Skeletal muscle morphology, metabolism and function in smokers and non‐smokers. A study on smoking‐discordant monozygous twins

Publisher Website
Google Scholar
Abstract
Whether differences in skeletal muscle [vastus lateralis] characteristics between smokers and non-smokers have a genetic background was studied using 6 pairs of smoking-discordant monozygous twins. The percentage type I fibers was lower in the smokers, who also had smaller diameters of this fiber type. Cytochrome oxidase activity was decreased in the smokers. No differences were seen for other enzymes of energy metabolism, capillary density, isometric or dynamic strength, or short-term muscular endurance. The non-smokers tended to be more physically active. In 4 ex-smoker/non-smoker pairs, no significant differences were found for the investigated parameters. The difference in fiber type distribution is not due to a hereditary predisposition to take up smoking. The small difference in physical activity is an unlikely cause. Thus, smoking per se appears to be the most plausible explanation for the difference in fiber type distribution and associated muscle characteristics. No definitive conclusion regarding the reversibility of the smoking-related differences can be drawn from the present results.