title: Cardiorespiratory fitness as a quantitative predictor of all-cause mortality and cardiovascular events in healthy men and women: a meta-analysis.
abstract: BACKGROUND
  Epidemiological studies have indicated an inverse association between cardiorespiratory fitness (CRF) and coronary heart disease (CHD) or all-cause mortality in healthy participants.
  
  
  OBJECTIVE
  To define quantitative relationships between CRF and CHD events, cardiovascular disease (CVD) events, or all-cause mortality in healthy men and women.
  
  
  METHODS
  A systematic literature search was conducted for observational cohort studies using MEDLINE (1966 to December 31, 2008) and EMBASE (1980 to December 31, 2008). The Medical Subject Headings search terms used included exercise tolerance, exercise test, exercise/physiology, physical fitness, oxygen consumption, cardiovascular diseases, myocardial ischemia, mortality, mortalities, death, fatality, fatal, incidence, or morbidity. Studies reporting associations of baseline CRF with CHD events, CVD events, or all-cause mortality in healthy participants were included.
  
  
  METHODS
  Two authors independently extracted relevant data. CRF was estimated as maximal aerobic capacity (MAC) expressed in metabolic equivalent (MET) units. Participants were categorized as low CRF (< 7.9 METs), intermediate CRF (7.9-10.8 METs), or high CRF (> or = 10.9 METs). CHD and CVD were combined into 1 outcome (CHD/CVD). Risk ratios (RRs) for a 1-MET higher level of MAC and for participants with lower vs higher CRF were calculated with a random-effects model.
  
  
  RESULTS
  Data were obtained from 33 eligible studies (all-cause mortality, 102 980 participants and 6910 cases; CHD/CVD, 84 323 participants and 4485 cases). Pooled RRs of all-cause mortality and CHD/CVD events per 1-MET higher level of MAC (corresponding to 1-km/h higher running/jogging speed) were 0.87 (95% confidence interval [CI], 0.84-0.90) and 0.85 (95% CI, 0.82-0.88), respectively. Compared with participants with high CRF, those with low CRF had an RR for all-cause mortality of 1.70 (95% CI, 1.51-1.92; P < .001) and for CHD/CVD events of 1.56 (95% CI, 1.39-1.75; P < .001), adjusting for heterogeneity of study design. Compared with participants with intermediate CRF, those with low CRF had an RR for all-cause mortality of 1.40 (95% CI, 1.32-1.48; P < .001) and for CHD/CVD events of 1.47 (95% CI, 1.35-1.61; P < .001), adjusting for heterogeneity of study design.
  
  
  CONCLUSIONS
  Better CRF was associated with lower risk of all-cause mortality and CHD/CVD. Participants with a MAC of 7.9 METs or more had substantially lower rates of all-cause mortality and CHD/CVD events compared with those with a MAC of less 7.9 METs.
authors.affiliation: Department of Internal Medicine, University of Tsukuba Institute of Clinical Medicine, 3-2-7 Miya-machi, Mito, Ibaraki 310-0015, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Kodama
authors.forename: Kazumi
authors.initials: K
authors.lastname: Saito
authors.forename: Shiro
authors.initials: S
authors.lastname: Tanaka
authors.forename: Miho
authors.initials: M
authors.lastname: Maki
authors.forename: Yoko
authors.initials: Y
authors.lastname: Yachi
authors.forename: Mihoko
authors.initials: M
authors.lastname: Asumi
authors.forename: Ayumi
authors.initials: A
authors.lastname: Sugawara
authors.forename: Kumiko
authors.initials: K
authors.lastname: Totsuka
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Shimano
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Ohashi
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Yamada
authors.forename: Hirohito
authors.initials: H
authors.lastname: Sone
mesh_terms: D002318:Cardiovascular Diseases / Q000453:epidemiology*; D003327:Coronary Disease / Q000453:epidemiology; D017079:Exercise Tolerance; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D009026:Mortality; D010101:Oxygen Consumption; D010809:Physical Fitness