedentary behavior (too much sitting) may
Breakfast Work on Transport Watch TV
15 mins computer from work 4 hrs
be at least as important a public health problem as the lack of
3.5 hrs 45 mins
moderate- to vigorous-intensity physical activity (too little exercise). We
put forward an argument for an expanded perspective on physical
activity and health where behavior (both sedentary and physical activity)
Transport Lunch EveningBrisk
to work 30 mins mealwalk
across the day and at all intensities should be considered. We present a
45 mins 30 mins30 mins
brief overview of recent evidence that identifies too much sitting as an
important ingredient of the physical activity and health equation,
Work on
SleepAwake
computer
particularly in relation to cardio-metabolic risk. We emphasise that the
11pm7am
4 hrs
impacts of too much sitting need to be considered as influences that are
Purposeful additional to the still very important clinical and public health concernsSitting
exercise opportunities
about too little exercise.
0.5 hrs 15.5 hrs
Sedentary Behavior—The Downside of
For this hypothetical ‘physically active’ adult who rises from the bed at 7am, a 30-minute brisk
Modern Technology
walk prior to breakfast ensures that the minimum level of ‘purposeful exercise’ is achieved early
If one were able to travel back in time to any period prior to the 1970s
in the day. However, this person then sits for 15 minutes to eat breakfast followed by a car trip
to work that takes 45 minutes. At work, this person spends the next 3.5 hours of the morning
and experience (or re-experience) the lifestyle that existed at that
sitting at the office desk while working on the computer. At lunchtime this person sits in the
time, it would be readily apparent that one would be exposed to a
lunchroom to consume lunch during the 30-minute lunch break. This is followed by another four
hours sitting at the office desk while working on the computer. At the end of the work day, the
remarkably different environment than exists today. In particular, the
person travels in the car for another 45 minutes before sitting down at the dining table to
rapidly evolving innovations that have taken place over the past few
consume the evening meal. The day concludes with watching the favorite television shows with
the family for the next four hours while seated on the sofa. Overall, in percentage terms, for this
decades have led to an ever-increasing reliance on information and
hypothetical person, up to 97% of waking hours may be spent in sitting activities. Yet, by
communication technologies and other labor-saving devices, with
undertaking 30 minutes of brisk walking, according to current public health guidelines, this
person is ‘physically active.’ The new term ‘active couch potato’ is probably more appropriate.
associated decreases in energy expenditure.
10
4
Source: Hamilton et al., 2008.
Effectively, in today’s modern society, prolonged sitting has been
Figure 2: Objectively Measured (Accelerometer) engineered into our lives across many settings, including
Distributions of Sedentary Time, Light-intensity
transportation, the workplace, and the home.
11
This is reflected in
Physical Activity, and Moderate- to Vigorous-
intensity Physical Activity During Waking Hours in
time-use surveys that have shown a progressive rise in the time spent
Australian Adults
in sedentary behaviors such as television (TV) viewing, computer
game use, and ‘surfing the net,’ and also the rapid rise in car
ownership and usage patterns.
12
Moderate to vigorous activities: Sedentary time:
0.7 hrs/day (5%) 9.3 hrs/day (60%)
Sedentary behavior has also been embedded into many workplaces:
computers and labor-saving devices have replaced much of the need
to stand up and move about at work, as well as the physical activity
involved in manual handling tasks. For example, prior to the
introduction of emails it was common practice to walk and talk to a
colleague about work issues, or to send a letter in the post that
invariably required a short walk to a centralised mail room for the
letter to be distributed. Another pertinent example for clinicians and
physicians is the reliance on electronic records of a patient’s medical
Light-intensity activities:
6.5 hrs/day (35%) history, contrasting with previous eras whereby obtaining such
information required a short walk to the medical records office.
27
Source: Heaky et al., 2008.
Unfortunately, the continued interest and pursuit of labor-saving
devices across various settings does not show any signs of slowing
Recent evidence indicates that time spent in sedentary behaviors, down. Therefore, it is possible that we have not yet reached the full
independent of time spent in moderate- to vigorous-intensity activity, potential for prolonged, ubiquitous sitting, nor have we fully
is related to health outcomes and cardio-metabolic biomarkers of uncovered what the health consequences are likely to be.
13
30 US ENDOCRINOLOGY
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