Relationship of Leisure-Time Physical Activity and Mortality
Urho M. Kujala, MD; Jaakko Kaprio, MD; Seppo Sarna, PhD; Markku Koskenvuo, MDContext.— Physical activity and fitness are believed to reduce premature mor-tality, but whether genetic factors modify this effect is not known.Objective.— To investigate leisure physical activity and mortality with respect tofamilial aggregation of health habits during childhood and factors that may enablesome individuals to achieve higher levels of fitness.Design.— Prospective twin cohort study.Setting.— Finland.Subjects.— In 1975, at baseline, 7925 healthy men and 7977 healthy women ofthe Finnish Twin Cohort aged 25 to 64 years who responded to a questionnaire onphysical activity habits and known predictors of mortality. Those who reported ex-ercising at least 6 times per month with an intensity corresponding to at least vig-orous walking for a mean duration of 30 minutes were classified as conditioningexercisers, those who reported no leisure physical activity were classified as sed-entary, and other subjects were classified as occasional exercisers.Main Outcome Measures.— All-cause mortality and discordant deaths amongsame-sex twin pairs from 1977 through 1994.Results.— Among the entire cohort, 1253 subjects died. The hazard ratio fordeath adjusted for age and sex was 0.71 (95% confidence interval [CI], 0.62-0.81)in occasional exercisers and 0.57 (95% CI, 0.45-0.74) in conditioning exercisers,comparedwiththosewhoweresedentary(Pfortrend ,.001).Amongthetwinpairswho were healthy at baseline and discordant for death (n=434), the odds ratio fordeath was 0.66 (95% CI, 0.46-0.94) in occasional exercisers and 0.44 (95% CI,0.23-0.83) in conditioning exercisers compared with those who were sedentary (Pfor trend, .005). The beneficial effect of physical activity remained after controllingfor other predictors of mortality.Conclusion.— Leisure-time physical activity is associated with reduced mortal-ity, even after genetic and other familial factors are taken into account.