Abstract
Background. In 487 elderly women aged 65-77 years, we examined the association of smoking with physical performance measures of muscle function and whether the effect of smoking on physical performance measures is mediated through its effect on vitamin D or estrogen metabolism. Methods. Timed rise, timed walk at normal and fast speed, grip strength, and serum biochemical measurements were compared between smokers, past smokers, and nonsmokers. Analysis of covariance was used to compare physical performance variables while adjusting for confounding variables. Results. Compared to nonsmokers and past smokers, current smokers were significantly (p <.05) slower on timed rise and timed walk tests and had decreased grip strength. From multivariate analysis, smoking, age, total body fat, and serum 1,25(OH)2D examined as quartiles were predictors of physical performance measures. The effect of current smoking on physical performance was equivalent to a normal age-related decline in physical performance tests of 7-11 years depending on the test. Conclusions. The results of this study suggest that current smoking is a risk factor for decreased muscle strength leading to decreased physical performance in elderly women. The effect of smoking on physical performance is in part mediated by its effect on 1,25(OH)2D metabolism. Smoking may also have an independent effect on physical performance possibly by a direct effect on muscle or through an effect on vascular function.