Relationships between exercise, smoking habit and mortality in more than 100,000 adults

Exercise is associated with reduced risks of all-cause, cardiovascular disease (CVD) and cancer mortality; however, the benefits in smokers and ex-smokers are unclear. The aim of this study was to investigate associations between exercise, smoking habit and mortality. Self-reported exercise and smoking, and all-cause, CVD and cancer mortality were assessed in 106,341 adults in the Health Survey for England and the Scottish Health Survey. There were 9149 deaths from all causes, 2839 from CVD and 2634 from cancer during 999,948 person-years of follow-up. Greater amounts of exercise were associated with decreases and greater amounts of smoking were associated with increases in the risks of mortality from all causes, CVD and cancer. There was no statistically significant evidence of biological interaction; rather, the relative risks of all-cause mortality were additive. In the subgroup of 26,768 ex-smokers, the all-cause mortality hazard ratio was 0.70 (95% CI 0.60, 0.80), the CVD mortality hazard ratio was 0.71 (0.55, 092) and the cancer mortality hazard ratio was 0.66 (0.52, 0.84) in those who exercised compared to those who did not. In the subgroup of 28,440 smokers, the all-cause mortality hazard ratio was 0.69 (0.57, 0.83), the CVD mortality hazard ratio was 0.66 (0.45, 0.96) and the cancer mortality hazard ratio was 0.69 (0.51, 0.94) in those who exercised compared to those who did not. Given that an outright ban is unlikely, this study is important because it suggests exercise reduces the risks of all-cause, CVD and cancer mortality by around 30% in smokers and ex-smokers.