Tobacco smoke is probably the single most significant source of toxic chemicals that humans are exposed to. Smoking is associated with a variety of pathological conditions such as cardiovascular and pulmonary diseases. In addition to the known harmful effects of cigarette smoking, several epidemiological studies identified tobacco use as a risk factor for sarcopenia, the loss of skeletal muscle mass and strength with advancing age. Previous studies examined skeletal muscles of smokers in comparison with muscles of non-smokers and found structural and metabolic damage in muscles of smokers.

Quitting of smoking is known to be associated with weight gain. A previous study examined the effects of smoking cessation on body composition of post-menopausal women using dual-energy x-ray absorptiometry (DEXA). It was found that women who successfully quit smoking for a period of 16 months have significantly increased their body weight, fat mass, muscle mass and functional muscle mass in comparison with non-quitters women. For the first time, it was shown that smoking cessation is associated with an increase of functional muscle mass. Yet, the effects of quitting of smoking on muscle mass and muscle functional capabilities of younger subjects remain unclear. Therefore, we aim to investigate the effects of smoking cessation on muscle mass, muscle function and strength in heavy smoker's subjects. Our findings may shed light on the beneficial effects of smoking cessation regarding the status and function of skeletal muscle in heavy smokers and as a possible strategy to prevent or delay the progression of sarcopenia.

Research hypothesis: Smoking cessation among adult heavy smokers will lead to increase in skeletal muscle mass and improvement of muscle function and strength compared with continued smokers.

Body composition and muscle function were assessed at the beginning of a smoking cessation program and again after 12 months. Changes in body composition and muscle function were compared between continued smokers and quitters.

Inclusion Criteria:

• Healthy men and women between the ages of 18-65
• Heavy smokers (smoking more than 15 cigarettes per day)
• Taking part in smoking cessation support group at "Clalit Health Services", Haifa and Western Galilee district

Exclusion Criteria:

• Medical conditions affecting skeletal muscle metabolism or function.
• Use of corticosteroids or any other medication or nutritional supplement affecting skeletal muscle
• Consuming more than two alcoholic drinks per day

Subjects were recruited from support groups of smoking cessation conducted at "Clalit Health Services" at Haifa and Western Galilee district.