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LIFELONG EXERCISE KEEPS HEART YOUNG AND STRONG
Study Suggests Redefining “Normal” Range of Heart Muscle to Consider Lifetime Exercise
New Orleans, LA – Heart muscle size – typically measured by left ventricular (LV) mass – peaks early in life and diminishes with sedentary aging; as it does, it may be associated with cardiac events including diastolic heart failure – a common form of heart failure in the elderly. But new data finds that being physically active over the course of a lifetime can prevent declines in LV mass, helping to preserve the heart‟s youthful elasticity, and also calling into question current definitions for what is considered “normal” and “abnormal” heart mass for healthy people, according to research presented today at the American College of Cardiology‟s 60th Annual Scientific Session. ACC.11 is the premier cardiovascular medical meeting, bringing together cardiologists and cardiovascular specialists to further advances in cardiovascular medicine.
The study – the first to look at the effects of varying levels of lifelong exercise on heart mass – showed that when people are not regularly physically active, the mass of their hearts diminishes with each passing decade of life. On the other hand, elderly subjects who exercised six to seven times a week throughout their adult lives were not only able to preserve this mass but also build on it, showing heart masses greater than healthy young subjects between 25 and 34 years of age.
“One thing that characterizes the aging process by itself is the loss of muscle mass, particularly skeletal muscle,” said Paul Bhella, M.D., John Peter Smith Hospital, Fort Worth, Texas, the presenting author of the study. “But we are showing that this process is not unique to skeletal muscle, it also happens in cardiac muscle. A heart muscle that atrophies is weaker, less capable of responding to increasing demands such as those associated with physical activity, and, in many circumstances, leads to a stiffening of the heart by increasing the relative proportion of connective tissue compared to cardiac muscle.”
Researchers say they are optimistic that their findings will help to: 1) remind cardiologists and radiologists about the benefits of exercise on LV mass and 2) redefine normal ranges so they will take into account how much physical activity people have done throughout their adult life.
Healthy subjects with no evidence of heart disease who were either sedentary or lifelong exercisers were included in the study. Each of the 121 participants was screened extensively based on health and exercise history. The 59 sedentary subjects were recruited from the Dallas Heart Study, a larger multiethnic probability-based sample of Dallas County residents, while the 62 lifelong exercisers were recruited primarily from the Aerobics Center Longitudinal Study, a study which has documented lifelong exercise training patterns in subjects for 25 years.
To quantify exercise, researchers assessed the number of aerobic exercise sessions per week rather than the intensity or duration, which reportedly positively correlated with fitness levels. The lifelong
exercisers, all of whom were over the age of 65, were stratified into one of four exercise groups based on their exercise history: non-exercisers, „casual exercisers‟ (2-3 times a week), „committed exercisers‟ (4-5 times a week) and „Masters athletes‟ (6-7 times a week). After several rounds of screening and testing, heart mass was measured using cardiac MRI.
Sedentary subjects showed heart mass diminished as they aged, while the lifelong exercisers saw heart mass expansion with increasing frequency of exercise. The committed exercisers and Masters athletes had heart mass which was similar to or exceeded that of the healthy young sedentary subjects, a finding that was surprising to authors.
“The data suggest that if we can identify people in middle age, in the 45 to 60 year range, and get them to exercise four to five times a week, this may go a very long way in preventing some of the major heart conditions of old age, including heart failure,” said Benjamin Levine, M.D., the lead investigator of the study. “Defining how to intervene at the right time and with the right dose [of physical activity] are critical questions we need to answer both from a public health standpoint, but also as cardiologists we want our patients to remain healthy and forestall heart problems.”
Nonetheless, Levine and others say it appears that intervening with regular exercise training in middle age, not older age, may afford clinicians the ability to reverse important changes to the heart muscle.
This study was sponsored and funded by the National Institutes of Health.
Dr. Bhella will be available to the media on Saturday, April 2 at 1:00 p.m. CDT in Room 338/339.
Dr. Bhella will present the study “Lifelong Exercise Training Demonstrates a Dose Dependent Effect on MRI Derived Left Ventricular Mass: Implications for Defining Population Norms and Left Ventricular Hypertrophy” on Sunday, April 3, at 10:00 a.m. CDT in Hall F of the Ernest N. Morial Convention Center.
The American College of Cardiology (www.cardiosource.org) represents the majority of board certified cardiovascular care professionals through education, research, promotion, development and application of standards and guidelines – and to influence health care policy. ACC.11 is the largest cardiovascular meeting, bringing together cardiologists and cardiovascular specialists to share the newest discoveries in treatment and prevention, while helping the ACC achieve its mission to address and improve issues in cardiovascular medicine.