Smoking as a confounding factor on the influence of cold therapy on the vascular endothelium function of young men

[Purpose] This study was designed to determine whether smoking affects endothelium function after cold therapy in young men. [Subjects] The final cohort included 27 healthy men (age, 20-21 years). Because an impact on vascular endothelium function was anticipated to be caused by smoking, the study enrolled 14 participants in a smoking group and 13 in a non-smoking group. [Methods] Vascular endothelial function was assessed by determining the reactive hyperemia index (RHI), using finger-tonometry. RHI was measured twice, at rest (baseline) and after a cold stimulus. The forearm was cooled with an ice bag for 10 min as the cold stimulus. Comparisons between the RHI at baseline and after cold treatment, and between the smoking and non-smoking groups, were performed using the paired and unpaired t-tests, respectively. [Results] There was a significant difference in baseline RHI values between the smoking and non-smoking groups, but there was no significant difference between the baseline and post-treatment RHI values in either group. [Conclusion] These results suggest that cigarette smoking damages the endothelial cells in young men with a short history of smoking. However, cold therapy did not have a significant impact on the RHI in either group.