title: Association of circulating IGF-I and IGFBP-3 concentrations and exercise capacity in healthy volunteers: results of the Study of Health in Pomerania.
abstract: BACKGROUND
  Insulin-like growth factor I (IGF-I) and its binding protein 3 (IGFBP-3) are central mediators of endocrine effects of growth hormone and there is increasing evidence for an association with muscle strength and exercise capacity. The aim of the present study was to clarify the possible association of circulating IGF-I and IGFBP-3 concentrations and exercise capacity in a general adult population.
  
  
  METHODS
  From the Study of Health in Pomerania (SHIP) 1332 subjects aged 25 to 85 years participated in a standardised symptom limited cardiopulmonary exercise test on a bicycle. Exercise capacity was characterized by oxygen uptake at anaerobic threshold (VO₂@AT), peak exercise (peakVO₂), oxygen pulse and maximum power output at peak exertion. Multivariable linear regression analyses adjusted for age, sex, body mass index, physical activity and smoking were performed.
  
  
  RESULTS
  At peak exercise performance, in women IGF-I showed significant associations to peakVO₂ and maximum power output, IGF-I/IGFBP-3 ratio was associated with maximum power output. In men, this association was not consistently reproducible. Neither IGF-I nor IGFBP-3 did reveal any association to VO₂@AT in both genders.
  
  
  CONCLUSIONS
  Serum IGF-I concentrations are associated with peak exercise capacity in healthy women, but not in men over a wide range in ages, body sizes and activity scores.
authors.affiliation: Department of Internal Medicine B - Cardiology, Intensive Care, Pulmonary Medicine and Infectious Diseases, University Hospital Ferdinand-Sauerbruchstrasse, D-17475 Greifswald, Germany. glaeser.sven@gmail.com
authors.forename: Sven
authors.initials: S
authors.lastname: Gläser
authors.forename: Nele
authors.initials: N
authors.lastname: Friedrich
authors.forename: Ralf
authors.initials: R
authors.lastname: Ewert
authors.forename: Christoph
authors.initials: C
authors.lastname: Schäper
authors.forename: Alexander
authors.initials: A
authors.lastname: Krebs
authors.forename: Marcus
authors.initials: M
authors.lastname: Dörr
authors.forename: Henry
authors.initials: H
authors.lastname: Völzke
authors.forename: Stephan B
authors.initials: SB
authors.lastname: Felix
authors.forename: Matthias
authors.initials: M
authors.lastname: Nauck
authors.forename: Henri
authors.initials: H
authors.lastname: Wallaschofski
authors.forename: Beate
authors.initials: B
authors.lastname: Koch
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D054874:Athletic Performance / Q000502:physiology; D015444:Exercise / Q000502:physiology; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D005858:Germany; D006262:Health; D064368:Healthy Volunteers; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood* / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000032:analysis* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D012129:Respiratory Function Tests
chemical_list: D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I