Researchers at Johns Hopkins University School of Medicine in Baltimore found that exercise improved overall fitness, but the 23 percent fewer cases were more strongly linked to reductions in total and abdominal body fat and increases in muscle leanness, rather than improved fitness.
The researchers' findings raise the importance of physical exercise in treating both men and women with the metabolic syndrome, a clustering of three or more risk factors that make it more likely for a person to develop heart disease, diabetes and stroke - including high blood pressure, elevated blood glucose levels, excess abdominal fat and abnormal cholesterol levels.
The study, published in the American Journal of Preventive Medicine on December 30th, is believed to be the first to focus on the role of exercise training in treating metabolic syndrome in older persons, a group at high risk for heart disease and diabetes.
To assess the benefits of a fixed programme of exercise training, the Johns Hopkins team studied a group of 104 older people for a six-month period between July 1999 and November 2003. All of the participants had no previous signs of cardiovascular disease beyond untreated, mild hypertension. One half of the study participants were randomly assigned to a control group that received a booklet that encouraged increased activity, such as walking, to promote good health. The other half participated in a supervised series of exercises for 60 minutes, three times per week. These exercises included cycling.
The Johns Hopkins team measured the changes in participants' risk factors, body fat, and muscle and fitness levels, and found substantial improvements in the group that was exercising for six months. Aerobic fitness, as measured by peak oxygen uptake on a treadmill, increased by 16 percent, and strength fitness increased by 17 percent. The average weight loss in this group was only four pounds because much of the loss of fat was offset by increased muscle mass. The fat in the abdominal region, by itself an important risk factor for heart and metabolic syndrome, was reduced by 20 percent among people in the exercising group. The group that was not exercising had either no or significantly less improvement than the exercising group.
At the beginning of the study, 43 percent of all participants had the metabolic syndrome. By the end of the study, participants in the exercising group had no new cases of metabolic syndrome, and the condition had resolved in nine of them, a reduction of 41 percent. In the control group, eight participants no longer had the syndrome, while four new cases appeared, resulting in an overall reduction of only 18 percent.
"A novel finding of our study was that the changes in disease risk factors with exercise training were more closely related to reductions in body fat, particularly abdominal fat, and increases in muscle tissue, rather than improvements in fitness," said lead study investigator and exercise physiologist Kerry Stewart, Ed.D., professor of medicine and director of clinical exercise physiology and heart health programs at The Johns Hopkins University School of Medicine and its Heart Institute.
"The results also confirm the value of exercise for managing multiple risk factors. Because so many older persons have or are at risk for metabolic syndrome, this study provides a very strong reason for individuals to increase their physical activity levels. They will reduce their fatness, and increase their fitness and leanness, while reducing their risk for heart disease and diabetes."