title: Time-dependent relation between smoking cessation and improved exercise tolerance in apparently healthy middle-age men and women.
abstract: BACKGROUND
  Smoking is an independent cardiovascular risk factor and correlates with reduced exercise tolerance. However, data on the time dependent effect of smoking cessation on exercise tolerance are limited.
  
  
  METHODS
  We investigated 17,115 men and women who were annually screened at the Institute for Medical Screening of the Chaim Sheba Medical Centre. All subjects had their smoking status documented and performed an exercise stress testing (EST) according to Bruce protocol at each visit. Subjects were divided at baseline into four groups: active smokers (N = 2858), recent quitters (smoking cessation ≤2 years before baseline EST; N = 861), remote quitters (smoking cessation >2 years before the baseline EST; N = 3856) and never smokers (N = 9810). Baseline and follow up EST duration were compared among the four groups.
  
  
  RESULTS
  Recent quitters demonstrated a 2.4-fold improvement in their EST duration compared with active smokers (improvement of 24 ± 157 vs. 10 ± 157 s, respectively, p = 0.02). Multivariate logistic regression showed that recent quitters were 26% more likely to improve their exercise tolerance compared with active smokers (95% confidence interval (CI) 1.08-1.47, p = 0.003). Assessing smoking status as a time-dependent covariate during four consecutive visits demonstrated that recent quitters were 17% more likely to improve their exercise tolerance compared with active smokers (95% CI 1.02-1.34, p = 0.02), with a less pronounced benefit among remote quitters (hazard ratio = 1.11, 95% CI 1.02-1.21; p = 0.01).
  
  
  CONCLUSIONS
  Smoking cessation is independently associated with improved exercise tolerance. The benefits of smoking cessation are evident within the first two years of abstinence.
authors.affiliation: Leviev Heart Institute, Sheba Medical Centre, Israel.
authors.forename: Anat
authors.initials: A
authors.lastname: Berkovitch
authors.affiliation: Department of Internal Medicine C, Sheba Medical Centre, Israel Pinchas Borenstein Talpiot Medical Leadership Program, Sheba Medical Centre, Israel Sackler School of Medicine, Tel-Aviv University, Israel.
authors.forename: Shaye
authors.initials: S
authors.lastname: Kivity
authors.affiliation: Leviev Heart Institute, Sheba Medical Centre, Israel Sackler School of Medicine, Tel-Aviv University, Israel.
authors.forename: Robert
authors.initials: R
authors.lastname: Klempfner
authors.affiliation: Institute for Medical Screening, Sheba Medical Centre, Israel.
authors.forename: Shlomo
authors.initials: S
authors.lastname: Segev
authors.affiliation: Leviev Heart Institute, Sheba Medical Centre, Israel Department of Internal Medicine 'E', Tel-Aviv Medical Centre, Israel.
authors.forename: Assi
authors.initials: A
authors.lastname: Milwidsky
authors.affiliation: Leviev Heart Institute, Sheba Medical Centre, Israel Sackler School of Medicine, Tel-Aviv University, Israel.
authors.forename: Ilan
authors.initials: I
authors.lastname: Goldenberg
authors.affiliation: Department of Internal Medicine C, Sheba Medical Centre, Israel Sackler School of Medicine, Tel-Aviv University, Israel.
authors.forename: Yechezkel
authors.initials: Y
authors.lastname: Sidi
authors.affiliation: Leviev Heart Institute, Sheba Medical Centre, Israel Pinchas Borenstein Talpiot Medical Leadership Program, Sheba Medical Centre, Israel Elad.Maor@sheba.health.gov.il.
authors.forename: Elad
authors.initials: E
authors.lastname: Maor
mesh_terms: D000328:Adult; D001794:Blood Pressure; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006304:Health Status; D006339:Heart Rate; D006801:Humans; D007557:Israel; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D010809:Physical Fitness; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D020127:Recovery of Function; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects / Q000503:physiopathology; D016540:Smoking Cessation; D000074606:Smoking Prevention; D013997:Time Factors
keywords: Preventive medicine; exercise; physical fitness; smoking