title: Circulating pro-inflammatory cytokines are elevated and peak power output correlates with 25-hydroxyvitamin D in vitamin D insufficient adults.
abstract: The purpose of this study was to identify circulating cytokines, skeletal muscle strength, and peak power output in young adults with contrasting serum 25-hydroxyvitamin D (25(OH)D) concentrations. Serum 25(OH)D, inflammatory cytokines, muscle strength, and peak power output were, therefore, measured in young adults (25-42 years). Data were collected during the winter to avoid the seasonal influence on serum 25(OH)D. After serum 25(OH)D concentration measurements, subjects were separated into one of two groups: (1) vitamin D insufficient [serum 25(OH)D ≤32 ng/mL, n = 14], or (2) vitamin D sufficient [serum 25(OH)D >32 ng/mL, n = 14]. Following group allocation, serum 25(OH)D concentrations were significantly (p < 0.05) lower and pro-inflammatory cytokines [interleukin (IL)-2, IL-1β, tumor necrosis factor-α, and interferon-γ] were significantly (all p < 0.05) greater in vitamin D insufficient adults. An anti-inflammatory cytokine (i.e., IL-10; p > 0.05), peak isometric forces (p > 0.05), and peak power outputs (p > 0.05) were not significantly different between vitamin D groups. However, peak power outputs correlated with serum 25(OH)D concentrations in vitamin D insufficient (r = 0.55, p < 0.05) but not in vitamin D sufficient adults (r = -0.27, p = 0.36). Based on these data, we conclude that vitamin D insufficiency, in part, could result in pro-inflammatory stress without altering muscular strength or function in young adults. Future research investigating the causality of the correlation between low-serum 25(OH)D and peak power output in young adults is required.
authors.affiliation: The Orthopedic Specialty Hospital, 5848 S. Fashion Blvd, Murray, UT 84107, USA. tyler.barker@imail.org
authors.forename: Tyler
authors.initials: T
authors.lastname: Barker
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Martins
authors.forename: Harry R
authors.initials: HR
authors.lastname: Hill
authors.forename: Carl R
authors.initials: CR
authors.lastname: Kjeldsberg
authors.forename: Brian M
authors.initials: BM
authors.lastname: Dixon
authors.forename: Erik D
authors.initials: ED
authors.lastname: Schneider
authors.forename: Vanessa T
authors.initials: VT
authors.lastname: Henriksen
authors.forename: Lindell K
authors.initials: LK
authors.lastname: Weaver
mesh_terms: D000328:Adult; D016207:Cytokines / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000503:physiopathology*
chemical_list: D016207:Cytokines; D014807:Vitamin D; C104450:25-hydroxyvitamin D