A high level of fitness may extend the lives of women with metabolic syndrome, according to new findings presented today by a cardiologist at Northwestern Memorial Hospital at the annual American Heart Association Scientific Sessions.
Researchers followed nearly 6,000 women who had no signs of heart disease when the study launched in 1992. Over the next nine years, those with metabolic syndrome were 57 percent more likely to die than those who didn't have the cluster of risk factors that defines metabolic syndrome. But when researchers controlled the study for women with metabolic syndrome who had higher levels of cardiorespiratory fitness, this elevated risk nearly disappeared - both overall deaths and deaths specific to heart disease fell to rates similar to those of the group of women without metabolic syndrome.
"Through some mechanism, cardiorespiratory fitness may be protective against the adverse effects of metabolic syndrome," says lead researcher Martha Gulati, MD, co-director of the Center for Women's Health at the Bluhm Cardiovascular Institute of Northwestern Memorial Hospital. "Fitness has a protective effect, likely because it reduces other risk factors, lowers heart rate and conditions the heart to respond to stress."
Cardiorespiratory fitness can be determined by measuring the maximal oxygen uptake for a given workload and can be expressed in metabolic equivalents (METs). One MET is defined as the energy it takes to sit quietly. This study defined higher levels of cardiorespiratory fitness as women who are able to perform activities at greater than 8 METs (approximate to being able to run a mile in 12 minutes or faster).
Metabolic syndrome, which increases the risk of cardiovascular disease and diabetes, is defined as having three or more of the following risk factors: a waist circumference of greater than 35 inches in women; high blood pressure; elevated triglycerides; low levels of high-density lipoprotein (HDL); or high fasting glucose levels.
In August of this year, a related study by Dr. Gulati was published in the New England Journal of Medicine which found that otherwise healthy women whose exercise capacity was less than 85 percent the age-predicted value had twice the risk of death compared to women reaching at least 85 percent. "Our findings should provide an added incentive for women, with and without metabolic syndrome, to start working out," Gulati said. "In many aspects, women can take control over their own health and longevity and exercise is one of the keys."