“Obesity Sleuths” Find Chronic Diseases are Linked to A
Breakdown Response to What Our Human DNA Is Expecting
The need for physical activity is hotwired into the
body’s expectations; When that activity does not occur, nutritional “thrifty
genes” react, causing a steep rise in common chronic conditions
BETHESDA, MD – (July 10, 2002) – The results of the most
extensive research investigation into the relationship between chronic
health conditions and physical inactivity have been released by a team of
“obesity sleuths.” They conclude that today’s skyrocketing levels of
chronic diseases are due to the collision between the body’s
total gene complement of a set of chromosomes,
-- programmed 10,000 years ago to anticipate physical exertion, and
the inactivity endemic to 21st century sedentary societies. Nutritional
“thrifty genes” may further exacerbate the deterioration of the human body,
which takes the form of common, chronic disorders, once thought to be rare.
The Study
The study entitled “Waging War on Physical Inactivity: Using Modern
Molecular Ammunition Against an Ancient Enemy,” is the latest report from
the obesity research team of Frank W. Booth and Espen E. Spangenburg, both
of the Departments of Biomedical Sciences and Physiology and the Dalton
Cardiovascular Institute at the University of Missouri, Columbia, MO; Manu
V. Chakravarthy, of the Department of Internal Medicine, University of
Pennsylvania, Philadelphia, PA; and Scott E. Gordon, of the Departments of
Exercise and Sports Sciences and of Physiology and the Human Performance
Laboratory, East Carolina University, Greenville, NC. Their study appears in
the current edition of the Journal of Applied Physiology, a
publication of the American Physiological Society.
The team set out to identify the underlying genetic and
cellular/biochemical bases of why a sedentary lifestyle produces chronic
health disorders. They support the hypothesis that humans have inherited a
genome programmed for physical activity by selective forces from the Late
Paleolithic era (10,000 years ago), when
physical activity was necessary for survival. Another associated hypothesis
that was examined in this research effort is that a lack of physical
activity leads to failure of the maintenance of normal signaling by cellular
networks that activate that genome. Since the normal orchestration of
protein expression in cells in humans was selected during evolution, when
physical activity was higher than today, an altered protein expression of
cells from sedentary individuals is associated with a higher incidence of
chronic conditions.
As part of their efforts, new conclusions have been reached on how
physical inactivity affects at least 20 of the most chronic and deadly
medical disorders. They suggest that all these conditions share common
genetic inheritances that were supported by physical activity. When
physical activity diminished, chronic health conditions occurred.
Needs for the Paleolithic Age
Daily physical activity was an integral, obligatory aspect of our
ancestor’s existence. The weekly activity pattern of hunter-gatherers of the
Paleolithic Stone Age period (c. 8,000 B.C.) required several days of
fairly intensive physical activity followed by days of rest and light
activity. Men commonly hunted from one to four consecutive days each week
while women gathered every two to three days. The physical labors involved
in tool making, butchering, food preparation, carrying firewood and water,
and moving to new campsites were supplemented by dances, often lasting
hours, as a major recreational activity in many cultures.
(Lack of) Needs for 21st Century
Americans
Twenty-first century Americans still possess late
Paleolithic, pre-agricultural hunter-gatherer genes, and, perhaps
nutritional “thrifty genes.” Since our food abundant society makes physical
activity no longer obligatory for survival, the sedentary lifestyle has
emerged, disrupting the normal homeostatic mechanisms that have been
programmed for the proper metabolic fluctuations necessary to maintain
health. Physical inactivity interferes with the genome thus becoming an
initiating factor in the molecular mechanisms of disease.
This assessment of chronic disorders addressed a wide
range of maladies that affect a considerable number of Americans. Disorders
were considered and conclusions were reached.
Highlights include:
Cancer
-
Breast cancer: Sedentary females, compared with
physically active women, are less likely to have primary and secondary
anenorrhea, delayed menarche, and irregular cycles, all associated with a
reduced development of breast cancer.
-
Colon cancer: Physical inactivity was the risk
factor most consistently shown to be associated with the increased risk of
colon cancer. A 50 percent reduction in the incidence of this disease was
found in those with the highest level of physical activity.
-
Pancreatic cancer: Walking or hiking less than 20
minutes a week was associated with twice the risk of pancreatic cancer
when compared with those who performed the exercise for more than four
hours a week.
-
Melanoma: Sedentary men and women had a 56 and 72
percent, respectively, higher incidence of melanoma than those exercising
five to seven days a week.
Cardiovascular Diseases
-
Heart disease, coronary artery disease, angina, and
myocardial infarction: Undertaking a moderate-intensity physical
activity would prevent 250,000 deaths each
year, 12 percent attributed to these medical conditions.
-
Heart disease: congestive heart failure: Exercise
may improve the condition of people afflicted with this disorder; physical
inactivity may be a determinate factor to their time of death.
-
Hypertension: Tests found that inactivity led to
blood pressures in sedentary individuals being substantially higher than
in those who were active.
-
Stroke: Physical activity lowers blood pressure,
facilitates weight loss, and decreases the chance for Type 2 diabetes, a
major cause of strokes.
Metabolic Diseases
-
Type 2 diabetes: Most of the prevalence of Type 2
diabetes in the United States can be attributed to a change in lifestyle
that involves a genome evolved from a Paleolithic lifestyle. Cultures
that still have hunter-gatherers have low incidence of this disease.
-
Obesity: Sedentary individuals can lower their risk
of many disorders by increasing their physical activity, regardless of
whether they are normal or overweight.
Musculoskeletal Disorders
-
Osteoarthritis: Appropriate exercise, both
therapeutic and recreational, is an effective therapy in the successful
management of this disorder. The benefits are flexibility, muscular
conditioning, and cardiovascular and general health.
-
Rheumatoid Arthritis: Exercise for patients with
this disorder minimizes loss in muscle strength but not in bone loss.
Conclusions
This effort clearly points out that a sedentary
lifestyle leads to a breakdown in the body’s biomedical system and a failure
of genes leading to chronic disease. Now,
the American public has a baseline of information of how to develop an
optimum design for living that will contribute to a healthy lifestyle and to
the avoidance of disorders caused by inactivity.
This research also suggests that the publicized
searches for genes causing chronic illnesses are too limited. In addition,
scientists should explore how selected “activity” genes are misexpressed as
a result of a sedentary lifestyle. These findings challenge those engaged
in using the human genome sequence to fight disease to recognize the
“activity genes” that produce diseases when
inactivity occurs. They repeat their call for Americans to participate in
more physical activity to prevent the advent of a wide range of chronic
disorders.
Source: Journal of Applied Physiology,
July 2002.
-end-
The American Physiological
Society (APS) was founded in 1887 to foster basic and applied science, much
of it relating to human health. The Bethesda, MD-based Society has more than
10,000 members and publishes 3,800 articles in its 14 peer-reviewed journals
every year.
***
Editor’s Note: To set up
an interview with a member of the research team, please contact Donna Krupa
at 703.527.7357 (direct dial), 703.967.2751 (cell) or
djkrupa1@aol.com.
