title: Associations of objectively-assessed physical activity and sedentary time with depression: NHANES (2005-2006).
abstract: BACKGROUND
  Studies provide conflicting evidence for the protective effects of moderate-to-vigorous-intensity physical activity on depression. Recent evidence suggests that sedentary behaviors may also be associated with depression.
  
  
  OBJECTIVE
  To examine the associations of accelerometer-derived moderate-to-vigorous-intensity physical activity and sedentary time with depression among a population-based sample.
  
  
  METHODS
  Cross-sectional study using 2,862 adults from the 2005-2006 US National Health and Nutrition Examination Survey. ActiGraph accelerometers were used to derive both moderate-to-vigorous-intensity physical activity and sedentary time.
  
  
  RESULTS
  Depression occurred in 6.8% of the sample. For moderate-to-vigorous-intensity physical activity, compared with those in quartile 1 (least active), significantly lower odds of depression were observed for those participants in quartiles 2 (OR=0.55, 95% CI, 0.34 to 0.89), 3 (OR=0.49, 95% CI, 0.26 to 0.93), and 4 (most active) (OR=0.37, 95% CI, 0.20 to 0.70) (p for trend p<0.01). In overweight/obese participants only, those in quartile 4 (most sedentary) had significantly higher odds for depression than those in quartile 1 (least sedentary) [quartile 3 vs 1 (OR=1.94, 95% CI, 1.01 to 3.68) and 4 vs 1 (OR=3.09, 95% CI, 1.25 to 7.68)].
  
  
  CONCLUSIONS
  The current study identified lower odds of depression were associated with increasing moderate-to-vigorous-intensity physical activity and decreasing sedentary time, at least within overweight/obese adults.
authors.affiliation: Athabasca University, Athabasca, AB, Canada. jeffv@athabascau.ca
authors.forename: Jeff K
authors.initials: JK
authors.lastname: Vallance
authors.forename: Elisabeth A H
authors.initials: EA
authors.lastname: Winkler
authors.forename: Paul A
authors.initials: PA
authors.lastname: Gardiner
authors.forename: Genevieve N
authors.initials: GN
authors.lastname: Healy
authors.forename: Brigid M
authors.initials: BM
authors.lastname: Lynch
authors.forename: Neville
authors.initials: N
authors.lastname: Owen
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D003866:Depressive Disorder / Q000503:physiopathology* / Q000523:psychology; D015444:Exercise / Q000502:physiology* / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D009765:Obesity / Q000503:physiopathology / Q000523:psychology; D050177:Overweight / Q000503:physiopathology / Q000523:psychology; D057185:Sedentary Behavior; D011795:Surveys and Questionnaires