Smoking-Suppressed Heart Rate Recovery in Young Male College Students Who Regularly Exercised.

Smoking is a major risk factor of several types of cancer and cardiovascular disease (1). According to WHO report, every year, approximately 6 million people worldwide die of heart diseases, lung cancer, or other diseases associated with tobacco smoking. If this trend continues, 8 million people are estimated to die every year by 2030 (2). From this perspective, smoking is obviously a serious health-related issue. Regular exercise is recommended for the prevention of coronary heart diseases , as it counterbalances the prevalence of these diseases (3). Heart rate response and coronary heart disease are highly correlated (4). Delayed heart rate recovery (HR R) after exercise is considered as a predictive indicator of coronary heart disease (5). Moreover, HR R after exercise is faster among healthy people who exercise regularly than among people who do not exercise (6). In particular , HR R in smokers is often delayed (7). As such, regular exercise and smoking are considered to affect the HR R after exercise, but the effect of smoking on the time to HR R in individuals who exercise regularly has not been clarified yet. This study aimed to investigate the HR R rate after exercise according to smoking status in healthy college male students who regularly exercised. Participants were categorized into either a non-smoker group (n = 24) or a smoker group (n = 19). Those who had been smoking 10 cigarettes per day for more than 5 years were categorized as smokers. The mean  standard deviation age of the patients in the nonsmoker and smoker groups were 20.5 ± 2.7 and 21.5 ± 2.3 years, respectively, without any significant difference (t = −0.874, P = 0.393). The participants in this study were healthy people who regularly exercised at least 3 times a week and had no history of disease or cardiac malfunction (dysfunction) on resting electrocardiog-raphy. In a treadmill exercise test (graded exercise test) using the Bruce protocol (8), VO 2 max (mLkgmin) and heart rate (bpm) were determined. HR R was assessed at 20 (HRR 20), 40 (HRR 40), 60 (HRR 60), and 80 seconds (HRR 80) after exercise. Decreasing heart rate (%) was calculated by dividing it by the maximum heart rate (HRmax). Statistical verification was performed by performing an independent t test by using SPSS 19.0 (IBM, Armonk, NY, USA). Statistical significance was set at P < 0.05. The resting heart rate in the nonsmoker …