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APS Presentation 12:45 p.m. EDT, Monday, April 30
Pressroom presentation Noon EDT, Monday, April 30
Embargoed to the date and time above
Media Contact
Sarah Goodwin
(202) 249-4165 April
28-May 2
Physical Fitness And Habitual Exercise Reduce
Hypertensive Influence Of
Leptin On Blood Pressure, Regardless Of Body Fat
Regular physical activity counts more than percentage
of body fat in terms of systolic blood pressure - a measure of how hard the
body has to work to pump blood against the resistance of the blood vessel
walls, according to a new study reported at Experimental Biology 2007 in
Washington, DC.
The presentation on April 30, by Medical College of
Georgia scientist Dr. Joseph Cannon, is part of the scientific presentation
of the American Physiological Society.
The results, part of an ongoing study of the
relationship between obesity and hypertension at the Medical College of
Georgia, represent another step forward in understanding the role of leptin,
a hormone produced by fat cells. As the amount of fat stored in fat cells
increases, these cells release leptin into the blood to signal to the brain
that the body has had enough to eat. For some reason, the feedback loop does
not work well in obese people. Leptin also influences blood pressure
regulation and may contribute to hypertension in obese individuals.
The results of this new study, says Medical College of
Georgia scientist Dr. Joseph Cannon, suggest that body fat, through leptin,
influences the constantly changing diameter and stiffness of the blood
vessels involved in vessel resistance and hypertension, but that physical
activity and fitness reduce this influence, even in heavy women.
A team of Medical College of Georgia and University of
Georgia physiologists, physical therapists and physician assistants studied
46 healthy women. By design, the group included both sedentary lean women
and active heavy women. The women ranged in age from 25-40 years. Their body
fat, as measured by a sensitive x-ray methodology, ranged from lean (21
percent) to obese (50 percent). Habitual physical activity was determined by
questionnaire, and aerobic fitness was tested using a stationary bicycle.
In the present study, serum leptin concentrations
correlated with blood pressure in women with less than average aerobic
fitness - regardless of their percentage of body fat.The women who were more
aerobically fit showed no relationship between serum leptin and blood
pressure, again regardless of their percentage of body fat.
Since aerobic fitness has some element of genetic
determination, the investigators reanalyzed the data from the standpoint of
habitual physical activity rather than from measures of actual aerobic
fitness. The same relationships were observed: greater physical activity
was associated with lower blood pressure in both heavy and lean women. Serum
leptin levels correlated with blood pressure only in the more sedentary
women.
Co-investigators with Dr. Cannon were Manning J.
Sabatier, Elaina L. Marinik, Sara Haddow, Earl Schwark, Gloria J. Sloan,
Michael F. Bergeron, and Kevin K. McCully. The study was funded by the
Medical College of Georgia Research Institute.
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