Physical fitness level predicts death in women more than in men, Chicago researchers have reported in Circulation: Journal of the American Heart Association.
The findings, from the St. James Women Take Heart Project, may change how doctors test and treat women who don't have outward signs of heart disease. Researchers, who began the study in 1992 and followed 5,721 women, said physical fitness was a stronger predictor of death than other measures, including cholesterol, age, blood pressure, diabetes and smoking. A score is totaled and physicians decide if a woman is at a high risk for dying of heart disease and requires treatment.
Earlier studies showed an association between poor exercise capacity and poor survival in men with or without heart disease. This is the first time it's been studied on a large scale in healthy women, said Dr. Martha Gulati, an assistant professor of medicine and preventive medicine at Rush Presbyterian St. Luke's Medical Center in Chicago.
The average age was 52, and none had heart disease, though some had high blood pressure, high cholesterol, diabetes or other risk factors. Each woman had an exercise stress test on a treadmill that became steeper and faster every three minutes until she became breathless, dizzy or exhausted. They measured fitness level in metabolic equivalents (MET). Levels ranged from 1.5 MET in those with low exercise capacity, to 20 MET in the super-active women. Average was 8 MET. Then they compared death from all causes over the next eight years to that initial exercise capacity. For every 1 MET increase in capacity, there was a 17 percent decrease in risk of death, Gulati said. A similar study of men at the Cooper Aerobics Center/Cooper Clinic in Dallas found a 7.9 percent decrease in death in men for every 1 minute increase in exercise time, an amount of exertion nearly equivalent to 1 MET.