Effects of exercise and BMI on heart disease

The risk of coronary heart disease (CHD) associated with elevated body mass index (BMI) can be considerably reduced by increased physical activity. Coronary heart disease (CHD) or coronary artery disease is the narrowing of the small blood vessels (coronary arteries) that supply blood and oxygen to the heart. Coronary disease usually results from the build up of fatty material and plaque (atherosclerosis). As the coronary arteries narrow, the flow of blood to the heart can slow or stop. This results in chest pain (angina), shortness of breath, heart attack, or other symptoms. CHD can run in the family. It might develop as one gets older or if one is overweight, has high blood pressure, high cholesterol or diabetes. Unhealthy habits, like smoking, eating a diet high in fat and not exercising enough, can also cause CHD. Previous research has shown that physical activity and body mass index (calculated as the ratio of weight to height) independently alter the risk of CHD; however, their combined effect on CHD is not established. To study the combined association of physical activity and body mass index on CHD, researchers in Israel and Boston studied the effects of obesity and inactivity on heart disease using data from the Women's Health Study, which included 38,987 women age 45 years or older who were free of heart disease, stroke, cancer, and diabetes when the study began. At their first examination, 34 per cent of the women were considered physically active, defined as engaging in roughly 30 minutes of moderate-intensity activity five days a week. According to their body mass index, 51 per cent of the women were normal weight, 31 per cent overweight, and 18 per cent were obese. Over an 11-year period, 948 women experienced a heart attack or another form of heart disease. Further analysis showed that body weight and physical activity acted independently from each other to affect the risk of heart disease. And as expected, physically active women with normal body weights had the lowest risk of heart disease. Compared with this group, inactive, obese women were nearly three times more likely to develop heart disease. Individuals in the other activity / weight classes had intermediate risks. The findings reinforce that all women need to participate in increasing amounts of regular physical activity and maintain a healthy weight to reduce, if not eliminate, the risk of heart disease.