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News Briefs

Physical Activity and Cardiovascular Disease in Humans

Joyner, Michael J.

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Exercise and Sport Sciences Reviews: January 2001 - Volume 29 - Issue 1 - p 1-2
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OVERVIEW

Physical activity of many types can protect individuals from a host of cardiovascular and metabolic diseases and benefit individuals who already have overt disease. Exercise is also emerging as perhaps the key intervention that limits or reverses age-related declines in physiologic function. With these generally well-known principles as a background, three key articles that cover important points related to physical activity and cardiovascular disease are reviewed in this issue’s News Brief. These articles address the following questions:

  1. Do older individuals need to be screened with an exercise test before starting an exercise program?
  2. What kind of persons have exertion-related acute myocardial infarctions (MIs)?
  3. Can older patients with congestive heart failure benefit from endurance exercise training?

Gill, T.M., L. DiPietro, and H.M. Krumholz. Role of exercise stress testing and safety monitoring for older persons starting an exercise program.JAMA284:342–349, 2000. Gill, DiPietro, and Krumholz discuss the risk of initiating an exercise program in older persons and the need for routine exercise testing before initiation of an exercise program. They review a large number of studies that provide evidence that a variety of forms of physical activity either reduce adverse outcomes or increase favorable outcomes in individuals older than 75 years of age. They then discuss what is known about the relative risk of MI in older individuals during and after physical activity. Next, they discuss a variety of evidence in the context of ACSM and American Heart Association guidelines about the need for screening in middle-aged individuals with and without risk factors for cardiovascular disease before starting an exercise program. The authors then attempt to take a global look at the “key differences between older and younger persons”; they hypothesize and discuss several important issues.

First, older individuals with no reported history of coronary artery disease or hypertension are likely to have a wide variety of ECG abnormalities both at rest and during exercise that might diminish the prognostic/diagnostic accuracy of stress testing. Second, the authors argue that because it is likely that there is a “large reservoir” of asymptomatic heart disease in older persons, routine exercise testing and the associated potential for unclear diagnostic outcomes might lead to a large increase in invasive work-ups for cardiovascular disease. They point out that because there is strong evidence to support aggressive evaluation and intervention in otherwise asymptomatic individuals, this will be a huge change in medical practice that would divert resources from the healthcare system and place a variety of older persons at risk for atherogenic complications and other problems associated with the application of “high-tech” treatment for their otherwise asymptomatic coronary disease. Third, many individuals in this age group have orthopedic or other chronic medical conditions that limit their ability to exercise sufficiently hard to obtain a stress test that has high predictive value.

The authors then lay out a variety of unanswered questions related to exercise testing and training in older persons. These are followed by recommendations to minimize the risk of adverse cardiovascular events. Most importantly, they stress the need for comprehensive teams to help older persons begin exercise training, including the need for exercise physiologists. They also stress the role of a comprehensive history and physical examination. A variety of contraindications or indications that would require additional evaluation are also listed. When all this information is taken in total, the authors conclude that “current guidelines regarding exercise testing are not applicable for the vast majority of older persons who are interested in restoring or enhancing their physical function through a program of physical activity and exercise.”

Discussions about how best to preserve and enhance the health of the aging population continue, and this special communication is an excellent example of how our policies on these topics should evolve.

Giri, S., P.D. Thompson, F.J. Kiernan, J. Clive, D.B. Fram, J.F. Mitchel, J.A. Hirst, R.G. McKay, and D.D. Waters. Clinical and angiographic characteristics of exertion-related acute myocardial infarction.JAMA282:1731–1736, 1999. Giri and colleagues address questions related to the characteristics of individuals who experience exertion-related MIs. The authors seek to understand more about the apparent well-known paradox that habitual physical activity appears to reduce the risk of MI and other cardiac events on a long-term basis but that when these events do occur, they are more likely to occur during or just after periods of physical activity. The authors studied 1048 consecutive patients who were hospitalized for acute MI. As a result of a variety of factors over which the authors had little control, 640 of these patients were evaluated with angiography and treated with primary angioplasty. Of these 640 patients, 64 had an exertion-related MI. Some interesting characteristics were observed in the patients with exertion-related MIs. First, they were more likely to be male, hyperlipidemic, and smokers. They were also more likely to present with ventricular fibrillation and heart failure. They were typically in the very low or low physical activity group. Based on these observations, the authors conclude that the relative risk of MI during exertion is 10.1 times greater than the risk at other times of the day for their patients as a whole, and that among the highest risk patients, who were minimally active, the relative risk is 30 times greater. The authors then conclude that individuals likely to experience exertion-related MIs are habitually inactive and have multiple risk factors for cardiovascular disease. They point out that these individuals may benefit from modest exercise training in conjunction with aggressive risk factor modification before they begin a period of more vigorous physical activity or exercise training.

How the exercise community gets individuals at high risk for heart disease to take more responsibility for their health continues to be a major challenge. Prevention would surely be a better option for these patients.

Hambrecht, R., S. Gielen, A. Linke, E. Fiehn, J. Yu, C. Walther, N. Schoene, and G. Schuler. Effects of exercise training on left ventricular function and peripheral resistance in patients with chronic heart failure: a randomized trial.JAMA283:3095–3101, 2000. Hambrecht and colleagues evaluated the effects of exercise training on left ventricular function in patients with heart failure. In this study, 73 men (70 years old or younger) with heart failure and ejection fractions of approximately 27% were studied after 2 weeks of inpatient exercise that consisted of multiple 10-min bouts. Subsequently, half were randomized to exercise at home (20 min·d−1 at 70% peak o2) and half were randomized to no intervention. Six months of training led to a variety of statistically significant improvements in the exercise group compared with the control group. The severity of heart failure was diminished; improved maximal ventilation, exercise time, and exercise capacity were seen in the exercise group. Resting heart rate and stroke volume were also improved. Ejection fraction improved, and cardiomegaly was reduced.

This article showed that there can be modest central adaptations to exercise training in patients with heart failure. These central adaptations are likely to complement the well-known peripheral adaptations to exercise training in people with reduced ejection fractions. Two additional factors are worth noting. First, the functional status of the exercise-trained patients improved dramatically. Second, this is an especially important observation because with a variety of new drug therapies, heart failure is becoming a more “chronic” condition and patients with low ejection fractions are now surviving for many years. In this context, it appears that physical activity will play a key role in helping patients with heart failure live longer and keeping them up and about and functioning at a high level.

SUMMARY

The articles reviewed in this News Brief of Exercise and Sport Sciences Reviews address fundamental issues related to physical activity and cardiovascular disease in humans. Based on these reports, it appears that the need for extensive screening of older patients before beginning modest or mild physical activity programs may not be needed. Certainly, further discussion of this issue is warranted. By contrast, in individuals who are very inactive with multiple risk factors, the risk of a cardiac event during unsupervised exercise appears to be remarkably increased. Finally, modest exercise rehabilitation might have dramatic effects in improving the functional status of patients with heart failure.

© 2001 Lippincott Williams & Wilkins, Inc.