Cigarette smoking slows the on- and the off- cardiorespiratory and gas-exchange kinetics during moderate exercise in young, physically active adults

Purpose Cigarette smoking (CS) impact on cardiopulmonary function has been extensively investigated on sedentary, middle-aged smokers (SMK) with pulmonary disease, but not on young SMK with high fitness level. This study evaluated the cardiopulmonary and gas-exchange kinetics during and after moderate exercise in young, physically active SM without known diseases. Methods Ten SMK (age: 21 +/- 2 year., body mass: 78 +/- 6 kg; stature: 1.79 +/- 0.07 m; 12 +/- 5 cigarette/day for 6 +/- 2 year.; mean +/- SD) and twelve non-smokers (CTRL; age: 24 +/- 3 year, body mass: 78 +/- 9 kg; stature: 1.80 +/- 0.08 m) matched also for exercise habits performed an incremental cycloergometric test to assess maximum pulmonary oxygen uptake (V'O2max) and first ventilatory threshold (VT1). After pulmonary evaluation, participants performed four 6-min moderate-intensity tests at 90% VT1. The time constant (tau) of the on- and off-phases were determined for expiratory ventilation (V'E), V'O2, heart rate (fH) and cardiac output (Q'). Results Despite similar static lung volumes, SMK exhibited lower peak expiratory flow (-21%; P = 0.009) and maximal voluntary ventilation (-12%; P = 0.008). SMK had lower V'O2max (3657 +/- 325 vs. 3397 +/- 316 ml/min for CTRL and SMK, respectively; P = 0.009) and mechanical power at VT1 (201 +/- 26 vs. 185 +/- 16 W for CTRL and SMK respectively; P = 0.041). In on-phase, SMK demonstrated longer tau in Q' (+ 22%; P = 0.032), fH (+ 56%; P = 0.005), V'O2 (+ 41%; P = 0.032), V'E (+ 47%; P = 0.007). In off-phase, tau in SMK was lengthened for Q' (+ 51%; P = 0.041, fH (+ 42%; P = 0.022), V'O2 (+ 20%; P = 0.002) and V'E (+ 42%; P = 0.018). Conclusion CS slowed cardiopulmonary and gas-exchange kinetics at moderate exercise even in young individuals with short smoking history.