title: Muscle strength but not functional capacity is associated with plasma interleukin-6 levels of community-dwelling elderly women.
abstract: The association of plasma interleukin-6 (IL-6) levels, muscle strength and functional capacity was investigated in a cross-sectional study of community-dwelling elderly women from Belo Horizonte, Brazil. Elderly people who present controlled chronic diseases with no negative impact on physical, psychosocial and mental functionality are considered to be community-dwelling. Psychological and social stress due to unsuccessfully aging can represent a risk for immune system disfunctions. IL-6 levels, isokinetic muscle strength of knee flexion/extension, and functional tests to determine time required to rise from a chair and gait velocity were measured in 57 participants (71.21 +/- 7.38 years). Serum levels of IL-6 were measured in duplicate and were performed within one single assay (mouse monoclonal antibody against IL-6; High-Sensitivity, Quantikine, R & D Systems, USA; intra-assay coefficient of variance = 6.9-7.4%; interassay coefficient of variance = 9.6-6.5%; sensitivity = 0.016-0.110 pg/mL; mean = 0.039 pg/mL). Muscle strength was assessed with the isokinetic dynamometer Biodex System 3 Pro. After the Shapiro-Wilk normality test was applied, correlations were investigated using Spearman and Kruskal-Wallis tests. Post hoc analysis was performed using the Dunn test. A significant negative correlation was observed between plasma IL-6 levels (1.95 +/- 1.77 pg/mL) and muscle strength for knee flexion (70.70 +/- 21.14%; r = -0.265; P = 0.047) and extension (271.84 +/- 67.85%; r = -0.315; P = 0.017). No significant correlation was observed between IL-6 levels and the functional tests (time to rise from a chair = 14.65 +/- 2.82 s and gait velocity = 0.95 +/- 0.14 m/s). These results suggest that IL-6 is associated with reduced muscle strength.
authors.affiliation: Departamento de Fisioterapia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil.
authors.forename: D M G
authors.initials: DM
authors.lastname: Oliveira
authors.forename: F M S
authors.initials: FM
authors.lastname: Narciso
authors.forename: M L A S
authors.initials: ML
authors.lastname: Santos
authors.forename: D S
authors.initials: DS
authors.lastname: Pereira
authors.forename: F M
authors.initials: FM
authors.lastname: Coelho
authors.forename: J M D
authors.initials: JM
authors.lastname: Dias
authors.forename: L S M
authors.initials: LS
authors.lastname: Pereira
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D001938:Brazil; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005080:Exercise Test; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D007537:Isometric Contraction / Q000502:physiology; D007719:Knee Joint / Q000502:physiology*; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology / Q000528:radiation effects*; D018482:Muscle, Skeletal / Q000502:physiology*; D011795:Surveys and Questionnaires
chemical_list: D015415:Biomarkers; D015850:Interleukin-6