| Abstract: | Introduction: Much of the attention on tobacco harm reduction has been on modifying the product, but the extent of modifying physical activity of smokers in reducing the harm is less known. Objectives: The objectives of this study are to find out whether becoming physically active could reduce the smoking hazards, and if so, the extent of benefits in each of the smoking related diseases. Methods: In this prospective cohort study, 429,244 individuals (47.9% men) went through standard medical screening program(s) from 1996 to 2008, withan average follow up of 8.05 (SD: 4.21) years.The exercise volume of each individual, expressed in MET hour/week, was placed into inactive (3.75), low-active (3.75–7.49), or active (7.50) category. Hazard ratios (HR) for cardio-vascular disease (CVD) mortality, adjusted for 10 confounders, were calculated. Results: Smokers were found to exercise less (22.9%) than ex-smokers (37.4%) and non-smokers (24.2%). When compared to inactive smokers, low-active or active smokers had significantly lower CVD mortality risk, 0.85 (0.68~1.06) and 0.66 (0.54–0.79) respectively. If smokers quit, their all-cause mortality risks further decreased to 0.53 (0.43–0.66) for active ex-smokers. For ischemic heart disease and stroke mortality, physical activity and quit smoking can also significantly lower the mortality risk. Conclusion: Physical activity reduced mortality risks of smokers for CVD, including ischemic heart disease and stroke, by 34%, by 48% and by 27%, respectively, in contrast to quitting smoking by ex-smokers, 47%, 49% and 51%. In addition, increasing exercise made smokers more likely to quit, resulting in ex-smokers, with a major reduction in mortality. |
