A Common Lifestyle-Related Disease
Sitting all day may significantly boost the risk of lifestyle-related
disease even if one adds a regular dose of moderate or vigorous
exercise, scientists said Tuesday.
The health benefits of pulse-quickening physical activity are
beyond dispute -- it helps ward off cardiovascular disease, diabetes
and obesity, among other problems.
But recent scientific findings also suggest that prolonged bouts
of immobility while resting on one's rear end may be independently
linked to these same conditions.
"Sedentary time should be defined as muscular inactivity
rather than the absence of exercise," concluded a team of
"We need to consider that we are dealing with two distinct
behaviours and their effects," they reported in the British
Journal of Sports Medicine.
Led by Elin Ekblom-Bak of the Karolinska Institute in Stockholm,
the scientists proposed a new "paradigm of inactivity physiology,"
and urged fellow researchers to rethink the definition of a sedentary
They point to a recent study of Australian adults showing that
each daily one-hour increase in sitting time while watching television
upped the rate of metabolic syndrome in women by 26 percent --
regardless of the amount of moderate-to-intensive exercise performed.
Thirty minutes of daily physical exercise decreased the risk
by about the same percentage, suggesting that being a couch potato
can cancel out the benefits of hitting treadmill or biking, for
Metabolic syndrome is defined as the presence of three or more
factors including high blood pressure, abdominal obesity, high
cholesterol or insulin resistance.
New research is required to see if there is a causal link between
being sedentary and these conditions and, if so, how it works,
the researchers said.
One candidate is lipoprotein lipase, or LPL, an enzyme that plays
a crucial role in breaking down fat within the body into useable
Recent research has shown that LPL activity was significantly
lower in rats with restrained muscle activity -- as low as one
tenth of the levels of rats allowed to walk about.
The LPL level during such activity "was not significantly
different from that of rats exposed to higher levels of exercise,"
the scientists reported.
"This stresses the importance of local muscle contraction
per se, rather than the intensity of the contraction."
These studies suggest that people should not only exercise frequently,
but avoid sitting in one place for too long, they said.
Climbing stairs rather than using an elevator, taking five-minute
breaks from a desk job, and walking when possible to do errands
rather than driving were all recommended.
January 19, 2010