Cigarette Smoking Impairs Cardiorespiratory and Metabolic Response at Peak Incremental Exercise and during Recovery in Young, Physically Active Adults

Purpose: Cigarette smoking (CS) induces systemic changes that impair cardiorespiratory and muscular function both at rest and during exercise. Although these abnormalities are reported in sedentary, middle-aged smokers (SM) with pulmonary disease, few and controversial studies focused on young, physically active SM at the early stage of smoking history. This study aimed at assessing the impact CS on cardiorespiratory and metabolic response during an incremental test and the subsequent recovery in young, physically active SM without known lung or cardiovascular disease. Methods: After pulmonary function evaluation, 12 SM (age: 22±2 yr; body mass: 75±8 kg; stature: 1.78±0.06 m; 12±4 cigarette/day for 6±2 years; mean±SD) and 12 non-smokers (CTRL; age: 23±1 yr; body mass: 76±8 kg; stature: 1.79±0.08 m) matched for age and exercise habits, underwent an exhaustive incremental step test (25 W/2 min) on a cycle ergometer. Pulmonary O2 uptake (V’O2), expiratory ventilation (V’E), heart rate (fH) responses and lactate concentration were assessed during the test and subsequent recovery. Results: Despite similar static lung volumes, SM reported lower peak expiratory flow (-23%; P = 0.003) and maximal voluntary ventilation (-10%; P = 0.003). At submaximal exercise, no differences in the cardiorespiratory and metabolic were noted between the two groups. However, SM exhibited ventilatory (P < 0.01) and lactate thresholds at lower work rates (P = 0.01). At peak exercise, SM exhibited lower V’O2 (-8%; P = 0.02), mechanical power (-11%; P = 0.02) and V’E (-9%; P = 0.01). During recovery, SM showed longer time constants (τ) in V’O2 (+52%; P = 0.002), V’E (+19%; P = 0.027) and fH (+21%; P = 0.022) and smaller fH at 30 s of recovery (HRR30; -31%; P = 0.032). Conclusions: These results are compatible with an early CS-related impairment of the cardiorespiratory and metabolic function even in young individuals with relatively short smoking history.