Effects of abstinence from cigarette smoking on the cardiorespiratory capacity

The purpose of this study was to determine the effect of 6 or 7 d of abstinence from cigarette smoking on the cardiorespiratory capacity of young men. The subjects were 11 male volunteers, mean age 20.5 yr. Their mean smoking duration and cigarettes smoked per day were about 3.5 yr and 20.5 cigarettes, respectively. On the first day of the study, the subjects' physical characteristics, pulmonary functions, and maximal oxygen debt predicted by bicycle ergometer exercise were measured. The subjects' heart rate at rest (HRrest), blood pressure, venous blood analysis and maximal oxygen intake (VO2max) in a treadmill exercise test were measured on the second day. From the time of the second-day measurements, the subjects abstained from cigarette smoking. On the eighth and ninth days of the study, the same measurements were taken as the measurements of the first and second days, respectively. The changes between before and after abstinence from smoking were as follows. The plasma cotinine had almost disappeared after the 7 d of abstinence from smoking. Pulmonary functions did not show a significant improvement. Although there were no significant changes in the HRrest or systolic or diastolic blood pressure, the pulse pressure was significantly increased (P < 0.05). Although the blood components were not changed significantly, the PO2, O2 saturation, HCO3, and CO2 concentration were significantly increased. The predicted maximal oxygen debt was not significantly decreased. Although the VO2max and maximal ventilation volume were not changed, the exercise time was significantly prolonged (P < 0.001). The heart rate during the treadmill exercise at almost all stages decreased significantly; however, the maximal heart rate did not change. In conclusion, exercise performance was improved by the 7 d of abstinence from smoking.