Nicotine, a major toxic component of cigarette smoke, together with carbon monoxide (CO), constitutes a significant environmental exposure with systemic effects. Beyond its addictive potential, chronic nicotine exposure may induce inflammation, oxidative stress, tissue hypoxia, and autonomic imbalance, potentially impairing respiratory muscle strength, functional capacity, and overall physical performance. Additionally, nicotine dependence has been associated with sleep disturbances, cognitive dysfunction, altered pain perception, and reduced quality of life.
Although previous studies have examined individual effects of smoking on specific health outcomes, research addressing these multidimensional impacts within a comprehensive framework remains limited. Therefore, this study aims to investigate the relationship between nicotine dependence level and respiratory muscle strength, functional capacity, cognitive functions, pain, quality of life, physical activity level, and sleep quality, in order to provide a more holistic understanding of the clinical consequences of nicotine dependence.