title: Insulin-sensitizing effects of exercise on adiponectin and retinol-binding protein-4 concentrations in young and middle-aged women.
abstract: BACKGROUND
  Exercise training enhances insulin sensitivity. Changes in retinol-binding protein-4 (RBP4) and adiponectin levels are linked to insulin resistance.
  
  
  OBJECTIVE
  We tested whether the insulin-sensitizing effect of exercise is associated with age-related changes in circulating RBP4 and adiponectin levels in women.
  
  
  METHODS
  We studied 36 healthy young (22.4 +/- 2.8 yr) and 38 middle-aged (59.8 +/- 5.9 yr) women. All subjects performed 60 min of aerobic exercise three times per week for 10 wk at about 70% maximal exercise capacity.
  
  
  RESULTS
  After a 10-wk training program, maximal exercise capacity was significantly increased in both young and middle-aged women, suggesting increased oxidative capacity. Insulin sensitivity was also improved, as indicated by decreases in plasma insulin levels and homeostasis model assessment for insulin resistance index. Serum adiponectin and RBP4 concentrations were increased and decreased more in older than younger women, respectively (P < 0.01). Concurrently, circulating transthyretin levels were also decreased in older subjects in response to exercise training. The older women showed higher correlations between changes in adiponectin or RBP4 levels and obesity indices or metabolic parameters than the younger group. When subjects showing increasing adiponectin or decreasing RBP4 levels were classified as responders, there were higher correlations between these changes in responders than in nonresponders.
  
  
  CONCLUSIONS
  We conclude that the mechanism for the insulin-sensitizing effects of exercise could involve increased adiponectin and reduced RBP4 levels in exercise-trained women. These data suggest that alterations in circulating RBP4 and adiponectin levels could play an important role in regulating insulin sensitivity.
authors.affiliation: Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 28 Yongon-dong Chongno-gu, Seoul, Korea.
authors.forename: Soo
authors.initials: S
authors.lastname: Lim
authors.forename: Sung Hee
authors.initials: SH
authors.lastname: Choi
authors.forename: In-Kyong
authors.initials: IK
authors.lastname: Jeong
authors.forename: Jae Hyeon
authors.initials: JH
authors.lastname: Kim
authors.forename: Min Kyong
authors.initials: MK
authors.lastname: Moon
authors.forename: Kyong Soo
authors.initials: KS
authors.lastname: Park
authors.forename: Hong Kyu
authors.initials: HK
authors.lastname: Lee
authors.forename: Young-Bum
authors.initials: YB
authors.lastname: Kim
authors.forename: Hak Chul
authors.initials: HC
authors.lastname: Jang
mesh_terms: D052242:Adiponectin / Q000097:blood* / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D008875:Middle Aged; D011228:Prealbumin / Q000032:analysis; D054839:Retinol-Binding Proteins, Plasma / Q000032:analysis* / Q000378:metabolism
chemical_list: D052242:Adiponectin; D011228:Prealbumin; C101326:RBP4 protein, human; D054839:Retinol-Binding Proteins, Plasma