1 Purpose: This study examined post-exercise inflammatory and leukocyte responses in 2 smokers and non-smokers, as well as the effects of cigarette smoking on the acute post-3 exercise inflammatory and leukocyte response in habitual smokers. Method: Eleven, 4 recreationally-active, male smokers and eleven non-smokers, matched for age and aerobic 5 fitness (23.2±3.04 & 24.0±2.41 years and 36.9±7.95 & 36.4±7.12 mL.kg -1 .min -1 VO2peak 6 respectively) were familiarized and underwent baseline

more »

... ss testing. Participants then 7 completed 40 min of cycling at 50% peak aerobic workload. Smokers performed two 8 randomized exercise sessions, including an acute post-exercise smoking (two cigarettes in 15 9 min of 12 mg tar and 1 mg nicotine) and no-smoking condition, while non-smokers 10 performed one exercise session without smoking. Venous blood was obtained pre-and post-11 exercise for analysis of interleukin (IL)-6, IL-1receptor antagonist (ra), tumor necrosis factor-12 alpha (TNF-α) and c-reactive protein (CRP). Results: No differences existed between groups 13 for resting CRP (d= 0.25-0.46; p=0.374-0.617). Despite no baseline difference (d= 0.03-0.07; 14 p=0.149), exercise-induced increases were observed for IL-1ra in smokers (d=0.50; p=0.024-15 0.033), which was not observed in the never-smoker group. No between-group difference 16 was observed for IL-6 across all points (d=0.09-0.5; p=0.102-0.728); however, all groups 17 observed significant within-group change (d=0.27-1.09; p=0.001-0.042). Further, TNF-α for 18 smokers-smoking was elevated above both smokers-no smoking and non-smokers at baseline 19 (SNS) and across the protocol (d=1.20-1.80; d=0.20-1.0; p=0.001-0.035). Additionally, a 20 marked post-exercise increase in leukocyte and neutrophil concentrations was evident in 21 smokers-smoking compared to non-smokers and smokers-no smoking as indicated by a 22 moderate to large effect size (d=0.72; d=0.78). Conclusion: Consequently, male smokers 23 exhibit an altered post-exercise pro-inflammatory profile compared to age and fitness-24 matched non-smokers. 25 2