Persistent physical activity translating to persistent reduction in mortality

TL;DR: It is demonstrated that persistent PA in this generation improves the metabolic health and body composition of both mothers and future generations, and future studies with more comprehensive longitudinal data analyses could provide even greater health benefits of PA on CHD and mortality.

Abstract: Cardiovascular disease (CVD) and, particularly, coronary heart disease (CHD) remain the leading causes of death in the United States and most of the developed countries. The prevalence of overweight and obesity has also been increasing across most of the globe, with a striking increase in severe or ‘morbid’ obesity, now reaching almost 8% of the adult US population. It has been well known for many decades that physical activity (PA) and exercise provide substantial benefits for the prevention of obesity, as well as overall health, functional capability, quality of life and longevity. My colleagues and I have published extensively, not only on the benefits of PA, but especially on the benefits of having high levels of cardiorespiratory fitness (CRF), even suggesting that CRF should become a vital sign for clinical practices. Although PA is extremely important, substantial data suggest that CRF predicts prognosis even more so than does PA. However, although a component of CRF may be genetic or inherited, the major part of CRF is derived from persistent and effective PA and exercise training. In fact, each metabolic equivalent (MET) increase in CRF is associated with 13% and 15% reductions in all-cause mortality and in CVD/CHD events, respectively, in a major meta-analysis. In a study of 14,345 subjects from the Aerobics Center Longitudinal Study (ACLS) followed for 11.4 years, Lee et al. demonstrated that every 1 MET increase in CRF over time assessed in fitness examinations separated by an average of 6.3 years was associated with reductions in all-cause and CVD mortality of 15% and 19%, respectively. Futhermore, in the fitness versus fatness debate, these improvements persisted even after adjusting for changes in body mass index. Moreover, we have shown that persistent PA in this generation improves the metabolic health and body composition of both mothers and future generations. In this issue of the European Journal of Preventive Cardiology, Schnohr and colleagues prospectively studied 12,314 healthy subjects followed up to 33 years in the Copenhagen City Heart Study (CCHS) with at least two repeated measures of PA, and demonstrated that persistent leisure time physical activity (LTPA) compared to sedentary activity was associated with nearly 50% reductions in CHD mortality, with differences in mortality for light, moderate, and high LTPA being 2.8 years, 4.5 years, and 5.5 years, respectively. An increase in LTPA over time was associated with 2.4 years of longer life, whereas substantial decreases in LTPA was associated with 4.2 years shorter life, respectively. These findings, however, should be interpreted with some caution. Changes (persistence and non-persistence) in PA in this study was defined based on the levels of PA in at least two out of four consecutive examinations between 1976 and 2003 over 27 years. Therefore, there could be, for example, participants classified in the ‘sedentary’ group who were sedentary only in the first two examinations, but ‘light’, ‘moderate’, or ‘high’ activity in the following examinations, and vice versa. In these cases, participants in the ‘sedentary’ group are not completely sedentary, and participants in the ‘high’ active group are not completely highly active. Similar limitations exist in non-persistent PA over time, e.g. participants in the substantial and small ‘decrease’ groups could have decreased their PA levels between the first two examinations, but increased or had no change in the following examinations. These limitations in the classification of changes in PA over time could potentially underestimate the true effects of PA on CHD and mortality in relative risk estimations. Therefore, future studies with more comprehensive longitudinal data analyses could provide even greater health benefits of PA on CHD and mortality. Nevertheless, these data certainly add to the body of evidence supporting the recommendation for