title: Bicycling but not walking is independently associated with fasting insulin in abdominally obese women.
abstract: BACKGROUND
  The impact of walking and bicycling on insulin resistance (IR) in women with abdominal obesity is unclear.
  
  
  METHODS
  Pooled analysis of data from a randomized trial on physically active commuting (bicycling + walking vs walking only) in women with abdominal obesity [n = 98; age:47.3 ± 7.6 yrs; waist circumference (WC):103.1 ± 7.8 cm]. Bicycling and walking data were collected during 7 consecutive days by trip meters (Trelock FC-410) and pedometers (Yamax digiwalker SW-200) at baseline, 2, 4, and 6 months. Owing to a skew distribution we analyzed bicycling as a binary dummy variable with a 10 km/week cut-off. Fasting serum insulin and homeostatic model assessment - insulin resistance (HOMA-IR) were assessed at baseline and 6 months, as were body mass index (BMI), WC, and dual x-ray absorptiometry (DXA)-assessed % whole-body fat.
  
  
  RESULTS
  Increased bicycling by 10 km/wk was associated with reductions in fasting serum insulin at follow-up independent of age, treatment allocation, baseline phenotype, Δ walking, and Δ % body fat (β = -10.9, P = .042), but not HOMA-IR (β = -2.0, P = .13). Increased walking was not associated with fasting serum insulin (P = .33) or HOMA-IR (P = .44) at follow-up, after adjustment for the same covariates and Δ bicycling.
  
  
  CONCLUSIONS
  Increased bicycling but not walking was associated with reduced insulin levels at follow-up. Bicycling may be more effective than walking for reducing insulin levels in abdominally obese women.
authors.affiliation: Dept of Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Hemmingsson
authors.forename: Ulf
authors.initials: U
authors.lastname: Ekelund
authors.forename: Joanna
authors.initials: J
authors.lastname: Udden
mesh_terms: D000328:Adult; D001642:Bicycling; D005215:Fasting; D005260:Female; D006293:Health Promotion; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D008875:Middle Aged; D009765:Obesity; D016138:Walking
chemical_list: D007328:Insulin