title: Association of IGF-I levels with muscle strength and mobility in older women.
abstract: The functional consequences of the age-associated decline in IGF-I are unknown. We hypothesized that low IGF-I levels in older women would be associated with poor muscle strength and mobility. We assessed this question in a population representative of the full spectrum of health in the community, obtaining serum IGF-I levels from women aged 70-79 yr, enrolled in the Women's Health and Aging Study I or II. Cross-sectional analyses were performed using 617 women with IGF-I levels drawn within 90 d of measurement of outcomes. After adjustment for age, there was an association between IGF-I and knee extensor strength (P = 0.004), but not anthropometry or other strength measures. We found a positive relationship between IGF-I levels and walking speed for IGF-I levels below 50 microg/liter (P < 0.001), but no relationship above this threshold. A decline in IGF-I level was associated with self-reported difficulty in mobility tasks. All findings were attenuated after multivariate adjustment. In summary, in a study population including frail and healthy older women, low IGF-I levels were associated with poor knee extensor muscle strength, slow walking speed, and self-reported difficulty with mobility tasks. These findings suggest a role for IGF-I in disability as well as a potential target population for interventions to raise IGF-I levels.
authors.affiliation: Department of Medicine, The Johns Hopkins Medical Institution, Baltimore, Maryland 21205, USA. acappola@medicine.umaryland.edu
authors.forename: A R
authors.initials: AR
authors.lastname: Cappola
authors.forename: K
authors.initials: K
authors.lastname: Bandeen-Roche
authors.forename: G S
authors.initials: GS
authors.lastname: Wand
authors.forename: S
authors.initials: S
authors.lastname: Volpato
authors.forename: L P
authors.initials: LP
authors.lastname: Fried
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000375:Aging / Q000502:physiology; D001823:Body Composition / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D003430:Cross-Sectional Studies; D005260:Female; D018737:Hand Strength / Q000502:physiology; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000502:physiology*; D018962:Phlebotomy; D011597:Psychomotor Performance / Q000502:physiology
chemical_list: D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I