Persistent physical activity translating to persistent reduction in mortality

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.1 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.2–5 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.1,6 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),1,6 even suggesting that CRF should become a vital sign for clinical practices.7 Although PA is extremely important, substantial data suggest that CRF predicts prognosis even more so than does PA.8,9 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.6 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.10 In a study of 14,345 subjects from the Aerobics Center Longitudinal Study (ACLS) followed for 11.4 years, Lee et al.11 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.12,13 In this issue of the European Journal of Preventive Cardiology, Schnohr and colleagues14 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 the population to increase LTPA and maintain this active lifestyle throughout their lifespan for the prevention of CVD, especially CHD mortality. Like the CCHS, which has also published on the benefits of running, which is considered to be one of the most popular and beneficial forms of LTPA, we have also published many papers on the benefits of running.15–18 An analysis of 55,000 from the ACLS, including 13,000 runners and 42,000 non-runners followed on average for 15 years, Lee and colleagues15 demonstrated that runners had impressive reductions in all-cause and CVD mortality of 30% and 45%, respectively, extending life by 3 years and CVD life by 4.5 years, respectively. Like the current study from the CCHS, persistent runners had the greatest benefit, whereas those who began running but later stopped or vice versa had almost half of the benefit compared with never runners. However, we also showed that maximal benefit appeared to occur at very low levels of running (e.g. <6 miles/week, one to two times per week and <51 minutes per week), whereas the very greatest runners seemed to have a loss of benefit and potentially slight harm compared to lower level runners.16–18 We think that these results certainly suggest that at the highest level of PA, ‘more was not better’ and raises the possibility that ‘more may be worse’. However, running is considered a fairly intense form of LTPA, and these effects may not be applicable to lower intensities of LTPA. Certainly, the constellation of evidence that persistent PA performed throughout life is associated with profound health benefits is supported by the current paper by Schnohr and colleagues.14 In addition, we believe that high intensity PA that increases heart rate and better increases levels of CRF is probably superior to low intensity PA for overall health effects.19,20 However, the major public health challenge is getting people to increase PA in the first place, especially LTPA, throughout their life, which is a cost-effective strategy that must be promoted throughout the healthcare industry.1,6,21–24 Indeed, the future health of the USA, Europe and much of the globe depends on these efforts. The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. The author(s) received no financial support for the research, authorship, and/or publication of this article.