A new study suggests that long term heavy tobacco smoking can lead to potentially harmful structural and functional changes in skeletal muscles outside the lungs, even in smokers who don't have chronic obstructive pulmonary disease.
Smoking is the major cause of COPD, but relatively little is known about the effect of smoking on skeletal muscles. Skeletal muscles are striated and usually attached to the skeleton. By exerting force on the bones and joints, the skeletal muscles contract to produce movement.
Dr. Maria Montes de Oca from Hospital Universitario de Caracas, Venezuela, and colleagues compared the vastus lateralis muscle, which originates in the thigh bone extends to the shin bone, in 14 heavy smokers without COPD and 20 healthy non-smokers. Subjects in both groups led sedentary lifestyles.
According to their report, published in the medical journal, Chest, the investigators observed significantly reduced cross sectional area of two types of muscle fibers in smokers compared with non-smokers.
The investigators note that smokers were also more apt to show potentially harmful metabolic changes including an imbalance of oxidant and antioxidant chemicals, suggesting preferential damage of oxidative fibers among smokers.
The results also suggest that tobacco smoke alters the normal process by which the body generates nitric oxide, a chemical that helps open small blood vessels. This alteration could lead to hypoxia (low oxygen levels), which in turn may explain the fiber atrophy observed in the smokers.
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