Accumulating evidence supports the concept that low socioeconomic status (SES) is emerging as a contributor to all-cause mortality and cardiovascular risk and that it is equivalent to traditional risk factors. 1 This increased cardiovascular disease (CVD) risk may be mediated by behavioral, psychological, social and biological risk factors that are more prevalent in low SES individuals, and even disparities in standards of patient care. 1,2 Increased cardiorespiratory fitness (CRF) has been shown to lower CVD risk and all-cause mortality independent of other risk factors, race and gender in high-risk populations. 3 Relatively lower levels of leisure time physical activity and CRF have been reported in low SES individuals as compared with those of high SES groups. 4 Previous studies have also reported that the low CRF levels in low SES individuals could in part explain the socioeconomic disparities in all-cause mortality. 5,6 Low leisure time physical activity may be fostered by lack of resources in socioeconomically deprived neighborhoods, such as the absence of sidewalks, fewer accessible recreational facilities, relatively unsafe outdoor exercise environments and reduced opportunities to engage in leisure time physical activity. 7 Longitudinal studies have demonstrated that neighborhoods with favorable physical activity environments are associated with increased individual and group physical activities and better cardiovascular risk profiles. 8,9 This suggests that the lower levels of physical activity observed among low SES groups is in part due to the built environment. By extension, the worse cardiovascular outcomes and higher mortality among lower SES groups may well be due in part to these environmental factors. In the study by Jae et al. 10 published in the current issue, the investigators sought to assess the independent and combined effects of CRF and SES in 2368 men, participants in the Kuopio Ischaemic Heart Disease Risk study. SES was determined by self-reported questionnaires by way of a summary index that combined measures of income, education, occupational prestige, material standard of living, and housing conditions. CRF was based on directly measured oxygen uptake (VO 2peak ), the most objective marker of CRF. Blood pressure, glucose and lipid levels, and body mass index were assessed.Risk factors including smoking, the presence of chronic disease, medications, and related demographic/lifestyle information were evaluated by standardized selfadministered questionnaires. Physical activity levels and estimated caloric expenditure (kcal/day) were also assessed using a 12-month physical activity history modified from the Minnesota leisure-time physical activity questionnaire. Although the investigators did not elaborate on the relevance of the latter data, it would have been of interest to do so.SES was inversely and independently associated with risks of all-cause mortality and CVD mortality. Directly measured peak oxygen uptake among low SES individuals was approximately 3.8 ml/kg/min lower compare...