title: Intense Walking Exercise Affects Serum IGF-1 and IGFBP3.
abstract: BACKGROUND
  Insulin-like growth factor (IGF-1) is associated with chronic diseases such as diabetes, cardiovascular disease, and hypertension, as well as muscle dysfunction. Previous studies of exercise interventions yield controversial results regarding plasma IGF-1, IGFBP3, and IGF-1/IGFBP3 ratio. In this study, we examined whether 100 km walking exercise affects serum levels of IGF-1 and IGFBP3 and IGF-1/IGFBP3 ratio. We also investigated several metabolic-related blood parameters before and after walking.
  
  
  METHODS
  Participants were 14 healthy middle aged men (41.0 ± 6.78 years of age). We assessed body composition and measured metabolic-related blood indicators, such as such as lipid profiles, glucose, renal and hepatic metabolic bio-markers before and after a 100 km walking race. Blood samples from all participants were taken before and immediately after the walkathon. We also analyzed serum levels of IGF-1 and IGFBP3, and calculated the IGF-1/IGFBP3 ratio.
  
  
  RESULTS
  After participants completed a 100 km walking race, some of their metabolic profiles were markedly changed. Serum levels of IGF-1 and IGFBP3 were significantly decreased, and therefore the IGF-1/IGFBP3 ratio also decreased before and after 100 km of walking.
  
  
  CONCLUSIONS
  Our results indicate that intense walking exercise affects serum levels of IGF-1 and IGFBP3 as well as metabolic bio-markers including high density cholesterol, glucose and triglycerides.
authors.affiliation: Department of Physiology and Center for Exercise Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: TaeHo
authors.initials: T
authors.lastname: Kim
authors.affiliation: Department of Physiology and Center for Exercise Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Jae Seung
authors.initials: JS
authors.lastname: Chang
authors.affiliation: Department of Physiology and Center for Exercise Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Hanul
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Anesthesiology and Pain Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Kwang Ho
authors.initials: KH
authors.lastname: Lee
authors.affiliation: Department of Physiology and Center for Exercise Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: In Deok
authors.initials: ID
authors.lastname: Kong
keywords: IGF-1; IGFBP3; Walkathon