UTSW studies clarify link between exercise, risk of heart disease
High-level exercise doesn’t fuel buildup of coronary artery calcium, but longer duration of exercise might, findings suggest
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DALLAS – June 06, 2024 – Exercising at a high level doesn’t affect the progression of calcium buildup in the arteries, even among older athletes such as marathoners who tend to have higher coronary artery calcium (CAC) scores, according to new research from UT Southwestern Medical Center. But a longer duration of exercise is associated with higher CAC.
The findings of two new studies, published in JAMA Cardiology and the European Journal of Preventive Cardiology, provide more insight into the link between exercise and heart disease, a leading cause of death that kills one person every 33 seconds in the U.S., according to the Centers for Disease Control and Prevention.
“For optimal health over a lifetime, exercise needs to be part of your personal hygiene. These two studies help define how exercise can affect coronary artery calcium,” said senior author Benjamin Levine, M.D., Professor of Internal Medicine in the Division of Cardiology at UT Southwestern who holds the Distinguished Professorship in Exercise Sciences. He is the founding Director of the Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas, where he also holds the S. Finley Ewing Jr. Chair for Wellness and the Harry S. Moss Heart Chair for Cardiovascular Research.
Dr. Levine explained that CAC doesn’t cause heart disease itself; rather, it shows up in medical imaging as a marker of plaque buildup in the heart’s major blood vessels. When this plaque ruptures, it can block blood flow to the heart, causing a heart attack. Thus, if people have lower Agatston units (AU) – a measure of CAC – it is less likely that they have dangerous levels of plaque present in their blood vessels.
Exercise had long been considered protective against plaque buildup. However, surprising research published in 2017 showed that older athletes who engaged in high levels of physical activity, such as marathons or triathlons, were more likely to have high CAC scores. Dr. Levine and his colleagues confirmed these findings two years later in a study involving nearly 21,000 participants, 10 times more than the earlier study. But because participants in both studies took only a single CAC measurement, it was unclear how high levels of exercise affected CAC over time.
In the study published in JAMA Cardiology, Dr. Levine and his colleagues worked with 8,771 men and women, 40 years and older, who had annual checkups over an average of nearly eight years at the Cooper Clinic, a preventive health clinic in Dallas. As part of their checkups, they filled out questionnaires about the length and type of weekly physical activity, which the researchers converted to a measure called metabolic equivalent of task minutes per week (MET-min/wk) that combined exercise duration and intensity. These study participants also received repeat CAC scans.
When Dr. Levine and his colleagues compared the measurements for participants, they found that MET-min/wk levels had no association with CAC progression, even for athletes with very high levels of exercise. The greatest predictor for high CAC levels at the end of the study was elevated CAC at baseline, which can be influenced by a number of factors including diet, cholesterol levels, and other risk factors such as genetics, high blood pressure, smoking, and diabetes, Dr. Levine said.
In the European Journal of Preventive Cardiology study, Dr. Levine and his colleagues investigated whether duration or intensity of exercise might influence CAC levels. This time, the researchers collected data from the medical records of 23,383 male patients between the ages of 40 and 80 at the Cooper Clinic who each had a CAC scan between 1998 and 2019. As in the previous study, a questionnaire recorded the intensity and duration of their exercise routines.
When the researchers compared the participants’ CAC scores and exercise habits, they found that higher average intensity of physical activity was associated with less CAC at any age and at any weekly duration of activity. However, the opposite was true for duration of activity – exercising relatively longer was associated with more CAC at any age and at any average intensity of activity.
Together, Dr. Levine said, these results add new insight into the multifaceted relationship between exercise behaviors and CAC. However, he noted that even exercise behaviors associated with higher CAC are still beneficial – his own research and that of other investigators has shown that staying fit reduces the risk of death from any cause as well as the risk of chronic diseases including Type 2 diabetes, some types of cancer, and depression as well as cardiovascular disease.
Other UTSW researchers who contributed to the study in JAMA Cardiology are Amit Khera, M.D., M.S., Director of the Preventive Cardiology Program, Professor of Internal Medicine, and Associate Chief of Cardiology for Faculty Development; and medical student William M. Turlington.
Dr. Khera holds the Dallas Heart Ball Chair in Hypertension and Heart Disease.
About UT Southwestern Medical Center
UT Southwestern, one of the nation’s premier academic medical centers, integrates pioneering biomedical research with exceptional clinical care and education. The institution’s faculty members have received six Nobel Prizes and include 25 members of the National Academy of Sciences, 21 members of the National Academy of Medicine, and 13 Howard Hughes Medical Institute Investigators. The full-time faculty of more than 3,100 is responsible for groundbreaking medical advances and is committed to translating science-driven research quickly to new clinical treatments. UT Southwestern physicians provide care in more than 80 specialties to more than 120,000 hospitalized patients, more than 360,000 emergency room cases, and oversee nearly 5 million outpatient visits a year.