Background: No reviews have quantified the specific amounts of physical activity required for lower risks of coronary heart disease when assessing the dose-response relation. Instead, previous reviews have used qualitative estimates such as low, moderate, and high physical activity. Methods and Results: We performed an aggregate data meta-analysis of epidemiological studies investigating physical activity and primary prevention of CHD. We included prospective cohort studies published in English since 1995. After reviewing 3194 abstracts, we included 33 studies. We used random-effects generalized least squares spline models for trend estimation to derive pooled dose-response estimates. Among the 33 studies, 9 allowed quantitative estimates of leisure-time physical activity. Individuals who engaged in the equivalent of 150 min/wk of moderate-intensity leisure-time physical activity (minimum amount, 2008 US federal guidelines) had a 14% lower coronary heart disease risk (relative risk, 0.86; 95% confidence interval, 0.77 to 0.96) compared with those reporting no leisure-time physical activity. Those engaging in the equivalent of 300 min/wk of moderate-intensity leisure-time physical activity (2008 US federal guidelines for additional benefits) had a 20% (relative risk, 0.80; 95% confidence interval, 0.74 to 0.88) lower risk. At higher levels of physical activity, relative risks were modestly lower. People who were physically active at levels lower than the minimum recommended amount also had significantly lower risk of coronary heart disease. There was a significant interaction by sex ( P =0.03); the association was stronger among women than men. Conclusions: These findings provide quantitative data supporting US physical activity guidelines that stipulate that “some physical activity is better than none” and “additional benefits occur with more physical activity.”

Free radicals can cause lipid peroxidation and DNA damage, contributing to the development of cardiovascular disease (CVD) and cancer.^1-5 Vitamin E has antioxidant properties, including inhibition of oxidation of low-density lipoprotein cholesterol in plasma, leading to the hypothesis that it can prevent these chronic diseases.⁵ In some, but not all, basic research reports, vitamin E supplementation retarded atherogenesis.⁶ In descriptive data, investigators noted a strong inverse relation between plasma vitamin E concentrations and death rates from ischemic heart disease in men in several European countries.⁷ Additionally, several large cohort studies observed decreased CVD rates among individuals who self-selected for higher intakes of vitamin E through diet and/or supplements.^8-10 By 1997, despite a lack of randomized trials, 44% of US cardiologists reported routine use of antioxidant supplements, primarily vitamin E, compared with 42% who routinely used aspirin for the primary prevention of CVD.¹¹With regard to cancer, several observational studies, particularly case-control studies, also reported reduced rates of cancer among persons who self-selected for high antioxidant intakes.¹²

Objectives Physical inactivity is a risk factor for premature mortality and several non-communicable diseases. The purpose of this study was to estimate the global burden associated with physical inactivity, and to examine differences by country income and region. Methods Population-level, prevalence-based population attributable risks (PAR) were calculated for 168 countries to estimate how much disease could be averted if physical inactivity were eliminated. We calculated PARs (percentage of cases attributable to inactivity) for all-cause mortality, cardiovascular disease mortality and non-communicable diseases including coronary heart disease, stroke, hypertension, type 2 diabetes, dementia, depression and cancers of the bladder, breast, colon, endometrium, oesophagus, stomach and kidney. Results Globally, 7.2% and 7.6% of all-cause and cardiovascular disease deaths, respectively, are attributable to physical inactivity. The proportions of non-communicable diseases attributable to physical inactivity range from 1.6% for hypertension to 8.1% for dementia. There was an increasing gradient across income groups; PARs were more than double in high-income compared with low-income countries. However, 69% of total deaths and 74% of cardiovascular disease deaths associated with physical inactivity are occurring in middle-income countries, given their population size. Regional differences were also observed, with the PARs occurring in Latin America/Caribbean and high-income Western and Asia-Pacific countries, and the lowest burden occurring in Oceania and East/Southeast Asia. Conclusion The global burden associated with physical inactivity is substantial. The relative burden is greatest in high-income countries; however, the greatest number of people (absolute burden) affected by physical inactivity are living in middle-income countries given the size of their populations.

Wearable technologies, known as wearables, that can track a person’s physical activity behavior are popular consumer items with more than 125 million units shipped worldwide in 2017.¹ Such wearables, as well as smartphones, measure number of steps taken via an accelerometer within the device. Worldwide, the average number of steps accrued daily (measured by smartphones) is approximately 5000; in the United States it is 4800.² A common goal of 10 000 steps/d has been perpetuated by the lay press and is often used as the default by software programs on wearables and smartphones.^3,4 However, the origin of the goal of 10 000 steps per day is unclear. It likely derives from the trade name of a pedometer sold in 1965 by Yamasa Clock and Instrument Company in Japan called Manpo-kei, which translates to “10 000 steps meter” in Japanese.^5,6