According to a recent LIFE Study, an aerobically based, moderately intensive physical activity program was not associated with reduced cardiovascular events in spite of the intervention’s previously documented ability to prevent mobility disability.
The increasing urbanization and mechanization of the world has reduced our levels of physical activity. If you are physically active you will increase your life span, and at any age, are protected against a multitude of chronic health problems including many forms of cardiovascular disease (CVD). Many observational studies demonstrate that greater physical activity (PA) is associated with lower rates of incident and recurrent myocardial infarction (MI), slowing the progression of coronary artery disease and can prolong event-free survival in patients undergoing stent placement.
The Lifestyle Independence and Interventions for Elders (LIFE) Study, reported in JAMA Cardiology, compared PA with successful aging (SA) and studied the effect of a structured program in preventing mobility disability in older adults with functional limitations and also its effect on CVD, if any.
The LIFE study was a multicenter, single-blinded, randomized trial of PA compared with health education (SA) conducted at 8 field centers across the United States between February 2010 and December 2013. A total of 1635 sedentary men and women aged 70 to 89 years, at high risk for mobility disability (based on objective lower extremity functional limitations as measured by the Short Physical Performance Battery (SPPB) score of 9 or lower of a total of 12) were randomized. The eligible participants were able to walk 400 m in 15 minutes or less, had no major cognitive impairment and could safely participate in the intervention.
Participants were randomized to a PA or to a SA program via a secure, internet-based data management system. Both groups received an initial individual 45-minute face-to-face introductory session by a health educator. The PA intervention was conducted over an average of 2.5 years and included moderate aerobic activity, mostly walking, for at least 150 minutes per week, strength training, flexibility training, and balance training.The SA intervention consisted of weekly health education sessions for 6 months, then monthly.
CVD events were a predefined tertiary outcome and consisted of a composite of MI, hospitalized angina, congestive heart failure, ruptured abdominal aortic aneurysm, hospitalization for carotid and peripheral artery disease or outpatient revascularization for any stroke, transient ischemic attack and even death. The baseline assessments included self-reported demographic and contact information, medical and hospitalization history, medication inventory, ECG, physical examination, health care use, physical activity assessed with cognitive testing, 400 m walk test, the SPPB, body weight, blood pressure, and pulse rate. These measures were repeated during follow-up at varied intervals and were assigned a categorical score ranging from 0 (inability to complete the test) to 4 (best performance). A summary score ranging from 0 (worst performers) to 12 (best performers) was calculated by summing the 3 component scores. Baseline characteristics were summarized by intervention group using mean (SD) or percentages.
Out of the 1635 LIFE study participants, 67% were predominantly women, with a mean (SD) age of 78.7 (+/-5.2) years; 20% were African-American, 6% were Hispanic or another race or ethnic group, and 74% were non-Latino white. The overall prevalence of CVD at baseline was 129 (8%) for MI, 104 (6.5%) for stroke, and 71 (4.2%) for heart failure; hypertension and diabetes were common (1151 [69%] and 415 [26%], respectively), while only 50 (3%) currently smoked cigarettes; mean (SD) body mass index was 30 (+/-5.5), blood pressure, lipid and cholesterol levels varied. Reflecting a high risk of disability, the mean SBBP was 7.4.
New CVD events occurred in 121 of 818 PA participants (14.8%) and 113 of 817 SA participants (13.8%). For the more focused combined outcome of MI, stroke, or cardiovascular death, rates were 4.6% in PA and 4.5% in the SA group. Among frailer participants with an SPPB score of less than 8, total CVD rates were 14.2% in PA vs 17.7% in SA, compared with 15.3% vs 10.5% among those with an SPPB score of 8 or 9. With the limited end point, the interaction was not significant, with an Hazard Ratio of 0.94 for an SPPB score less than 8 and 1.20 for an SBBP score of 8 or 9.
There were no differences in baseline characteristics by SPPB subgroup such as prevalent CVD, CVD risk factors, physical activity, or perceived level of exertion at baseline. There were more silent MIs by ECG in the higher SPPB subgroup but not more cardiovascular procedures, and this did not explain the relatively higher risk in the higher SPPB subgroup. Over the course of the study, higher SPPB subgroups had higher measured activity and lower perceived exertion than the lower SBBP subgroups in both the PA group and the SA group. However, there were several important limitations to this study (i.e., the follow-up was only 2.5 years on average and the statistical power was limited to detect small differences in rates or in subgroups).
In the present LIFE study, a pattern of relatively more favorable benefit for older and more poorly functioning individuals was observed for the primary and other secondary outcomes, thus proving to be safe and efficacious for the prevention of major mobility disability and perhaps improved cognition. Despite of the lack of association between increased PA and reduced CVD, efforts to promote a program of sustained walking and weight training in frail older adults should be sustained.
Written By: Dr. Pratibha Bharti, PhD Biotechnology