Impact of cigarette smoking on cardiovascular function following high-intensity interval exercise in physically active smokers.

PURPOSE: This study examines the effects of cigarette smoking (CS) on post-exercise cardiovascular re-stabilization following high-intensity interval exercise (HIIE) in physically active smokers. METHODS: Fifteen physically active male smokers completed three conditions, including the CS, sham smoking (SS), and non-smoking (NS) in a randomized crossover design. In each condition, participants performed 20 mins of HIIE followed by one of the assigned smoking conditions. Cardiovascular function indices such as heat rate (HR) heart rate variability (HRV), brachial-ankle pulse wave velocity (baPWV), ankle-brachial index (ABI), peripheral oxygen saturation (SpO2), blood lactate concentration (BLa), and perceived recovery scale (PRS) were evaluated at baseline, immediately post-exercise, post-smoking, and 45 min post-exercise, whereas endothelial function (flow-mediated dilation, FMD) was assessed at baseline and 45 min of post-exercise. RESULTS: Significant interaction effects were observed for HR (p<0.001, ES (effect size, partial eta squared) = 0.11), HRV indices (lnLF: p=0.009, ES =0.21; lnHF: p=0.001, ES = 0.23), FMD (p<0.001, ES =0.22), and SpO₂ (p=0.018, ES = 0.22). The CS condition showed delayed HR and HRV recoveries compared with the SS and NS conditions. FMD was significantly lower in both the CS and SS conditions than in the NS condition, with a greater reduction observed in the CS condition. SpO2 returned to baseline levels 45 min post-exercise in the NS condition, showed a trend toward recovery toward baseline in the SS condition, and did not significantly recover to baseline in the CS condition. baPWV, ABI, BLa, and PRS showed no significant differences among conditions. CONCLUSION: CS delayed post-HIIE recovery of HR and HRV (lnLF, lnHF), impaired endothelial function and delayed SpO2 restauration. Therefore, avoiding CS immediately after HIIE may help preserve normal post-exercise cardiovascular early recovery after HIIE in physically active smokers.