title: Obesity increases risk of declining physical activity over time in women: a prospective cohort study.
abstract: OBJECTIVE
  Research indicates that risk of obesity increases as physical activity (PA) decreases; however, the reciprocal effect has been rarely studied. The present investigation was conducted to determine the contribution of obesity on objectively measured PA over 20 months.
  
  
  METHODS
  A prospective cohort design with 254 middle-aged women was employed. Body fat percentage (BF%) was measured using Bod Pod, and obesity was defined as BF% ≥32%. PA was assessed objectively using 7-day accelerometry at baseline and ∼20 months later at follow-up.
  
  
  RESULTS
  Of the 254 subjects, 124 were obese (49%) at baseline. Mean BF% was 32.1 ± 7.8 and average age was 41.7 ± 3.1 years. Mean weekly PA was 2.79 ± 0.85 million activity counts for all participants. Over the 20-month period, PA decreased significantly more in obese women (-8.1% ± 27.1%) than in nonobese women (0.3% ± 31.7%) after adjusting for confounders (F = 5.3, P = 0.022). Moderate plus vigorous PA levels also decreased more in obese women (-28.1 ± 73.6 min/week) than in nonobese women (-5.9 ± 66.8 min/week), after adjusting for covariates (F = 7.84; P = 0.0055).
  
  
  CONCLUSIONS
  It appears that obese women tend to reduce PA over time at a faster rate than nonobese women. Evidently, obesity is a risk factor for decreasing PA over time in middle-aged women.
authors.affiliation: Healthy Weight Center, Helen DeVos Children's Hospital, MI, USA.
authors.forename: Jared M
authors.initials: JM
authors.lastname: Tucker
authors.forename: Larry A
authors.initials: LA
authors.lastname: Tucker
authors.forename: James
authors.initials: J
authors.lastname: Lecheminant
authors.forename: Bruce
authors.initials: B
authors.lastname: Bailey
mesh_terms: D061725:Accelerometry; D000273:Adipose Tissue / Q000378:metabolism; D000328:Adult; D015992:Body Mass Index; D016208:Databases, Factual; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D009043:Motor Activity; D009765:Obesity / Q000503:physiopathology*; D011446:Prospective Studies; D012307:Risk Factors; D012621:Seasons