title: Depression Symptom Severity and Cardiorespiratory Fitness in Healthy and Depressed Adults: A Systematic Review and Meta-Analysis.
abstract: BACKGROUND
  Depression symptom severity and cardiorespiratory fitness (CRF) are significant predictors of mortality and disability. However, the relationship between the two is unclear.
  
  
  OBJECTIVE
  This meta-analysis assessed the relationship between depression symptom severity and CRF in healthy and depressed adults (aged 18 years and over).
  
  
  METHODS
  The PubMed, Cochrane Library, Google Scholar and ProQuest databases were browsed for relevant English-language studies published from January 2000 to August 2014.
  
  
  METHODS
  Studies reporting a correlation between a depression scale and maximum oxygen consumption (VO2peak), as well as studies from the data of which such a correlation could be calculated, were included in this analysis.
  
  
  METHODS
  Correlation coefficients (CCs) were converted to Fisher's z values, and the analysis was performed using a random-effects model. Then, summary effects and 95% confidence intervals (CIs) were converted back to CCs.
  
  
  RESULTS
  Sixteen studies (totalling 4039 participants) were included in this analysis. A modest correlation between depression symptom severity and CRF was found (CC -0.16, 95% CI -0.21 to -0.10), appearing stronger in male participants (CC - 0.22, 95% CI -0.26 to -0.18) than in female participants (CC -0.12, 95% CI -0.19 to -0.05; p = 0.01). There was no difference in the summary effect between healthy and depressed adults (p = 0.43). Heterogeneity was moderate (I2 = 33%; p = 0.09).
  
  
  CONCLUSIONS
  Depression symptom severity is inversely correlated with CRF, and this correlation is stronger in men than in women. Clinical and prognostic implications of the correlation are discussed. These findings should stimulate further research on the effects of treating one variable on the other.
authors.affiliation: Cardiac Rehabilitation Department, Heart Hospital, Hamad Medical Corporation, Doha, Qatar. tpapasavvas@hamad.qa.|School of Biological Sciences, University of Essex, Colchester, UK. tpapasavvas@hamad.qa.
authors.forename: Theodoros
authors.initials: T
authors.lastname: Papasavvas
authors.affiliation: Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: Robert O
authors.initials: RO
authors.lastname: Bonow
authors.affiliation: Cardiac Rehabilitation Department, Heart Hospital, Hamad Medical Corporation, Doha, Qatar.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Alhashemi
authors.affiliation: School of Biological Sciences, University of Essex, Colchester, UK.
authors.forename: Dominic
authors.initials: D
authors.lastname: Micklewright
mesh_terms: D000328:Adult; D000072599:Cardiorespiratory Fitness; D003863:Depression / Q000175:diagnosis*; D003865:Major Depressive Disorder / Q000175:diagnosis; D005260:Female; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D017594:Publication Bias