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Riyahd, Saudi Arabia
Dr. Hassan is Consultant and Deputy Head, Adult Cardiology, Department of Cardiovascular Diseases, King Faisal Specialist Hospital and Research Center. Dr. Fawzy is a consultant adult cardiologist.
Correspondence to: Walid Hassan, MD, FCCP, Consultant and Deputy Head, Adult Cardiology, Department of Cardiovascular Disease (MBC#16) King Faisal Specialist Hospital and Research Center, PO Box 3354, Riyadh 11211, Saudi Arabia; e-mail: hassanw{at}kfshrc.edu.sa
Historically, the beneficial effects of exercise on the coronary heart disease risk profile are less marked in women compared with men.1 In previous observational studies,2 a lower fitness level was associated with a fourfold to sevenfold increased risk for all-cause mortality in women, and higher activity levels have been associated with decreased relative risks for coronary artery disease (CAD) [0.44] and stroke [0.51], compared with a lower activity level independent of other risk factors.
Physical inactivity presents in > 65% of the elderly. In the 10-year follow-up of the Multiple Risk Factors Intervention Trial,3 subjects in both treatment groups who engaged in moderate physical activity had a 27% lower CAD mortality rate than less active subjects.3 Mechanisms by which increased exercise benefits patients with CAD may include improvement in the following: endothelial function, vasodilatory reserve, vascular conditioning, capillary density, oxidative enzyme content, mitochondrial number and size, high-density lipoprotein, collateral circulation (possible), insulin resistance, BP, body weight, psychological benefits, and increased self confidence. In one angiographic study,4 there were favorable changes in the morphology of obstructive lesions.
The conditioning effect of exercise on skeletal muscles allows a greater workload at any level of total body oxygen consumption. By decreasing the heart rate at any level of exertion, a higher cardiac output can be achieved at any level of myocardial oxygen consumption. The combination of these two effects of exercise conditioning permits the patient with chronic stable angina to increase physical performance substantially following institution of a continuing exercise program.5
One randomized trial6 of cardiac rehabilitation with exercise training demonstrated a statistically significant cardiovascular mortality benefit. Two meta-analyses78 showed that overall mortality and cardiovascular mortality, defined as fatal reinfarction and sudden death, were reduced by 20 to 25% in patients randomized to exercise training. We know that the most accurate measure of exercise capacity is the maximal oxygen uptake, and recently demonstrated that improvement in peak aerobic power (
O2peak) was associated with prognostic implications and reduction in cardiac mortality in older women with CAD.9
The article by Hung and colleagues in this issue of CHEST (see page 1026) provides some important insights on two methods of exercise intervention in a group of older women with CAD that can improve O2peak, muscle strength, and quality of life (QOL). They compared the effect that aerobic training (AT) [treadmill and cycle exercise] and combined aerobic and upper- and lower-extremity strength training (COMT) had on several variables in 18 older women (60 to 80 years old) with documented CAD (after exclusion of high-risk patients). Exercise duration was 30 min per session, 3 d/wk, for 8 weeks. Irrespective of the type of training, there was statistically significant posttraining improvement in O2peak, distance walked in 6 min, lower-extremity strength, and emotional, physical, social, and global QOL. COMT resulted in a significant improvement in upper-extremity strength (no change after AT), and a greater absolute improvement in emotional, physical, social, and global QOL. Despite the small number of subjects in the study group, no mention of left ventricular systolic and diastolic function, and the presence and quantity of myocardial ischemia, Hung and colleagues must be congratulated for this prospective investigation, which provides important information for us to use in cardiac rehabilitation programs, and to be applied in future large-scale trials with longer follow-up to determine long-term morbidity and mortality benefits.
References
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