Updated meta-analysis of prevention of cardiovascular mortality by regular physical activity

Physical activity as an intervention at the individual level is now recognized as a valid countermeasure to reduce premature cardiovascular and all-cause mortality. Conversely, a sedentary lifestyle – together with smoking, obesity and malnutrition – are the four pillars of high risk for many non-communicable diseases. Starting with the landmark studies of Paffenbarger et al.1 and Blair et al.,2 more than 100 epidemiological studies have examined the association between regular physical activity and a reduction in risk to health with mortality as a hard endpoint. There is a continuum from inactivity to regular physical activity: Epidemiological data show an increase in premature cardiovascular mortality with too much time spent sitting, a sedentary lifestyle or physical inactivity (with high risk) to moderate or vigorous activity (with low or reduced risk) of premature mortality. This continuum can be characterized as an exercise deficiency syndrome (Figure 1). Exercise deficiency syndrome: A synopsis. Regular exercise improves heart and lung function, reduces metabolic dysfunction, prevents certain types of cancer, reduces depression and increases cognitive function. There is also an increase in the quality of life and longevity.3,4 Most epidemiological studies on adequate physical activity show extensive cardiovascular benefits. This is also shown in the paper in this issue by Cheng et al.5 The authors report a meta-analysis of epidemiological studies relating to physical activity and cardiovascular mortality. The analysis consists of studies performed from 2004 to 2017. This represents a current update of recent studies on physical activity. The investigators addressed the dose–response relationship between the amount or intensity of activity and the corresponding decrease in cardiovascular mortality risk.5 Unlike many other studies and meta-analyses, Cheng et al.5 report a linear relationship between the reduction in risk of cardiovascular mortality and the level of activity. This finding is in sharp contrast with many previous studies3,6–9 with a typical non-linear relationship of dose–response and flattening of the curve with increasing intensity of activity, which is classified as vigorous. There are many explanations for this discrepancy. First, the authors compared moderate to low and vigorous intensity, but did not include the “zero” activity or phases of chronic inactivity as in most other studies. This explains the different and non-linear course of the dose–response relationship. The change from physical inactivity to low or moderate activity is the most important relative step and reveals the greatest and most significant effect regarding risk reduction.3,6,7 Thus, with this relationship, the dose–response curve will usually be non-linear. Second, the inclusion in the study of patients with cardiac diseases who were unable to exercise vigorously may be the reason for the small amount of data on vigorous activity. Another limitation of this meta-analysis is the examination of cardiovascular mortality without all-cause mortality. This may result in bias because cardiovascular mortality is more or less a soft endpoint, whereas all-cause mortality is a hard endpoint. Even short periods of activity are effective in reducing the risk of premature death from all-cause mortality and cardiovascular disease.7,10 Any physical activity is better than none.11 Exercise recommendations should consider non-linear or exponential curves. This means that low and moderate physical activity are the main goals for the prescription of preventive exercise.10 An increase in the level of activity may improve muscular endurance or fitness. However, for disease prevention, low or moderate activity sufficiently supports risk reduction and increased longevity. In addition, it may be more effective and realizable to prescribe moderate and everyday activities when counselling patients.12,13 Cheng et al. do not comment on prevention through physical activity in older patients. There are many studies, however, indicating that regular exercise by people older 65 years may reduce the risk of mortality risk.6,8 This is importance because improving physical fitness in older people enhances their quality of life and self-determination, especially when advancing into older age. It is never too late to start regular exercise. The most important question in this field of medicine is how to motivate people to adhere to regular exercise. Every doctor at each contact with a patient should ask about physical activity as the fifth vital sign. Even brief recommendations may be helpful to initiate a patient’s adherence to exercise. The Exercise Prescription for Health (www.efsma.eu) is an excellent approach to personalized medicine.9 Exercise prescription should be prescribed for outpatients as well for inpatients prior to discharge.12 The data in this report confirm the large and growing number of studies on the health benefits of physical activity14,15 and adds to the well-established knowledge that physical activity plays an important and significant part in preventive medicine, but is still limited in its implementation.4 All authors had have access to the data and critically revised the manuscript before submission. All authors have reviewed and approved this article prior to submission. The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article. HL is a cardiology consultant for European Space Agency and received speaker’s honoraria from Wörwag Co. and Univadis Co. TP reports no conflicts of interest. The author(s) received no financial support for the research, authorship, and/or publication of this article.