MedicalResearch.com Interview with:
Deepika Laddu PhD
Department of Physical Therapy
College of Applied Health Sciences
The University of Illinois at Chicago
Chicago, IL 60612
MedicalResearch.com: What is the background for this study?
Response: Recent findings in population-based cohort studies on cumulative exercise dose have caused some controversy and debate showing U-shaped trends of association between physical activity and disease risk. Our objective was to better understand this association between physical activity and cardiovascular disease risk from young adulthood to middle age.
Given that engagement in physical activity is a continuously evolving behavior throughout life, this study looked at the physical activity trajectories of 3,175 black and white participants in the multicenter, community-based, longitudinal cohort CARDIA study who reported physical activity patterns over 25 years (from 1985 through 2011), and assessed the presence of coronary artery calcification, or CAC, among participants. Unique to this study is the evaluation of long-term exercise patterns from young adulthood into middle age in CARDIA participants. Based on the trajectories (or patterns of change) of physical activity over 25 years, participants were categorized into three distinct trajectory groups: trajectory group one was defined as exercising below the national guidelines (less than 150 minutes a week), group two as meeting the national guidelines for exercise (150 minutes a week), and group three as exercising three-times the national guidelines (more than 450 minutes a week).
MedicalResearch.com: What are the main findings?
Response: Participants in trajectory group three, or those who exercised the most, were 27 percent more likely to develop coronary artery calcification by middle age (defined as ages 43 to 55), than participants in trajectory group one. When these findings were stratified by race and gender, we found that white men were at the highest risk– 86 percent more likely to have CAC by middle age than participants in trajectory group one. However, no higher odds of coronary artery calcification was observed for black participants who exercised at this level. Other ethnicities were not included in this study.
MedicalResearch.com: What should readers take away from your report?
Response: At the end of the day, exercise is medicine, and one of the most proven and effective methods of disease prevention. While our study suggests that white men who exercise more than three times recommended guidelines may have a higher burden of f coronary artery calcification, it does not suggest that anyone should stop exercising. However, these findings may lend a possible explanation of the mechanisms of previous studies that have shown increased vascular risk associated with very high levels of physical activity.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: There is a lot that still remains unanswered from this study. For example, high levels of exercise over time may cause stress on the arteries leading to higher coronary artery calcification, however this plaque buildup may well be of the more stable kind, and thus less likely to rupture that causes heart attack. At this time, our study did not evaluate for outcomes such as heart attacks and death, which is something our future work will focus on. Because the study results show a significantly different level of risk of accumulating CAC between black and white participants, the data also provides rationale for further investigation, especially by race, into the other biological mechanisms for coronary artery calcification risk in people with very high levels of physical activity. Additionally, we really need to have a better understanding into the mechanisms of how physical activity provides cardiovascular benefit, at what dose and prognosis of physical activity is needed to accumulate cardiovascular benefit, and whether the possible existence of an upper limit for cardiovascular benefit associated with higher PA levels is observed in other populations.
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Deepika R. Laddu, Jamal S. Rana, Rosenda Murillo, Michael E. Sorel, Charles P. Quesenberry, Norrina B. Allen, Kelley P. Gabriel, Mercedes R. Carnethon, Kiang Liu, Jared P. Reis, Donald Lloyd-Jones, J. Jeffrey Carr, Stephen Sidney. 25-Year Physical Activity Trajectories and Development of Subclinical Coronary Artery Disease as Measured by Coronary Artery Calcium. Mayo Clinic Proceedings, 2017; DOI: 10.1016/j.mayocp.2017.07.016
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