title: Time spent walking or exercising and blood levels of insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 (IGFBP-3): A large-scale cross-sectional study in the Japan Collaborative Cohort study.
abstract: The preventive effects of physical activity against cancer may partly be ascribable to a possible decrease in insulin-like growth factor-I (IGF-I) induced by the activity. To examine the association of physical activity with IGF-I and IGF-binding protein-3 (IGFBP-3), we analyzed the data for control participants in a case-control study nested in the Japan Collaborative Cohort Study. A total of 3,598 men and 3,359 women throughout Japan, aged 40 to 79 years, were administered a lifestyle questionnaire and provided serum samples. The age- and body mass index (BMI)- adjusted serum levels of IGF-I and IGFBP-3 were lower among those who walked for longer times with a significant trend in both sexes (trend P < 0.01). Among participants who walked one hour or more per day, the mean levels of serum IGF-I and IGFBP-3 were 138.7 ng/ml and 2.87 microg/ml in men and 125.7 ng/ml and 3.14 microg/ml in women, respectively. The corresponding figures among those rarely walked were 147.4 ng/ml and 2.99 microg/ml in men and 132.3 ng/ml and 3.21 microg/ml in women. For IGF-I, adjustment for serum IGFBP-3 did not essentially alter such associations although the trend in women did not reach statistical significance. A decreased level of serum IGF-I was associated with longer exercise time in men even after adjustment for serum IGFBP-3 (trend P = 0.033 after adjustment for age, BMI, and serum IGFBP-3), whereas the time was positively correlated with serum IGF-I in women (trend P = 0.048). Our findings may partly explain the protective effects of physical activity against several sites of cancer.
authors.affiliation: Department of Preventive Medicine, Biostatistics and Medical Decision Making, Nagoya University Graduate School of Medicine, Japan. wakai@med.nagoya-u.ac.jp
authors.forename: Kenji
authors.initials: K
authors.lastname: Wakai
authors.forename: Koji
authors.initials: K
authors.lastname: Suzuki
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Ito
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Inaba
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tajima
authors.forename: Kei
authors.initials: K
authors.lastname: Nakachi
authors.forename: Akiko
authors.initials: A
authors.lastname: Tamakoshi
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D016022:Case-Control Studies; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007564:Japan; D008019:Life Style; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012307:Risk Factors; D016138:Walking / Q000502:physiology*
chemical_list: D015415:Biomarkers; D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I