Walking for at least 40 minutes several times per week at an average to fast pace is associated with a near 25 percent drop in the risk of heart failure among post-menopausal women, according to new research being presented at the American College of Cardiology's 67th Annual Scientific Session. The benefit appears to be consistent regardless of a woman's body weight or whether she engages in other forms of exercise besides walking.
About 6.5 million adults have heart failure, a condition in which the heart becomes too weak to pump enough blood to meet the body's needs. The risk of heart failure rises with age; women 75-84 years of age are three times as likely to have heart failure compared with women 65-74 years old.
"We already know that physical activity lowers the risk of heart failure, but there may be a misconception that simply walking isn't enough," said Somwail Rasla, MD, a cardiology fellow at Saint Vincent Hospital, who conducted the study during his residency at Brown University. "Our analysis shows walking is not only an accessible form of exercise but almost equal to all different types of exercise that have been studied before in terms of lowering heart failure risk. Essentially, we can reach a comparable energetic expenditure through walking that we gain from other types of physical activity."
Because walking can be done any time and doesn't require special equipment, the results put meaningful physical activity within reach for older women who may be hesitant to join a gym or begin a new workout routine.
The study, which analyzed walking behavior and health outcomes among 89,000 women over a more than 10-year period, is the first to examine, in detail, the benefits of walking by parsing the effects of walking frequency, duration and speed. It is also the first to specifically focus on the risk of heart failure among women over age 50.
The research is based on an analysis of data from the Women's Health Initiative, a large study funded by the National Heart, Lung, and Blood Institute that collected data about women's habits and health outcomes from 1991-2005. Participants were between 50 and 79 years of age at enrollment. Rasla and colleagues extracted data for women who, at baseline, were able to walk at least one block and did not have heart failure, coronary artery disease or cancer.
Based on information from participant questionnaires, the women's walking behavior was categorized according to frequency, duration and speed. Researchers also assessed the women's overall energy expenditure from walking by combining all three of these variables into a calculation known as Metabolic Equivalent of Task (MET). Those in the highest tertile for MET per week were 25 percent less likely to develop heart failure compared with those in the lowest tertile.
The findings suggest walking frequency, duration and speed each contribute about equally to this overall benefit. Women who walked at least twice a week had a 20 to 25 percent lower risk of heart failure than those who walked less frequently. Those who walked for 40 minutes or more at a time had a 21 to 25 percent lower risk than those taking shorter walks. Women walking at an average or fast pace showed a 26 and 38 percent lower risk of heart failure, respectively, compared with women who walked at a casual pace.
Researchers said the results were consistent across different age categories, ethnicities and baseline body weight in post-menopausal women, suggesting the findings can be generalized to apply to most women above 50 years old.
"We actually looked at women with four different categories of body mass index (BMI) and found the same inverse relationship between walking behavior and the risk of heart failure," Rasla said. "The results show that even obese and overweight women can still benefit from walking to decrease their risk of heart failure."
The analysis accounted for a variety of heart disease risk factors, such as smoking, alcohol use, family and medical history, use of hormones and overall amount of physical activity. Walking behavior was assessed based on self-reporting by participants during the study. Researchers were unable to account for the potential effects of exercise or walking habits earlier in life.
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