EFFECT OF CIGARETTE SMOKING ON CARDIORESPIRATORY AND METABOLIC RESPONSE TO DIFFERENT PROTOCOLS IN YOUNG ACTIVE MALES

Cigarette smoking is one of the most impacting risk factors for cardiopulmonary morbidity and a major cause of mortality. It leads to systemic modifications that alter the cardiorespiratory and metabolic response at rest and during exercise. Indeed, stimulates the sympathetic nervous system, elevating the heart rate (HR) and cardiac work. Likewise, tar impairs O2 diffusion across the alveolar-capillary barrier, and carbon monoxide reduces O2 transport and extraction. The analysis of the cardiorespiratory and metabolic transitions at different work rates can provide insights in the O2 transport and delivery mechanisms. Hence, this dissertation aimed to provide a comprehensive examination of the effect of cigarette smoking on the cardiorespiratory and metabolic responses to exercise in young, physically active males. The smokers, compared to a no-smoker group, were evaluated in different exercise protocols: i) moderate intensity square-wave work rates to assess the cardiorespiratory and metabolic kinetics; ii) incremental stepwise protocols to determine the maximum oxygen uptake (V ̇_(O_2 max)), a benchmark for cardiorespiratory fitness, recovery kinetics, and exercise capacity; iii) moderate and iv) heavy intensity sinusoidal work rates. Cigarette smoking has detrimental effects on cardiorespiratory and metabolic response to different exercise protocols in young, physically active males. Despite young age, high fitness level and similar pulmonary function, the smokers were characterized by slower cardiorespiratory and metabolic kinetics during moderate exercise and during the recovery of an incremental test. Interestingly, there were no differences between the smokers and controls during both sinusoidal exercises, except for a shorter time to exhaustion that may suggest peripheral dysfunction.