The Cooper Institute

Founded in 1970 by the "Father of Aerobics"
Kenneth H. Cooper MD, MPH


Hot Off the Presses From CI: Cardiorespiratory Fitness Strongly Linked to Heart Failure Mortality

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Friday, Aug 16, 2013

Heart failure (HF) is a condition which typically results from a gradual decline in the heart’s ability to pump and fill properly.  It may surprise you to know that HF is the leading cause of hospitalization in the U.S. for individuals ages 65 and older, and accounts for nearly 60,000 deaths annually. There are currently 6 million Americans who are living with heart failure. Well-established risk factors for HF include hypertension, diabetes, age, obesity, smoking, heart valve disease, previous myocardial infarction, and family history of HF.

While sedentary lifestyle has also been identified as a risk factor for HF, previous studies have focused solely on self-reported physical activity levels rather than an actual objective measurement of fitness level. It is important to understand that self-reported level of physical activity from a questionnaire is very different from an objective measurement of physical fitness. The correlation between the two is not nearly as high as most individuals would assume.

In the first study of its kind, my colleagues and I have shown that baseline levels of cardiorespiratory fitness are strongly predictive of future risk of heart failure (HF) mortality.  The study, which was recently published online in Circulation:Heart Failure, followed 44,674 Cooper Clinic men over an average period of 19.8 years. At baseline, all of the men were apparently healthy. Each underwent a comprehensive medical exam that included a maximal treadmill stress test to measure their cardiorespiratory fitness (CRF). Men were placed in categories of low, moderate, and high CRF based on their age and treadmill performance. For example, men who scored in the bottom 20% of their age group were categorized as low fit, while men who scored in the next highest 40% within their age group were categorized as moderate fit. Men who scored in the top 40% within their age group were categorized as high fit. During the 19.8 year follow-up period, 153 men died from HF. Compared with high fit men, moderate and low fit men were 1.63 and 3.97 times more likely to die from HF respectively than high fit men.  Additionally, among men with the same number of risk factors for HF, fit men were substantially less likely to die from HF than unfit men (Figure 1). For example, among men who had 1 risk factor for HF, unfit men were about 4 times more likely to die from HF than fit men.

We concluded that low levels of CRF are a powerful and independent risk factor for HF mortality. All men should be counseled on physical activity by their health care providers, with the goal of achieving at least a moderate level of cardiorespiratory fitness in order to reduce risk of heart failure mortality. In order to achieve a moderate level of fitness, men are encouraged to meet the current public health guidelines for aerobic activity. The guidelines recommend a minimum of 150 minutes per week of moderate intensity aerobic activity. Because exercise has a dose:response relationship, exceeding these guidelines is very likely to result in higher fitness levels, further decreasing the risk of HF mortality.

Here is a summary of what you can do to reduce your risk of developing and/or dying from HF:

  • Monitor and control your blood pressure if you have hypertension.
  • Control your blood glucose level if you have diabetes.
  • Avoid obesity. Lose weight if you are overweight.
  • Avoid tobacco in all forms.
  • Avoid sedentary lifestyle. Strive to attain at least a moderate level of cardiorespiratory fitness compared to others of your same age and gender.